Choosing the right marine coating can be confusing. Polyurethane, gelcoat, and epoxy each serve different purposes, and selecting the wrong system can lead to peeling, chalking, poor adhesion, or early failure. This guide clearly explains the strengths and weaknesses of each coating so you can choose the best option for your boat project.
If you’re still exploring paint systems in general, see our Marine Paint & Coatings Overview for primers, topside paint, antifouling, and specialty finishes.
What Is Polyurethane?
Marine polyurethane topside paint is a high-gloss, durable finish ideal for above-waterline surfaces. It offers outstanding UV resistance, long-term gloss retention, and a professional yacht-grade appearance.
Highly flexible and weather resistant
Exceptional color and gloss retention
Easy to clean and maintain
Best for: topsides, decks, trim, masts, metalwork, and refinishing aged gelcoat.
Epoxy primers and epoxy barrier coats are extremely strong and adhesive coatings used as a base layer or waterproofing system. They bond exceptionally well to fiberglass, metal, and wood.
Superior adhesion and structural strength
Excellent waterproofing for blister prevention
Ideal as a base for polyurethane or antifouling coatings
Best for: fiberglass repairs, underwater protection, and hull barrier coat systems.
What Is Gelcoat?
Gelcoat is the high-build coating used in fiberglass boat construction. It creates a thick, durable surface when applied in a mold or during repairs.
High build and sandable
Buffs to a glossy shine
Less UV stable unless regularly maintained
Best for: new fiberglass work, mold repairs, and OEM-style finishes.
You are protecting the hull with a moisture barrier
When to Choose Gelcoat
You are restoring or repairing molded fiberglass
You want an OEM-thick finish
You prefer a sandable and buffable finish
Which Coating Lasts Longest?
Epoxy – best structural durability and waterproofing (must be topcoated)
Polyurethane – best UV and weathering performance above the waterline
Gelcoat – durable but prone to oxidation and chalking over time
FAQs
Can polyurethane go over gelcoat?
Yes. Sand the gelcoat to a uniform, dull finish, repair defects, and apply a compatible primer before polyurethane. Proper surface prep is essential for adhesion.
Is epoxy waterproof?
Yes. Epoxy forms an excellent moisture barrier and is commonly used as a hull barrier coat beneath antifouling or polyurethane paint.
Should I use gelcoat to refinish an old boat?
For full topside restoration, polyurethane paint is typically easier and offers better long-term UV resistance than rebuilding with gelcoat.
Can I use polyurethane below the waterline?
No. Polyurethane is not recommended for constant immersion. Use an epoxy barrier coat and a compatible antifouling paint instead.
Check the catalyst ratio immediately: Incomplete or incorrect MEKP mixing is the most common cause of uncured gelcoat.
Confirm curing conditions: Gelcoat requires proper temperature, humidity control, and oxygen exclusion to fully cure.
Do not apply more gelcoat yet: Uncured material must be removed or sealed correctly before recoating.
Bottom line: Gelcoat that doesn’t cure is usually a process issue—not a product failure—and can often be corrected with the right next steps.
Tip: Gelcoat exposed to air will remain tacky unless a wax additive or PVA is used on the final coat.
Quick Answer: Why Did My Gelcoat Not Cure?
Gelcoat usually does not cure because the catalyst ratio was incorrect, the MEKP catalyst was not mixed thoroughly, the temperature was too cold, the gelcoat was applied too thick or too thin, or the surface was contaminated with wax, solvent, moisture, oil, or residue. In some cases, the gelcoat may also stay tacky because it was unwaxed gelcoat exposed to air.
If your gelcoat is still soft, gummy, sticky, or wet after the expected cure time, do not sand it aggressively right away. First, determine whether the problem is surface tackiness, slow curing, incorrect catalyst mixing, or a failed cure. The right fix depends on how uncured the gelcoat is and what caused the problem.
Gelcoat Not Curing: Most Common Causes and Fixes
Problem
Likely Cause
What to Do Next
Gelcoat is sticky on the surface but firm underneath
Unwaxed gelcoat exposed to air
Apply PVA, wax additive, or another sealing method recommended for the product so the surface can fully cure.
Gelcoat is soft or gummy throughout
Too little MEKP catalyst or poor mixing
Allow more time if conditions are cool, but if it remains soft, the uncured material may need to be removed and reapplied.
Gelcoat cures unevenly
Catalyst was not mixed thoroughly
Remove uncured or weak areas, sand the surface once stable, and reapply properly mixed gelcoat.
Gelcoat takes much longer than expected to cure
Low temperature, high humidity, or low catalyst amount
Move the project into a warmer, controlled area if possible and allow additional cure time before deciding it has failed.
Gelcoat wrinkles, cracks, or overheats
Too much catalyst or gelcoat applied too thick
Let it fully cure if possible, then sand or grind out damaged areas and reapply in proper thickness.
Gelcoat will not bond properly
Surface contamination or poor sanding
Remove the failed coating, clean thoroughly, sand properly, and reapply to a clean, dry surface.
Gelcoat remains wet and never hardens
No catalyst, expired catalyst, wrong product mix, or severe measurement error
Remove the uncured gelcoat completely, clean the area, and start over with fresh materials.
What to Check Before You Remove the Gelcoat
Before removing uncured gelcoat, check the product instructions, catalyst ratio, working temperature, cure time, and whether the gelcoat was waxed or unwaxed. A surface that is slightly tacky may not be a failed cure if unwaxed gelcoat was used without PVA or wax additive.
If the gelcoat is soft all the way through, transfers onto your glove, or can be scraped off easily after the normal cure window, the cure may have failed. In that case, it is usually better to remove the uncured material than to try to cover it with more gelcoat, primer, or paint.
Basic Steps to Fix Gelcoat That Did Not Cure
Step
What to Do
Why It Matters
1. Identify the type of uncured gelcoat
Check whether the surface is only tacky or whether the gelcoat is soft throughout.
Surface tackiness and total cure failure require different fixes.
2. Check the gelcoat type
Confirm whether you used waxed gelcoat, unwaxed gelcoat, or gelcoat with a separate surfacing agent.
Unwaxed gelcoat often needs air exclusion to cure tack-free.
3. Review the catalyst ratio
Compare the MEKP amount used with the manufacturer’s recommended ratio.
Too little catalyst can prevent curing, while too much can cause cracking, overheating, or poor performance.
4. Consider temperature and cure time
Check whether the surface, air, and materials were warm enough during application and curing.
Cold conditions can slow or interfere with the curing process.
5. Remove failed material if needed
Scrape, wipe, or sand away uncured gelcoat depending on how soft it is.
New gelcoat should not be applied over a soft, unstable, or contaminated layer.
6. Clean and prepare the surface again
Remove residue, solvent, wax, oil, moisture, and dust before recoating.
Proper surface prep helps the new gelcoat bond and cure correctly.
7. Reapply with fresh gelcoat and catalyst
Measure carefully, mix thoroughly, and follow product directions for thickness, temperature, and cure time.
Accurate mixing and application reduce the chance of another failed cure.
Common Questions About Gelcoat That Did Not Cure
Will uncured gelcoat eventually harden?
Sometimes gelcoat will eventually harden if the problem is cool temperature or slightly slow curing. However, if the gelcoat has too little catalyst, no catalyst, poor mixing, contamination, or expired materials, it may never cure properly and may need to be removed.
Why is my gelcoat still tacky?
Gelcoat may stay tacky if it is unwaxed gelcoat and the surface was exposed to air while curing. It can also remain tacky because of incorrect catalyst ratio, poor mixing, cold temperatures, or contamination. The key is determining whether only the surface is tacky or the entire layer is soft.
Can I apply more gelcoat over uncured gelcoat?
In most cases, you should not apply fresh gelcoat over soft or uncured gelcoat. The new layer may not bond correctly, and the failed layer underneath can continue to cause problems. It is usually better to remove uncured material, clean the area, sand properly, and reapply.
How do I remove gelcoat that did not cure?
Soft or gummy gelcoat can often be scraped off carefully before final cleaning. Remaining residue may need to be removed with the cleaner or solvent recommended by the product manufacturer, followed by sanding and surface preparation before recoating.
What happens if I use too much MEKP catalyst?
Too much MEKP catalyst can cause gelcoat to cure too quickly, overheat, crack, discolor, shrink, or become brittle. More catalyst is not always better. Always follow the gelcoat manufacturer’s recommended catalyst range for the temperature and application conditions.
What happens if I do not use enough catalyst?
Too little catalyst can cause gelcoat to cure slowly, remain soft, or fail to cure completely. If the gelcoat remains gummy or wet after the expected cure time, the uncured material may need to be removed and reapplied with the correct catalyst ratio.
Does temperature affect gelcoat curing?
Yes, temperature can strongly affect gelcoat curing. Cold surfaces, cold air, and cold materials can slow down or interfere with the cure. Gelcoat products usually have a recommended temperature range, and staying within that range helps the coating cure properly.
Do I need wax additive in gelcoat?
Wax additive is often used when gelcoat is intended as a final coat. It rises to the surface and helps block air so the gelcoat can cure tack-free. If you are using unwaxed gelcoat, you may need wax additive, PVA, or another manufacturer-approved air-blocking method.
Can I sand gelcoat that is still tacky?
Gelcoat that is still sticky or gummy is difficult to sand and can clog sandpaper quickly. If the surface is only slightly tacky because it needs air exclusion, address that first. If the gelcoat is soft throughout, it may need to be removed before sanding and recoating.
Recommended Gelcoat Repair Supplies
Bottom Paint Store carries gelcoat repair products, MEKP catalyst, wax additive, PVA, fiberglass repair materials, sandpaper, cleaners, fillers, fairing compounds, and related marine finishing supplies. The right product depends on whether you are fixing surface tackiness, removing a failed cure, or reapplying gelcoat after a repair.
Gelcoat Not Curing? Causes, Fixes, and Prevention Tips
Applying gelcoat can feel intimidating, even for experienced do-it-yourselfers. Unlike paint, gelcoat involves a precise chemical reaction that requires careful measuring and preparation. When it stays tacky or won’t harden at all, it can be one of the most frustrating issues in fiberglass repair. Don’t worry—uncured gelcoat is a common problem with clear, fixable causes.
This guide explains the most common reasons why gelcoat fails to cure, how to fix it, and how to prevent it from happening again.
Common Reasons Gelcoat Does Not Cure
1. Incorrect Surface Preparation
Gelcoat adheres only to fiberglass, cured gelcoat, or polyester resin. It will not stick to paint, epoxy, or any protective coating. Always remove existing paint completely before applying new gelcoat.
Sanding: Use 40–80 grit sandpaper for heavy removal or shaping and 220–330 grit for feathering edges of the repair. A rubber sanding block helps maintain flat surfaces.
Cleaning: Wipe the surface with acetone to remove grease, wax, or dust. The surface must be completely clean and dry before applying gelcoat.
Recommended Tools: 3M abrasives and clean lint-free cloths provide the best bond.
Skipping or rushing surface prep is one of the most common reasons gelcoat remains tacky or peels later.
2. Incorrect Catalyst Ratio (MEKP)
Gelcoat requires a precise mix of MEKP catalyst to harden correctly. Most products need 1.5%–2.0% by volume, with 1.8% @ 77°F being ideal (about 12 drops per ounce of gelcoat).
Too little catalyst: The gelcoat won’t “kick,” leaving a sticky, soft surface.
Too much catalyst: The mixture can overheat and harden in the can or while applying.
Always mix small batches—no more than one pint at a time—and stir thoroughly.
Temperature (°F)
Recommended Catalyst %
Notes
60–65°F
2.0%
Cooler temps require more MEKP
70–80°F
1.8%
Ideal range for most applications
85–90°F
1.5%
Reduce catalyst in warm weather
Gelcoat Recoat Checklist
Confirm whether the gelcoat is waxed or unwaxed
Use fresh gelcoat and fresh MEKP catalyst
Measure catalyst carefully according to the product directions
Mix thoroughly, including the sides and bottom of the mixing container
Apply within the recommended temperature range
Make sure the surface is clean, dry, sanded, and free of wax or oil
Use PVA or wax additive when required for a tack-free final cure
Allow the full cure time before sanding, polishing, painting, or launching
Pro Tip: Keep gelcoat at room temperature before use. For the most consistent cure, pour the mixed gelcoat into a clean second container before brushing or spraying. This ensures no uncatalyzed material remains on the sides of the pot.
3. Missing Wax Additive (Surfacing Agent)
Oxygen in the air prevents gelcoat from curing tack-free. The final coat must include a wax additive sanding aid to seal out oxygen and allow full cure. Use 1 oz wax per quart of gelcoat. The first coat usually doesn’t need wax, but the last coat does.
All gelcoats from the Bottom Paint Store include both MEKP catalyst and wax additive, but extra additives are available if needed.
4. Too Thin of a Coat
Gelcoat must be applied thick enough to generate heat for the curing reaction. The proper wet film thickness is about 25 mils, resulting in a cured thickness of 18–22 mils.
Use a wet film thickness gauge to confirm coverage. Press the edge of the gauge into the gelcoat until it contacts the surface below. The highest numbered tooth with gelcoat on it and the next higher tooth without gelcoat indicate the wet film thickness.
Example: If the 15-mil tooth is coated and the 20-mil tooth is clean, the film thickness is between 15 and 20 mils—too thin for proper curing.
What to Do If Your Gelcoat Didn’t Cure
Can I Apply More Gelcoat Over It?
No. Adding new gelcoat over an uncured layer will not make the first coat cure. The underlying gelcoat must be removed and reapplied.
Will It Cure With More Time?
Sometimes. If the mixture or temperature was slightly off, it may cure after a few days. However, if it’s still soft or tacky after 72 hours, it needs to be removed.
How to Remove Uncured Gelcoat
Wipe the surface with acetone to soften the uncured gelcoat.
Use a plastic putty knife to scrape off the material carefully.
Re-sand the area and clean thoroughly before reapplying gelcoat with the correct catalyst ratio and wax additive.
How to Prevent Gelcoat Cure Problems
Store and mix gelcoat at room temperature (70–80°F).
Measure catalyst with graduated mixing cups for accuracy.
Use wax additive in your final coat to achieve a hard, sandable surface.
Apply multiple thin coats instead of one heavy coat.
No. Gelcoat will not adhere directly to epoxy. You must apply a compatible barrier coat or primer first.
Why Is My Gelcoat Sticky After 24 Hours?
It’s usually caused by too little catalyst or forgetting the wax additive in the final coat.
How Long Should Gelcoat Take to Cure?
At 77°F, most gelcoats will be tack-free in 2–4 hours and fully cured within 24 hours.
Pro Tip 1 mL = 1 cc If using wood mixing stick, place stick in resin before adding catalyst so the wood doesn’t absorb catalyst. Only catalyze slightly more than needed. Resin that cures still in the mixing pot is unusable.
Note the size and temperature variables.For Darker Colors – use 2% MEKp
Can I apply more gelcoat over uncured gelcoat? No. Applying more gelcoat will not help the first layer cure. Most likely it will need to be removed and reapplied.
What can I try to get the gelcoat to cure? Allow more time. If something wasn’t exactly right, the gelcoat may just take a few days to harden. If it’s not rock-solid in a few days, though, you may have to scrape it off and reapply it.
How can I remove the uncured gelcoat? Acetone on a rag can be used to break down the gelcoat. Use a plastic putty knife to scrape the uncured gelcoat away.
Maintaining a boat involves more than just keeping it clean and stocked with gear—it’s about protecting your investment from the harsh marine environment. Two of the most common materials used in boat repair and maintenance are gelcoat and epoxy resin. While both serve vital roles in fiberglass boat construction and restoration, they are not interchangeable.
In this guide, we’ll break down the differences between gelcoat and epoxy, explain when to use each, and help you make informed decisions that will keep your boat seaworthy and looking sharp.
Gelcoat is a pigmented polyester or vinyl ester resin used as the outer layer of most fiberglass boats. It provides a smooth, glossy finish and helps protect the underlying fiberglass laminate from UV rays, water, and minor abrasions.
Primary Purpose: Aesthetic finish and surface protection
Application: Typically applied in a mold during boat construction or used later for cosmetic repairs
Our products are formulated to provide superior resistance to UV rays and meet the stringent requirements of the boating industry.
What is Epoxy?
Epoxy resin is a two-part adhesive consisting of a resin and a hardener. When mixed, it forms a strong, durable material ideal for structural repairs and bonding various surfaces, including fiberglass, wood, and metal.
Application: Used in layups, laminating, filling, or as a base layer for barrier coats
Tuff Stuff is designed as a high-build two-part epoxy primer, making it ideal for barrier coats, especially below the waterline. It’s specifically engineered to prevent water absorption and osmotic blistering in fiberglass hulls—a core strength of marine-grade epoxies.
Gelcoat is your best choice when the goal is cosmetic restoration of your boat’s surface—particularly fiberglass. It’s ideal for:
Repairing surface scratches and chips in the existing gelcoat
Restoring faded or oxidized areas
Matching the boat’s original finish and color
Protecting from UV damage and surface wear
However, gelcoat does not bond well to epoxy or non-polyester surfaces unless properly prepped. Also, it’s not suitable for deep repairs or structural issues.
Matching original boat color (especially white, because, well… everything’s white)
Cosmetic touch-ups above and below the waterline
Tip: Always sand and clean the surface thoroughly before applying gelcoat. If applying over epoxy, ensure the epoxy is fully cured and properly sanded to create a mechanical bond.
When to Use Epoxy
Epoxy is the material of choice when strength, durability, and waterproofing are the priorities. It excels in situations like:
Repairing delaminated fiberglass
Fixing holes, cracks, or structural damage
Bonding dissimilar materials like wood to fiberglass or metal
Sealing bare fiberglass or wood to prevent water intrusion
Creating a barrier coat to prevent blistering (osmosis)
Epoxy is more chemically resistant than polyester resins and has superior adhesive qualities. However, it requires a UV-resistant topcoat, such as topside boat paint or gelcoat, to protect it from sunlight degradation.
Best Time to Use Epoxy:
Repairing structural damage like cracks, holes, or delamination
Sealing bare fiberglass to prevent water intrusion
Adhering materials (wood, metal, composite) with confidence
Yes, but with preparation. Since gelcoat does not naturally adhere well to epoxy, the epoxy must be fully cured, sanded with 80–120 grit, and cleaned thoroughly to allow for mechanical bonding. Some professionals recommend applying a tie-coat primer to improve adhesion.
Choosing the Right Product
Use Gelcoat when:
You’re doing surface-level cosmetic work on fiberglass and want a UV-resistant, glossy finish.
Use Epoxy when:
You’re repairing structural damage, bonding materials, or sealing surfaces below the waterline.
Final Thoughts
Whether you’re restoring your hull’s shine or reinforcing a damaged section, knowing when to use gelcoat vs epoxy ensures your boat stays safe, seaworthy, and beautiful. Each material serves a distinct purpose—gelcoat for finishing and appearance, epoxy for strength and structural integrity.
By understanding their properties and correct applications, you’ll be able to tackle any repair with confidence—and save time and money in the long run.
Ready to tackle your next boat project like a pro?
Stock up on top-rated gelcoat and epoxy products at Bottom Paint Store and cruise into your next DIY with confidence. Need help? We are only a phone call 888-505-2313 or live chat away.
We hear from our customers all the time that gelcoat is one of the trickiest substances to work with. This is due to its unique requirements for proper curing, surface preparation, and application. Most bad outcomes can be eliminated by having a thorough plan and following it before charging ahead. In this guide we will walk you through 10 steps to take to ensure you get a great result. Let’s go!
Thorough Surface Preparation
Any successful gelcoat application starts with cleaning and prepping the surface. Remove dirt, grease, salts, oils, and loose paint by washing the area with a strong boat cleaner or solvent. Once washed, rinse thoroughly and allow the surface to dry completely. Properly preparing the substrate ensures a strong bond between the gelcoat and the boat’s surface.
Sanding and Fairing
After cleaning, sand the surface thoroughly to provide a consistent and slightly rough texture that gelcoat can adhere to. For repairs or badly worn surfaces, you may need to fill low spots with a marine-grade filler or fairing compound. Use progressively finer grit papers—starting around 80-100 grit for heavy material removal and moving up to 220-320 grit for the final finish.
Choose High-Quality Materials
Not all gelcoat products are created equal. Invest in premium gelcoat, catalysts (typically MEKP), and thinners or additives recommended by your chosen gelcoat manufacturer. Look for established marine brands known for durability, UV stability, and ease of application.
For over 50 years Fiberglass Coatings has been an industry leader in resin and coatings.
Carefully Measure and Mix
Accurate measuring of catalyst is critical for proper curing. Follow the recommended mixing ratio from the gelcoat manufacturer—too little catalyst may lead to incomplete curing, while too much can cause the gelcoat to harden too quickly or become brittle. Mix slowly but thoroughly, ensuring the catalyst is fully incorporated without introducing excess air.
Control Application Conditions
Gelcoat application is sensitive to temperature and humidity:
Temperature: Aim for 60–80°F (15–27°C). Below 60°F, curing slows; above 80°F, gelcoat can cure too quickly.
Humidity: High humidity can affect curing and lead to surface issues. If possible, apply gelcoat in a controlled environment or choose a time of day with optimal conditions.
Proper Application Tools
Decide whether to apply with a spray gun or a brush/roller. For larger areas or new builds, a specialized spray gun designed for gelcoat can achieve a smoother finish. However, for smaller patches or tight spaces, high-quality brushes or rollers are perfectly effective. Be sure to use tools designed for resin-based coatings to reduce bristle shedding or roller fuzz. Bottom Paint Store only sells sprayable gelcoat.
Build in Layers
Applying gelcoat in multiple thin layers helps you avoid sags, runs, and air pockets. For spraying, use steady, even passes with a 50% overlap. If brushing or rolling, use smooth, consistent strokes, allowing each thin coat to cure to a tacky state before adding the next. This layering approach promotes a uniform finish and proper thickness.
Allow for Correct Cure Times
Each layer of gelcoat requires sufficient time to set before proceeding. If you apply the next layer too soon, you risk trapping solvents or causing an improper bond. Follow the manufacturer’s recommended recoat window. When in doubt, err on the side of slightly longer cure times, especially under cooler or more humid conditions.
Sand and Polish for Final Finish
After your last gelcoat layer has fully cured, lightly sand the surface with progressively finer grits (e.g., 400 → 600 → 800 → 1000, etc.). This process removes minor imperfections and levels the surface. Once the sanding scratches are gone, move on to polishing compounds to restore gloss and smoothness. Carefully buff the area, then clean away any polishing residue.
Seal and Protect
A final protective wax or sealant can help protect the gelcoat from UV damage and staining. Choose a high-quality marine wax or polymer sealant suitable for fiberglass boats. Reapply it regularly to maintain protection and keep your gelcoat surface looking fresh and glossy.
By following these 10 key steps—covering everything from surface prep and mixing ratios to proper application and finishing—you’ll be well on your way to a boat surface that looks professional and stands the test of time. Quality materials, attention to detail, and patience are the cornerstones of a successful gelcoat application.
When changing the color of your boat’s gelcoat, using pigment agents effectively is crucial to achieving the desired shade.
Here’s how you can use these agents to customize your boat’s appearance:
Choose the Right Pigment Agents: Select pigment agents that are specifically formulated for use with gelcoat. These pigments are designed to blend seamlessly and maintain the durability and UV resistance of the gelcoat. For a variety of pigment options and specific products, check out our Pigments For Gel Coats And Resins
Test Color Mixes:
Before applying the pigment to the entire boat, it’s wise to test the color mixture on a small scale. Mix a small amount of gelcoat with your chosen pigment according to the guidelines provided. This test will help you adjust the color intensity and ensure that it meets your expectations before full application.
Measure Precisely:
For consistent color throughout your gelcoat, measure the pigment and gelcoat precisely. Consider using a digital scale for accuracy, and follow the manufacturer’s recommendations for pigment-to-gelcoat ratios. Typically, a small amount of pigment goes a long way.
Mix Thoroughly:
To avoid any color inconsistencies, mix the pigment thoroughly with the gelcoat. Ensure that there are no streaks or clumps of pigment. A mechanical mixer can be very effective in achieving a homogeneous mixture.
Apply a Test Patch:
Apply a small amount of the colored gelcoat to a part of the boat that is less visible. Allow it to cure fully according to the gelcoat’s curing instructions. This will give you a real sense of how the color looks when applied and finished.
Adjust if Necessary:
If the test patch isn’t to your satisfaction, adjust the pigment ratio as needed. Adding more pigment will deepen the color, while adding more gelcoat will lighten it.
Apply to the Boat:
Once you are satisfied with the color mix, apply the pigmented gelcoat to the boat using your chosen application method (brush and roller or spraying). Ensure even coverage to avoid blotchy areas.
By carefully selecting, testing, and applying pigment agents, you can achieve a professional and personalized appearance for your boat’s gelcoat. If you need assistance selecting pigments for your gelcoat contact the customer support team at Bottom Paint Store 888-505-2313 or via live chat found at bottompaintstore.com
Maintaining the gel coat on your boat is essential to keep it looking its best and protecting the underlying fiberglass from the elements. Regular upkeep not only enhances the appearance of your boat but also extends the lifespan of the gel coat. We hope these practical tips help you maintain your gel coat effectively so that it lasts as long as possible.
Wash Regularly
The simplest and most effective way to maintain your boat’s gel coat is by washing it regularly. Saltwater, bird droppings, and dirt can cause significant damage if left unchecked. Use a mild marine soap and a soft brush or sponge to gently clean the surface. Avoid household detergents as they can strip away waxes and potentially damage the gel coat.
Apply a Quality Marine Wax
After washing, applying a high-quality marine wax is crucial. Wax provides a protective barrier against UV rays, salt, and pollutants. Apply wax at least twice a year—more often if your boat is exposed to harsh conditions regularly. Ensure the gel coat is completely dry and free of contaminants before applying wax in a circular motion using a soft cloth or buffer.
Designed to remove HEAVY oxidation, chalking, fading, minor scratches, rust and exhaust stains; plus provide protection on fiberglass/gelcoat.
Address Stains Immediately
Stains from leaves, bird droppings, and other natural elements can penetrate the gel coat if not removed promptly. For tough stains, use a specially formulated gel coat stain remover. Always test any cleaning solution on a small, inconspicuous area first to ensure it doesn’t harm the finish.
Inspect and Repair Any Chips or Scratches
Regular inspections can catch minor chips and scratches before they develop into larger issues. Small imperfections in the gel coat can be repaired using a gel coat repair kit. Clean the area thoroughly, apply the gel coat, and sand it down once cured to ensure it matches the level and smoothness of the surrounding area.
If you are wondering how to repair fiberglass or gelcoat on a boat then this Gelcoat Putty is the product to use, and the easiest way to fix it.
Avoid Long-Term Sun Exposure
Prolonged exposure to the sun can lead to fading and weakening of the gel coat. Whenever possible, store your boat under a cover or in a shaded area when not in use. If indoor storage isn’t an option, consider using a quality boat cover or tarp to protect against UV damage.
Regularly Check for Osmotic Blisters
Osmotic blisters can occur when water infiltrates the gel coat, leading to larger structural issues if left untreated. Inspect your boat regularly for any signs of blistering. Early stages can often be managed by drying out the area and repairing with a fresh application of gel coat.
By following these routine maintenance tips, you can keep your boat’s gel coat in pristine condition, ensuring your vessel remains both beautiful and seaworthy for years to come. Regular care not only preserves the integrity and aesthetics of your boat but also enhances its long-term value and performance on the water. If you have any questions or need help selecting a product to help maintain your gel coat please give the Bottom Paint Store customer support team a call 888.505.2313.
We get asked a lot of questions about applying gel coat so we thought we would offer this guide as a way to help you understand one of the best methods, gel coat spray guns. Gel coat spray guns are invaluable tools for achieving professional finishes in gel coating projects. Whether you’re a seasoned pro or a DIY enthusiast, understanding how these spray guns work and how to choose the right one can make a significant difference in your project’s outcome. In this guide, we’ll cover everything you need to know about gel coat spray guns, from their types and benefits to safety precautions and maintenance tips.
What is a Gel Coat Spray Gun?
Let’s start off by explaining that a gel coat spray gun is a specialized tool designed for applying gel coat, a type of resinous material, onto surfaces to create a smooth and durable finish. These guns atomize the gel coat, breaking it down into tiny droplets that are then sprayed evenly onto the surface, ensuring an even coating.
Types of Gel Coat Spray Guns
There are two main types of gel coat spray guns: conventional and HVLP (High Volume Low Pressure). Conventional spray guns use high pressure to atomize the gel coat, while HVLP guns use lower pressure, resulting in less overspray and a more efficient use of material.
Benefits of Using a Gel Coat Spray Gun
Gel coat spray guns allow for quick and efficient application, saving time and effort. The atomized spray creates a smooth and uniform coating, reducing the need for sanding and polishing. They also use less material compared to traditional methods, saving money in the long run.
Choosing the Right Gel Coat Spray Gun
When deciding which one is right for you, consider the size of your project, the type of gel coat you’re using, and your budget. It’s also important to choose one that is compatible with your compressor and other equipment.
Safety Precautions
Always wear protective gear, such as a respirator, goggles, and gloves, to protect yourself from fumes and overspray. Work in a well-ventilated area and follow the manufacturer’s instructions for proper use.
Using a Gel Coat Spray Gun
We’re often asked if it is difficult to use a gel coat spray gun. It really depends, it can be challenging for beginners, but with practice and proper technique, it becomes easier over time. Here are a few factors that can affect the difficulty level:
Skill level: If you’re new to spray painting or using spray guns in general, there will be a learning curve. Familiarizing yourself with the equipment and practicing on scrap materials can help improve your skills.
Adjusting settings: Gel coat spray guns typically have adjustable settings for things like air pressure, fluid flow, and fan pattern. Learning how to properly adjust these settings for your specific project and materials is crucial for achieving desired results. Again, practice before applying on your boat. You’ll be glad you did.
Cleaning and Maintenance
To keep your gel coat spray gun in good condition, clean it thoroughly after each use. Use a solvent recommended by the manufacturer to remove any gel coat residue. Regularly inspect the gun for signs of wear and tear and replace any damaged parts as needed.
As you can tell, gel coat spray guns are essential tools for achieving professional finishes in gel coating projects. By understanding how they work and following best practices for their use and maintenance, you can ensure a smooth and durable finish for your projects. If you have any questions about gel coat for boats contact our technical services team via Live Chat or by calling 888-505-2313.
Gel coat repair kits play a vital role in ensuring that boat owners can easily maintain the impeccable appearance of their vessels. These kits are specifically designed for simplicity and effectiveness, making them accessible even to individuals with limited experience in boat maintenance.
Comprehensive in nature, gel coat repair kits typically include a variety of components. These components often consist of gel coat in different colors to match the boat’s original finish, along with hardener for curing and application tools like brushes or syringes. With these kits, boat owners can address minor damages in a convenient and hassle-free manner. Whether it’s a small scratch, chip, or a more significant gouge, the right tools can be found within the kit to effectively address the specific issue at hand.
The application process of gel coat repair kits is designed to be straightforward, generally accompanied by clear instructions. Users can easily mix the components, apply the gel coat mixture to the damaged area, and allow it to cure. As a result, a seamless integration with the existing surface is achieved, creating a durable and smooth finish. This not only restores the gel coat’s integrity but also prevents further deterioration, ensuring the long-term protection of the boat.
From a financial perspective, gel coat repair kits offer a cost-effective solution for maintaining a boat’s appearance. By proactively addressing minor damages, boat owners can avoid more extensive and expensive repairs in the future. This empowers boat enthusiasts to navigate the seas with a sense of pride, knowing they have a reliable solution on board to keep their vessel looking as good as new.
In summary, gel coat repair kits are essential tools for boat owners. They provide an easy and effective solution for maintaining the appearance of boats, regardless of the owner’s level of experience. With their comprehensive nature and straightforward application process, these kits enable boat enthusiasts to address minor damages promptly and cost-effectively. By using gel coat repair kits, boat owners can maintain the integrity of their vessel’s finish, enhance its longevity, and navigate the waters with confidence.
Use gelcoat when you are repairing or restoring the original fiberglass surface and want a thick, durable finish that matches the boat’s existing gelcoat. Use boat paint when you want an easier refinishing option, a new color, or a coating system designed for topsides, decks, or below-the-waterline protection.
For most fiberglass boat owners, the right choice depends on the condition of the surface, where the coating will be used, and how much preparation and finishing work you want to do. Gelcoat is often best for fiberglass repairs and original-style restoration, while marine paint is often easier for cosmetic updates, color changes, and ongoing maintenance.
Gelcoat can restore the original fiberglass-style finish when properly sprayed, cured, sanded, and polished.
DIY topside refinishing
Boat paint
One-part topside paints are generally easier for boat owners to apply with brush, roller, or spray methods.
Fixing below-waterline fiberglass damage
Fiberglass repair, barrier coat, then bottom paint
The damaged area should be repaired and sealed before applying the proper underwater coating system.
What to Consider Before Choosing Gelcoat or Boat Paint
Before deciding between gelcoat and boat paint, look at the surface condition, location of the repair, desired finish, and how the boat is used. If the existing gelcoat is only faded or lightly oxidized, it may be possible to restore it with cleaning, compounding, and polishing before applying new coating.
If the surface has chips, gouges, cracks, or exposed fiberglass, gelcoat repair may be the better first step. If the surface is sound but unattractive, stained, or ready for a new color, a marine paint system may be more practical. For underwater hull areas, use products designed for below-the-waterline applications, such as barrier coat and antifouling bottom paint.
Common Questions About Gelcoat vs Boat Paint
Is gelcoat better than boat paint?
Gelcoat is better when repairing or restoring a fiberglass boat’s original surface. Boat paint is often better when you want to refinish, change color, or apply a coating designed for topsides, decks, or underwater protection. The better choice depends on the project, not just the product.
Can you paint over gelcoat?
Yes, you can paint over gelcoat if the surface is clean, dry, sound, sanded, and properly prepared. Faded or oxidized gelcoat should be cleaned and sanded before painting, and some projects may require primer for proper adhesion and long-term performance.
Can you apply gelcoat over paint?
Gelcoat should generally not be applied over standard boat paint unless the product manufacturer specifically allows it. Gelcoat is usually applied over fiberglass, properly prepared gelcoat, or compatible repair materials. If the surface is painted, the paint may need to be removed before gelcoat repair.
Should I restore faded gelcoat or repaint the boat?
If the gelcoat is faded but still thick and intact, try cleaning, compounding, and polishing first. If the gelcoat is badly worn, cracked, thin, stained, or difficult to restore, repainting or re-gelcoating may be a better option.
What is the difference between gelcoat and topside paint?
Gelcoat is the thick outer finish commonly found on fiberglass boats. Topside paint is a marine coating used above the waterline on hull sides, cabins, decks, and trim. Topside paint is often easier to apply for refinishing, while gelcoat is commonly used for fiberglass repairs and original-style restoration.
Can gelcoat be used below the waterline?
Gelcoat is used on fiberglass hulls, but it is not the same as antifouling bottom paint. If the boat stays in the water, the underwater hull usually needs the proper bottom paint system to help reduce marine growth.
Does boat paint last longer than gelcoat?
It depends on the product, surface preparation, exposure, maintenance, and where the coating is used. A properly maintained gelcoat surface can last many years, while a high-quality marine paint system can also provide long-lasting protection when applied correctly.
Is gelcoat harder to apply than boat paint?
Gelcoat is usually more difficult to apply and finish than one-part boat paint. Gelcoat often requires accurate catalyst mixing, careful film thickness, curing, sanding, compounding, and polishing. Many boat paints are easier for DIY users, especially for topside refinishing.
Can I use automotive paint instead of boat paint?
Automotive paint is not usually the best choice for boats because marine coatings are designed for water, UV exposure, salt, abrasion, and marine conditions. For best results, use a coating system made for the surface and environment where the boat will be used.
Do I need primer before painting over gelcoat?
Some marine paints can be applied over properly prepared gelcoat, while others require primer. Primer may improve adhesion, help seal repairs, and create a better surface for the final coating. Always follow the paint manufacturer’s instructions for surface preparation and primer requirements.
Recommended Gelcoat, Boat Paint, and Repair Supplies
Bottom Paint Store carries gelcoat repair products, marine topside paints, bottom paints, primers, barrier coats, fiberglass repair materials, fairing compounds, sandpaper, solvents, and application supplies. The right product depends on whether you are repairing fiberglass, restoring gelcoat, repainting topsides, refinishing decks, or protecting the bottom of the boat.
Gelcoat vs Boat Paint: Which One Should You Choose?
Choose Gelcoat if you’re repairing or restoring a fiberglass surface and need a thick, durable, original-style finish that can be sanded and polished.
Choose Boat Paint if you want a simpler application, faster results, or a cosmetic refresh—especially on larger surfaces.
Use paint above the waterline for ease and appearance; use bottom paint below the waterline for antifouling protection.
Bottom line:Gelcoat excels at repairs and durability, while boat paint is best for ease of application and color changes.
Tip:Gelcoat is not antifouling—boats kept in the water still require proper bottom paint below the waterline.
When it comes to boat repair and maintenance, choosing the right kind of coating is crucial to ensure the longevity and overall aesthetics of your vessel. Gelcoat and boat paint are two of the most used coatings for boats, but what are their differences? Which one should you use? In this blog post, we’ll explore and compare the features of gelcoat and boat paint to help you make an informed decision.
First, let’s define what gelcoat and boat paint are.
Gelcoat is a protective layer that’s applied directly to the boat’s fiberglass, while boat paint is a coating that can be applied over gelcoat, or directly to other materials like wood or aluminum. Gelcoat is known for its durability and resistance to water, UV rays, and harsh weather conditions. However, it can scratch and crack over time if it is not maintained properly. On the other hand, boat paint offers more flexibility in terms of colors and finish, however it may require more maintenance and upkeep.
Gelcoat or Boat Paint Project Checklist
Identify whether the surface is fiberglass, existing gelcoat, old paint, wood, aluminum, or steel
Determine whether the project is above or below the waterline
Decide whether you are repairing damage, restoring shine, or changing color
Clean, dewax, sand, and prepare the surface before coating
Use gelcoat repair products for chips, gouges, and fiberglass cosmetic repairs
Use topside paint for above-waterline refinishing and color changes
Use bottom paint for underwater antifouling protection
Use primer or barrier coat when required by the coating system
Follow the manufacturer’s instructions for dry time, cure time, sanding, and recoat windows
Composition and Application
Gelcoat is a resin-based coating that is applied directly to the fiberglass surface of a boat during the manufacturing process. It is typically thick and durable, with a glossy finish that can be easily polished. Gelcoat can be pigmented to match different colors and styles, but it is usually white.
When it comes to application, gelcoat is best applied using a gelcoat spray gun or roller, while boat paint can be applied using a spray gun, roller, or brush. Gelcoat can be easily repaired by sanding the damaged area and reapplying the gelcoat, while boat paint repairs may require sanding, filling, and repainting the entire affected area for a seamless finish.
In terms of durability, gelcoat is known for its strength and can last for many years, while boat paint may require repainting every five to ten years, depending on the quality of the paint and the maintenance of the vessel. Gelcoat also blends into the fiberglass, providing a smoother finish that can hide minor imperfections, while boat paint may highlight any dents, cracks, or other irregularities on the surface.
When it comes to cost, gelcoat is generally less expensive than boat paint. However, depending on the quality and extent of the repair or maintenance needed, the cost can vary for both coatings. Gelcoat repairs can range from a few hundred dollars to thousands of dollars, while boat paint jobs can cost from a few thousand dollars to tens of thousands of dollars.
In conclusion, choosing between gelcoat and boat bottom paint depends on your preferences, needs, and budget. If you’re looking for a durable, low-maintenance coating that can blend into the fiberglass and withstand harsh weather conditions, gelcoat may be the better option for you. On the other hand, if you want more flexibility in terms of colors and finish, don’t mind the extra maintenance required, and can afford the cost, boat paint may be the way to go. Ultimately, it’s important to consult with a professional boat service provider to help you make the right decision for your vessel.
Assess the damage: Cosmetic damage can be fixed with gelcoat repair, while cracks or soft spots require fiberglass and epoxy repair first.
Prep thoroughly: Clean, grind, and feather damaged areas so new fiberglass and gelcoat bond properly.
Repair in layers: Rebuild structure with fiberglass and resin, then finish with gelcoat for protection and appearance.
Bottom line: Long-lasting fiberglass repairs depend on proper damage assessment, structural repair first, and careful surface finishing.
Tip: If the fiberglass flexes or feels soft, do not skip structural repair—gelcoat alone will not fix the problem.
Quick Answer: How Do You Repair a Fiberglass Boat?
To repair a fiberglass boat, first clean and sand the damaged area, remove loose or cracked material, then rebuild the surface using fiberglass cloth, resin, filler, or gelcoat depending on the severity of the damage. Small scratches and chips may only need gelcoat repair, while cracks, gouges, soft spots, and holes may require fiberglass reinforcement.
The most important part of any fiberglass boat repair is preparation. The damaged area must be clean, dry, sanded, and properly shaped before applying resin, fiberglass cloth, fairing compound, primer, or gelcoat. Skipping the prep work can lead to poor adhesion, visible repairs, or damage that returns later.
Best Repair Method by Type of Fiberglass Damage
Type of Damage
Recommended Repair
Why It Works
Light scratches
Wet sanding, buffing, and polishing
Restores the surface when the damage has not cut deeply into the gelcoat.
Use the correct repair material based on the depth and size of the damage.
Small cosmetic repairs and larger structural repairs require different products.
5. Let the repair cure
Allow the resin, filler, or gelcoat to cure according to the manufacturer’s directions.
Rushing the cure time can weaken the repair or make sanding and finishing more difficult.
6. Sand, fair, and finish
Sand the cured repair smooth, then apply gelcoat, primer, paint, or bottom paint as needed.
The final finish protects the repair and helps it match the surrounding surface.
What to Consider Before Repairing Fiberglass
Before starting a fiberglass boat repair, identify whether the damage is above or below the waterline, cosmetic or structural, and whether the area is dry. Repairs below the waterline need special attention because the finished surface must resist water intrusion and may also need barrier coat or bottom paint after the repair is complete.
For small gelcoat chips, scratches, and surface cracks, a gelcoat repair product may be enough. For deeper gouges, holes, and impact damage, you may need fiberglass cloth, resin, hardener, fairing compound, sandpaper, masking materials, and a finishing product such as gelcoat, topside paint, or bottom paint.
Common Questions About Fiberglass Boat Repair
Can you repair a fiberglass boat yourself?
Yes, many small fiberglass boat repairs can be handled by a careful DIY boat owner. Scratches, chips, minor cracks, and small gouges are usually manageable with the right materials and preparation. Larger holes, soft spots, or structural damage may require more advanced repair skills or professional help.
What is the best product to repair fiberglass boat damage?
The best product depends on the type of damage. Gelcoat paste or gelcoat repair putty is often used for small cosmetic chips. Fiberglass cloth and resin are better for holes and structural repairs. Fairing compound is used to smooth and shape the repaired area before finishing.
What is the difference between gelcoat repair and fiberglass repair?
Gelcoat repair fixes the outer cosmetic and protective surface of the boat. Fiberglass repair fixes the laminate underneath when the damage is deeper, cracked, punctured, or weakened. Many repairs require both: fiberglass for strength and gelcoat for the finished surface.
Do you need fiberglass cloth for every boat repair?
No. Fiberglass cloth is usually not needed for very small surface scratches or shallow gelcoat chips. It is used when the repair needs added strength, such as holes, deeper cracks, gouges, or areas where the fiberglass laminate has been damaged.
Can you use Bondo on a fiberglass boat?
Automotive body filler is not usually the best choice for marine fiberglass repairs, especially below the waterline. Marine-grade fillers, epoxy fillers, polyester fillers, fairing compounds, and fiberglass repair materials are better suited for boats because they are designed for wet and demanding marine environments.
How do you repair a hole in a fiberglass boat?
To repair a hole in a fiberglass boat, grind or sand the damaged area, taper the edges, clean the surface, then rebuild the area with layers of fiberglass cloth or mat and resin. Once cured, the repair is sanded, faired smooth, and finished with gelcoat, paint, or bottom paint.
Can you repair fiberglass below the waterline?
Yes, fiberglass below the waterline can be repaired, but the repair must be sealed and finished correctly to prevent water intrusion. Depending on the job, the repaired area may need epoxy barrier coat, primer, and antifouling bottom paint after the fiberglass work is complete.
How long does fiberglass boat repair take to cure?
Cure time depends on the repair product, temperature, humidity, hardener ratio, and thickness of the application. Always follow the manufacturer’s instructions before sanding, fairing, painting, or putting the boat back in the water.
Should I use epoxy resin or polyester resin for fiberglass boat repair?
Both epoxy and polyester resin are used in fiberglass boat repair. Epoxy typically provides excellent adhesion and water resistance, while polyester resin is commonly used with gelcoat systems. The best choice depends on the repair location, existing material, and final finish.
Recommended Fiberglass Repair Products
Bottom Paint Store carries fiberglass repair materials for small cosmetic fixes and larger boat repair projects, including gelcoat repair products, fiberglass cloth, fiberglass mat, polyester resin, epoxy resin, hardeners, fairing compounds, fillers, primers, and finishing coatings. Choosing the right product depends on the size of the damage, whether the repair is above or below the waterline, and whether the final surface will be gelcoated, painted, or bottom painted.
If you’re a boat enthusiast, you know that there’s nothing quite like the feeling of cruising out on the open water. But what do you do when your beloved vessel starts to show signs of wear and tear? If you have a fiberglass boat, you’re in luck. In this blog post, we’ll walk you through everything you need to know about repairing your fiberglass boat, from small cracks to large holes. So, whether you’re a seasoned pro or a complete novice, read on for our step-by-step guide on how to repair a fiberglass boat.
KEY TAKEWAYS
Clean the Area The first step in boat fiberglass repair is to clean the area that needs to be repaired. This step is important because it will allow the repair materials to bond properly with the existing fiberglass. Use a mild soap and water solution to clean the area and then dry it thoroughly with a clean cloth.
Cut Out the Damaged Area Once the area is clean, use a sharp knife or razor blade to cut out the damaged area. Be sure to cut away any loose or damaged fiberglass so that you have a clean, smooth surface to work with.
Apply the Repair Material There are a variety of repair materials that can be used for fiberglass boat repair. The type of material you use will depend on the size and severity of the damage. For small repairs, you can use a fiberglass repair kit; for larger repairs, you may need to use a sheet of fiberglass cloth and some resin. Follow the instructions that come with your chosen repair material to apply it to the damaged area.
Repairing Small Cracks and Scratches
One of the most common problems that boat owners face is small cracks and scratches in the hull. While these may not seem like a big deal at first, they can quickly turn into larger problems if left unaddressed. The good news is that small cracks and scratches are relatively easy to fix with some basic supplies.
Polyester Resin is a great choice for fiberglass repairs
Here’s what you’ll need:
-Fiberglass cloth -Resin -Hardener -Sandpaper -Putty knife or spreader -Measuring cup -Gloves -Eye protection
Once you have all of your supplies, follow these steps to repair small cracks and scratches in your fiberglass boat:
Clean the area around the crack or scratch with sandpaper to rough up the surface and allow the resin to adhere better.
Cut a piece of fiberglass cloth to size and lay it over the crack or scratch.
Mix together the resin and hardener in a measuring cup, according to the application guidelines.
Use a putty knife or spreader to apply the resin mixture over the fiberglass cloth, making sure to work it into any crevices.
Allow the resin to cure for 24 hours before sanding down any excess material.
Your fiberglass boat is as good as new!
Fixing Large Holes in Fiberglass Boats
While small cracks and scratches are relatively easy to fix, large holes can be much more challenging—but not impossible! With some patience and elbow grease, you can patch up even the biggest holes in your fiberglass boat hull. Here’s what you’ll need:
-Fiberglass cloth -Resin mixture (resin and hardener) -Putty knife or spreader -Sandpaper -Measuring cup -Gloves -Eye protection -Plywood (optional)
Primer, topside paint, barrier coat, or bottom paint when needed
Follow these steps to repair large holes in your fiberglass boat hull:
If necessary, use plywood to create a temporary patch for the hole until the resin has cured. This will help keep water out of the hole while you’re working on it.
Cut a piece of fiberglass cloth to size and lay it over the hole.
Use a putty knife or spreader to apply the resin mixture over the fiberglass cloth, making sure to work it into any crevices.
Allow the resin to cure for 24 hours before sanding down any excess material and removing any plywood patches.
Your fiberglass boat is as good as new!
Performing each step carefully—from inspection to final finishing—ensures a strong, durable fiberglass repair and restores your boat’s structural integrity and appearance.
Conclusion:
No matter how experienced you are as a boat owner, sooner or later you’re going to need to make some repairs—and if you have a fiberglass boat, that means getting familiar with some basic repair techniques. In this blog post, we’ve walked you through everything you need to know about repairing small cracks and scratches, as well as large holes in your hull. So, whether you’re dealing with cosmetic damage or something more serious, now you know how to fix it!
How to Apply Professional-Grade Exterior Gelcoat by Brush & Roller
Best for smaller areas and repairs: Brushing and rolling gelcoat works well when spraying isn’t practical or permitted.
Prep and mix precisely: Clean, de-wax, sand thoroughly, and measure MEKP accurately to avoid curing issues.
Apply thin, even coats: Use quality rollers/brushes and build thickness gradually, sanding lightly between coats if needed.
Bottom line: You can achieve a professional, durable gelcoat finish without spraying by focusing on prep, mix ratios, and controlled application.
Tip: Gelcoat won’t fully cure in open air—use a wax additive or PVA on the final coat, then wet-sand and polish for a smooth finish.
Professional Grade Exterior Gelcoat can be applied either by Spraying, Brushing or Rolling. This article will discuss how to apply the gelcoat with the brush and roller method. For a more comprehensive guide on How to Apply Gelcoat, please read this article. We will assume you have already read the article to learn about prepping the surface, sanding, and finishing the gelcoat.
Catalyzing Gelcoat with MEKP
All gelcoats MUST be catalyzed with MEKP to cure. This should be added after all other additives just prior to application. We suggest 1-1/4% to 1-1/2% by volume, i.e. 13-15 cc per quart. We do NOT recommend mixing more than 1 quart at a time. Darker colors need a little more catalyst for the same reaction, so you can catalyze those up to 2%. All Gelcoats purchased from the Bottom Paint Store come with MEKP. Refer to the catalyst chart located on the product page, the product label, or the one below.
One gallon of polyester resin weighs approximately 9.2 lbs. One gallon of gelcoat weighs approximately 10.5 lbs. The weight of MEKP 925 is 1.125 grams per cc. 30 drops is approximately equal to one cc.
cc = cubic centimeter. Oz = fluid ounce Note: Using drops for catalyst measurement is only an estimate. In critical applications MEKP should be measured using cc’s or fluid oz’s which are volume measurements. The percentages in the chart: 1% thru 2%, are percentages of resin or gelcoat by weight. The cc and oz values in the chart have been converted from weights of MEKP to volumes of MEKP.
NOTE: The catalyst level (MEKP) should not exceed 3.0% or fall below 1.2 for proper cure. Ideal range is 1.8% @ 77°F. Gel time at 1.8% MEKP is 10-17 minutes. This time element is dependent on material temperature, room temperature, humidity, air movement, and catalyst concentration. Gelcoat should not be used when temperature conditions are below 60°F, as curing may be adversely affected.
Be sure to have a good strategy when applying your gelcoat. Once you mix and catalyze, you have about 15 minutes to apply the gelcoat before it starts getting hard or starts to “gel.” The actual working time depends on the amount of catalyst and how hot the working conditions are. Anything below 60 degrees, and your gelcoat will not cure, but as you get warmer and warmer, your working time will decrease rapidly. At 70 degrees, you get 15 minutes, but at 90 degrees, you only get 5 minutes.
TIP: If you need more time to work, sit the can in some cold ice water to cool it down to 60 degrees to allow a little more working time.
Application
Brushing: Use a solvent resistant brush. The chemicals in the gelcoat can be harsh on materials not designed to withstand them. Using a solvent resistant brush should stop any brush materials from getting in the finished product.
TIP: Choose a natural bristle brush with tapered bristles that are not too stiff.
Apply gelcoat quickly using long brush strokes to help achieve an even thickness and to help remove trapped air pockets. Load the brush fully with gelcoat each time. Applying the gelcoat quickly will help you apply it to the correct thickness. Gelcoat applied too thin will not cure properly. Remember, this gelcoat has been catalyzed and the clock is ticking. Also, large amounts of gelcoat left in the container allows a buildup of exotherm and causes the gelcoat to cure too quickly. Once all the gelcoat is out of container and on the surface then you can spend time tidying up with the brush strokes.
TIP: Try to finish vertical areas with an upward brush stroke. This will help reduce sag.
Rolling: Use a solvent resistant 1/8 or 1/4 inch nap roller. Be sure not to use foam rollers; they tend to leave bubbles. Wrap the roller in painters’ tape and rip the tape off to remove loose fibers from the roller. Apply the gelcoat to the surface quickly. Remember, this gelcoat has been catalyzed and the clock is ticking. After wetting out a small area with the roller, use the tip of a brush to smooth out the stipple left by the roller. Move the brush in smooth strokes perpendicular to the direction that the roller moved. Be careful to not apply too much pressure during this step. Ask a friend to assist with the tipping to speed things along. When rolling or brushing on the second coat be sure to apply in the opposite direction from the previous coat. This allows for a uniform finish.
Overview
The 1st coat will consist of gelcoat and hardener only. Wait a half hour for the gelcoat to set. It should be tacky. It will not be fully cured yet.
The 2nd coat will consist of gelcoat, hardener, and wax additive sanding aid. 1 oz of sanding aid per quart or 4 oz per gallon. Sanding aid seals the surface from oxygen, causing the surface to dry tack free.
A wax additive is NOT used with HI UV Clear. You should only use a wax additive in the final application coat or if you are planning on applying only one coat.
If you followed all the steps correctly you should have a beautiful application of gelcoat! If you’re using our Professional Grade Exterior Gelcoat, you’ll be ready to sand and buff your freshly gelcoated surface after about 1- 3 hours.
If your jet ski or waverunner hull is made of fiberglass then gelcoat can be an excellent restoration option. Gel coating a jet ski is a great way to keep it looking new and protect the surface from scratches and dings. It’s also a relatively easy process that most people can do in a few hours. In this blog post, we’ll walk you through the steps of how to gelcoat a jet ski. We’ll also provide some tips on how to make the process go as smoothly as possible.
What is gelcoat and what does it do
Gelcoat is a type of resin that is used as a protective coating on many boats, jet skis, and wave runners. It is applied to the hull of the vessel in order to provide a shiny, smooth finish. In addition to its aesthetic benefits, gelcoat also helps to protect the hull from UV damage, scratches, and other types of wear and tear. In some cases, gelcoat can even help to repair minor damage to the hull. As a result, gelcoat is an essential part of any boat or jet ski owner’s arsenal. While gelcoat can help extend the life of your jet ski or wave runner, it is not indestructible. Over time, it can become dulled or scratched, and it may eventually need to be replaced.
How to clean and prep the jet ski surface before you start
To clean the jet ski, you’ll need a mild soap, a soft cloth, and a jet ski brush. Start by mixing the soap and warm water in a bucket. Then Wet the jet ski with the soapy water and use the brush to scrub away any dirt or grime. Rinse the jet ski off with clean water and dry it with a soft cloth. For tough grease and dirt spots you can use a degreaser. This will remove any dirt, grime or grease that could prevent the paint from adhering properly.
Finally, inspect the jet ski for any cracks, chips or other damage. If you notice any of these, make sure to get them repaired before applying gelcoat. Use a fine-grit sandpaper to smooth out any rough spots. Gel coat repair kits, scratch patch kits, gel coat paste, fiberglass repair kits come with everything you need for small repairs.
Applying the gelcoat to your jet ski, wave runner
Applying gelcoat to a jet ski is a great way to protect your investment. Gelcoat is a clear or colored coating that is applied to the surface of a jet ski to protect it from the elements. It is also used to give the jet ski a high gloss finish. Gelcoat is available in both spray and brush-on versions. The brush-on version is generally easier to apply, but the spray version will give you a more even coverage. When applying gelcoat, be sure to follow the manufacturer’s instructions carefully. In general, you will want to apply several thin coats rather than one thick coat. Be sure to allow each coat to dry completely before applying the next one. Once the gelcoat has been applied, you will need to buff it out to achieve a high gloss finish. Once the final coat of gelcoat has been applied, the jet ski should be allowed to cure for 24 hours before being launched.
It’s important to choose the right gelcoat. There are dozens of different formulations on the market, so it’s important to do your homework and consult your owner’s manual. Once you’ve selected the right gelcoat, the next step is to apply it correctly. One common mistake is to apply too much gelcoat, which can lead to runs and sagging. It’s important to apply a thin, even coat and then allow it to cure properly before sanding or buffing.
With these tips in mind, your gelcoat project should be easier. Just remember to take your time and follow all instructions carefully, and you’ll soon be enjoying your jet ski on the open water. If you have any questions about selecting the right gel coat for your watercraft, please call the Bottom Paint Store customer support team 888.505.2313.
There are many common fillers used with gelcoat and resin and here we’ll help you pick the one that is right for you.
When using putty, a good rule is not to go higher than 1/8″ thick without adding a layer of glass to prevent any issues. With the various fillers, for the right working consistency, you’ll want about 60-70% mix to resin ratio.
Milled Fibers: Finer than chopped glass, makes a harder putty that is strong and coarse.
Walnut Shells: Brown in color and preferred for wood putty or nonskid since it has large particles. Good Strength and darker pigment.
Phenolic Microballons
Microballoons or Microspheres: Phenolic spheres are generally plastic or glass and hollow, intact spheres that are lightweight. This is ideal for making fairing compounds. The Microballoons are a more expensive option for filler.
Fumed Silica: Also known as Cabosil FIller or Aerosil Filler. This is a hydrophilic fumed silica. Fumed Silica provides little change to weight, color, or physical properties after cure, used in resins and gelcoats to make them hang on vertical surfaces, (too much can cause porosity.)
Cotton Flock: Made from pieces of cotton and thickens to an off-white color. Great for bonding many substrates, especially wood. The mixture also creates a multipurpose adhesive for many other substrates in addition to providing excellent substrate wetting and penetrating characteristics. Increases impact and abrasion resistance.
Chopped Glass Fibers
Chopped Glass: These are the biggest pieces of fillers and are most popular for use with resin putty. Perfect for corners, crack resistant, and doesn’t affect pigmented gelcoat. 1/4″ glass fibers make the strongest glass reinforced putty.
Use gelcoat for surface repairs such as scratches, chips, gouges, and cosmetic damage where the fiberglass structure is still sound.
Prep thoroughly: Clean, grind or sand damaged areas, and remove wax or contaminants before applying gelcoat.
Apply in thin layers and allow proper curing between coats for best adhesion and finish quality.
Bottom line:Gelcoat is ideal for restoring appearance and protection, but structural damage requires fiberglass repair before gelcoat is applied.
Tip:Gelcoat exposed to air will remain tacky—use a wax additive or PVA on the final coat to achieve a full cure.
How Is Gelcoat Used to Repair Fiberglass Surfaces?
Gelcoat is used to repair fiberglass surfaces by filling, sealing, and refinishing the outer cosmetic layer of a fiberglass boat. It is commonly used for small chips, scratches, gouges, spider cracks, worn areas, and cosmetic damage where the fiberglass structure underneath is still sound.
Gelcoat is not a structural repair by itself. If the fiberglass is cracked deeply, soft, punctured, delaminated, or damaged below the surface, the fiberglass laminate should be repaired first with resin, fiberglass cloth, filler, or fairing compound. Gelcoat is then applied as the final protective and cosmetic surface.
Best Gelcoat Repair Method by Damage Type
Fiberglass Damage
Recommended Repair
Why It Works
Light surface scratches
Wet sanding, compounding, and polishing
If the gelcoat is not deeply damaged, the surface may be restored without adding new gelcoat.
Restore with wet sanding, compound, polish, and protection.
Crack exposes fiberglass fibers
No
Repair the fiberglass or fill the damage before applying gelcoat.
Soft, flexible, or spongy area
No
Inspect for deeper laminate or core damage before finishing.
Hole through the fiberglass
No
Rebuild with fiberglass cloth and resin, then fair and gelcoat.
Cosmetic repair above the waterline
Often yes
Color-match gelcoat, apply, cure, sand, and polish.
Repair below the waterline
Sometimes, but not by itself
Repair fiberglass, seal properly, and finish with the correct underwater coating system if needed.
What to Consider Before Using Gelcoat for Fiberglass Repair
Before using gelcoat, determine whether the repair is cosmetic or structural. Gelcoat is excellent for restoring the outside surface of a fiberglass boat, but it should not be used as a substitute for fiberglass cloth, resin, or filler when strength is needed.
You should also consider color matching, cure method, and location. A small white gelcoat repair above the waterline may be straightforward, while a highly visible colored repair may require tinting and careful blending. Repairs below the waterline may require additional sealing, primer, barrier coat, or bottom paint depending on the project.
Common Questions About Using Gelcoat to Repair Fiberglass
Can gelcoat be used to repair fiberglass?
Yes, gelcoat is commonly used to repair the outer surface of fiberglass boats. It works well for chips, scratches, gouges, and cosmetic repairs. If the fiberglass underneath is cracked, weak, or damaged, the structural repair should be completed before applying gelcoat.
Is gelcoat a structural repair?
No. Gelcoat is primarily a cosmetic and protective surface layer. It can seal and finish a repair, but it does not replace the strength of fiberglass cloth, resin, or laminate repair materials.
Can I use gelcoat over exposed fiberglass?
Gelcoat can be applied over properly prepared fiberglass, but exposed or damaged fiberglass may need resin, filler, or fairing compound first. The surface should be clean, dry, sanded, stable, and compatible before gelcoat is applied.
What is the difference between gelcoat repair and fiberglass repair?
Gelcoat repair fixes the outer finish of a fiberglass surface. Fiberglass repair fixes the laminate underneath when the damage is deeper, cracked, punctured, or weakened. Many boat repairs require both fiberglass repair for strength and gelcoat for the final appearance.
Can you brush gelcoat onto a fiberglass repair?
Yes, gelcoat can be brushed onto small fiberglass repairs. Brushing may leave texture or brush marks, so the cured gelcoat is often sanded, compounded, and polished afterward to blend with the surrounding surface.
Do you need wax in gelcoat for repairs?
Wax additive or PVA may be needed when gelcoat is used as a final coat. Unwaxed gelcoat can remain tacky when exposed to air, so the final coat may need an air-blocking method to cure properly.
How do you match gelcoat color?
Start by cleaning and polishing a small area near the repair, then compare the color to a gelcoat color chart, repair kit, or manufacturer color reference. Older gelcoat may have faded, so tinting or blending may be needed for the closest match.
Can gelcoat be used below the waterline?
Gelcoat is used on fiberglass hulls, but a below-waterline repair may also need proper sealing, barrier coat, primer, or bottom paint depending on how the boat is used. Gelcoat is not the same as antifouling bottom paint.
Why did my gelcoat repair stay tacky?
Gelcoat may stay tacky if unwaxed gelcoat was used without PVA or wax additive. It can also stay soft because of incorrect MEKPcatalyst ratio, poor mixing, low temperature, expired materials, or surface contamination.
Do you have to sand and polish gelcoat after repair?
Most gelcoat repairs need sanding, compounding, and polishing after curing if you want the repair to blend smoothly with the surrounding surface. This step removes excess material, smooths the repair, and restores gloss.
Recommended Gelcoat and Fiberglass Repair Supplies
Bottom Paint Store carries gelcoat repair kits, white and colored gelcoat, neutral gelcoat, MEKPcatalyst, wax additive, PVA, fiberglass cloth, fiberglass mat, polyester resin, epoxy resin, fillers, fairing compounds, sandpaper, polishing compound, cleaners, and related application supplies. The right product depends on the size of the repair, whether the fiberglass is structurally damaged, and whether the final surface needs to be color matched, painted, or bottom painted.
It’s no secret that fiberglass surfaces can be extremely fragile and susceptible to damage. Even the smallest nick or crack can quickly become a larger problem, leading to an unsightly and potentially hazardous mess. Fortunately, there is a fix for most common fiberglass issues – gelcoat! This article will explain what gelcoat is, how it can be used to repair fiberglass surfaces, and some of its benefits. Keep reading to learn more!
What is gel coat?
Gelcoat is a specialized resin and is popular as a surface coating in the fabrication and repair of fiberglass-based products and can also be used to patch existing gel coat, fiberglass repairs, and new construction and repair projects. Gelcoat is extremely durable and provides a high-quality finish to visible surfaces making it a popular solution for damages to fiberglass surfaces such as covering up blemishes, patching small holes, filling cracks, and renewing surface shine. Gelcoat is often referred to as a one-stop solution for almost all types of damages on fiberglass surfaces such as, boats, jet skis, wave runners, swimming pools, hot tubs, showers and more.
Gelcoat for Swimming Pools
If you have a fiberglass pool then its surface is made of gelcoat, a liquid-colored resin that is applied to the pool shell. Gelcoat is the considered one of the most durable pool surfaces, typically lasting several decades, depending on maintenance, wear and tear, and the quality of the surface. Concrete pools need to be refinished about every ten years or so.
One of the more common areas of a fiberglass pool that needs to be refinished over time are the pool steps which can fade after exposure to pool chemicals, weather and UV rays. For more information please refer to our How to Gelcoat your Fiberglass Pool Steps article.
Gelcoat for Shower Stalls, Bathtubs, and Hot tubs
Cracks, holes, chips, and stains in showers and tubs made from fiberglass can be repaired with gelcoat. A common rule of thumb is if the hole is smaller than 1/2 inch, you should be able to make the repairs yourself; if it is a larger hole, then it may require the replacement of the surface or unit.
Fixing the damaged area requires applying two-part epoxy that hardens to the strength of the surrounding surface.
Gelcoat for a Fiberglass Deck
Applying gelcoat to a fiberglass deck is a great way to protect the surface from UV damage and environmental elements. Gelcoat is a clear or tinted resin that is applied to the surface of the deck, creating a protective barrier. The gelcoat will need to be reapplied every few years in order to maintain its effectiveness. When applying gelcoat, it is important to use a natural bristle brush in order to avoid damaging the fibers of the deck. In addition, gelcoat should be applied in thin coats in order to avoid runs and sags. With proper application, gelcoat can provide many years of protection for your fiberglass deck.
One of the most common ways to refinish a fiberglass deck is with a two-part polyurethane, as the results will provide a finish that will look as good as and should last at as long as the original gelcoat.
Re-gelcoating a Boat Fiberglass Hull
Regularly waxed gelcoat can last up to 15 years, depending on how well you take care of your boats hull and exposure to UV rays. If your hull is showing signs of damage such as cracking or is no longer retaining its gloss, and has chalky white powder on the surface, then it is time to re-gelcoat your hull. Dewaxer is perfect for dewaxing the hull and effectively cleaning up paint supplies.
Repairing a Fiberglass Boat
Repairing a fiberglass boat is not as difficult as it may seem. In fact, with the right materials and some basic knowledge, you can easily repair gelcoat cracks and holes. The first step is to clean the area around the crack or hole. This will help to ensure that the repair area is free of debris and dirt. Next, use a gelcoat patch kit to apply a thin layer of gelcoat to the damaged area. Once the gelcoat has cured, sand it down until it is flush with the surrounding area. Finally, apply a fresh coat of paint to protect the gelcoat from UV rays and weathering. With some patience and attention to detail, you can easily repair gelcoat cracks and holes yourself.
Be Prepared for your Gelcoat Project
Using gelcoat can be an excellent solution for repairing and renewing fiberglass-based surfaces. Gelcoat is sometimes referred to as marine paint for fiberglass, however it is not a paint, so if you are unfamiliar with applying gelcoat, please see our numerous how to articles as it can be difficult to apply and achieve optimal results for first time users. You can also contact Bottom Paint Store’s technical team from 8:30-5:00pm EST Monday through Friday.
Webbing Solution is a clear liquid added to gelcoat to obtain spatter or cobweb effects. It is mixed with a gelcoat of one color and sprayed onto a contrasting colored surface.
Decorative effects produced by the webbing mixture will vary, and relate directly to techniques or gun adjustments. A fine hairline spider web pattern results from plenty of air and scanty material flow. Coarse and splotchy patterns are created by fuller material flow and decreased air volume. While our webbing solution is only tested with gelcoat, customers do use with paint achieving similar results.
The manufacturer suggests on the initial coat you add the wax and while gelcoat is still tacky before it comes to a full air cure, you apply the contrast color of webbing (which should have the wax added too).
If you are applying webbing over a fully cured gelcoat, sand with 150 grit, clean with acetone, and then apply the webbing.
Mix 2 parts gelcoat to 1 part webbing. Mix proper amount MEK-P for the amount of gelcoat. Shoot at 10 to 12 PSI.
Add to colored gelcoat to obtain desired webbing effect. Test in an inconspicuous area to determine satisfactory results
Using Gelcoat Putty to Repair Spider Cracks & Gouges
Best for cosmetic damage: Gelcoat putty works well on spider cracks, chips, and surface gouges where the fiberglass structure is still solid.
Prep properly: Grind or open cracks slightly, clean thoroughly, and remove wax before applying putty.
Apply and finish carefully: Fill slightly proud of the surface, allow full cure, then sand smooth and polish.
Bottom line: Gelcoat putty restores appearance and surface protection, but structural cracks require fiberglass repair first.
Tip: For best color match, test a small area first and polish after sanding to blend the repair.
Gelcoat putty is an indispensable part of any boat owner’s toolkit, providing a simple way to make quick and reliable repairs on any gelcoat surface. Perfect for fixing anything from spider cracks to fill in gouges and scratches, and is an easy-to-use solution that leaves a smooth finish and every application has the potential to restore gelcoat surfaces and make them look like new again. This dependable material is simple enough even novice motorboat and sailboat owners can use it without having to take their vessels out of the water for professional repair. Gelcoat putty can help anyone keep their boats looking shipshape with minimal effort.
There are many ways to repair spider cracks in boats, using our Gelcoat Repair Putty is an easy and fast way of doing it!
First, you will need to determine your spider cracks are only that, spider cracks. To do so, you will need to inspect the area for any sign of broken support. If the surface is steady and looks solid, then you have spider cracks.
In order to properly fix any spider cracks, you will have to open the cracks to fill them up correctly. This can be done by using a Dremel. Once the crack is open and it has a good size you can sand and clean the area. For cleaning, you may use acetone or soap and water.
Now, you are ready to use the Gelcoat Putty. Mix in a 1-1/2% ratio of MEK-P Catalyst into the putty and mix it properly. Use a putty knife to fill in the spider cracks. Once dry, sand the surface to a smooth finish.
For filling gauges and cracks, some tips:
This product uses MEKP, just like gelcoat so your working time is 8-18 minutes, depending on temperature. If catalyzed at 1% and it is in perfect conditions (77 F) you have a longer work time. To extend work time cool product down before use.
If filling holes, fill a little high to allow for shrinkage. Once it dries you can easily smooth it out with sandpaper. Recommended thickness at 1/4″.
Tip: You can apply gelcoat to match the color of your boat over the repair, or you can use our pigments to tint the gelcoat putty and complete the repair all at once!
Gelcoat does not fully cure without first supplementing it with a surfacing agent or wax additive sanding aid. Gelcoat may be thinned for use in a Portable Preval Sprayer with styrene monomer. You can spray it with polyvinyl alcohol (PVA) before gelcoat reaches its gel stage (5-10 min.), or add 1oz per quart of a wax additive sanding aid.
PVA or Partall Film #10 is a release agent that helps with removing parts from a mold or can be used as a surfacing agent when using gelcoat without a wax additive (sanding aid).
PVA is soluble in water making it easy to wash off. Applying can be achieved by spraying or wiping the green liquid on with a sponge. It will foam slightly but dry to a clear, glossy shine. It can take 15-30 minutes depending on temperature.
For spraying gelcoat our FGCI brand does not recommend thinning.
Generally, you should not add more than 10% Styrene by volume. Patch Booster is an additive that will thin out gelcoat and not affect colors. Follow manufacturers instructions as added Mekp may be needed.
Another thinning alternative is the Duratec High Gloss Additive. This is used with gelcoat for many reasons. Mixed at a 50/50 ratio this will produce a high gloss finish and will serve as a thinner for your gelcoat, that is why this is commonly used when spraying gelcoat. In addition, you’ll omit any additional sanding aid. After waiting a full 24 hours you can buff when cured, for a hi-gloss use 600 or higher grit paper and buff with Aqua Buff 2000 compound. Follow the manufacturer’s technical data sheet as an extra hardener may be needed. Some customers use Styrene for thinning but the manufacturer warns it can affect the gelcoat colors although this is the most cost-effective option and doesn’t have the added wax.
If you are looking to remove some unwanted scratches on your boat or to bring back shine into your gelcoat, Aqua Buff is for you!
Aqua Buff is a polishing compound that we offer in two variations: Aqua Buff 1000-W and Aqua Buff 2000. It is mainly used as a way to remove heavy oxidation, sanding scratches, and swirl marks from gelcoat. There are no oils or polymers in Aqua Buff, so the surface you see is the true surface.
The Aqua Buff 1000-W is used for deep scratches and heavy oxidation. It has a blue-green color which is why is not recommended for white hulls. Use Aqua Buff 1000-F on white surfaces. Aqua Buff 1000-W removes 320 – 600 grit scratches.
Aqua Buff 2000 is used for finer scratches, swirl marks, and light oxidation. Use it to remove 1000 grit scratches and higher. Cleans and removes scratches from Fiber-Reinforced-Plastic parts, metals, and painted surfaces. It is strong enough for most uses and provides a shiny finish.
Application Instructions
Apply a small portion of Aqua–Buff 1000-W or 2000 on the surface using a brush or microfiber cloth (stick to a small area)
Use a spray bottle to mist the surface with water. Only use about a coin-size amount of compound per square foot.
Immediately machine buff* with a clean, damp, compound pad. Use wool or wool/blend pads only.
*Use machine buffers that generate at least 2500 rpm for best results.
For the best techniques and tips on how to apply Aqua Buff please watch the video below.
For aluminum decks: Use a marine-grade primer for aluminum followed by a durable non-skid topside paint.
For fiberglass decks: Apply non-skid polyurethane or deck coating for grip and UV resistance.
For wood decks: Use marine varnish, paint, or non-skid coatings depending on desired appearance and traction.
Bottom line: The best deck coating depends on the deck material, exposure to traffic, and need for non-slip safety.
Tip: Always choose a finish with UV resistance and proper traction—deck safety and durability matter more than appearance alone.
Over the lifetime of any boat there will come a time when the deck needs to be renewed. You have a choice of non-skid additives, or paints that already contain a nonskid compound. A non skid boat deck helps protect the surface as well as the occupants.
When looking for a non-skid surface you have many options. If your boat floor is currently gelcoat, you can re-gelcoat the surface with or without a non-skid additive. More information about gelcoat application can be found here. Gelcoat is more durable than paint and once a gelcoat surface is painted gelcoat will not adhere.
Customers painting the floor of a jon boat, frequently use the Aluma Hawk aluminum paint with a non skid additive. This paint serves as a paint and primer in one for your aluminum surface.
Interdeck boat deck paint is a non-skid deck paint by Interlux and offers an excellent slip resistant finish. It contains a fine aggregate and will apply easily on substrates. Its low sheen finish prevents dazzling that can be reflected by sunlight off decks. Interdeck is also easy to apply and available in numerous colors. The tough polyurethane resin protects decks against everyday wear and tear.
Depending on your paint choices, follow the manufacturers application instructions whether applying to aluminum, fiberglass, or wood to ensure best adhesion and slip resistance.
For cleaning the teak on your boat deck, JustTeak™ is a marine-grade teak cleaning system is designed to rejuvenate your teak quickly and easily. JustTeak™ will clean, brighten, and once sealed protect your teak decking. We have an application instructions video How to clean and protect the teak on your boat.
A livewell is a tank found on many fishing boats that is used to keep bait and caught fish alive. It works by pumping fresh water from the surrounding body into the tank, as well as keeping the water aerated.
Most live wells on boats are made of fiberglass and usually coated with gelcoat. For more information on applying gelcoat see our How to Apply Gelcoat article.
In the case that your live well is aluminum you can apply Aluma Hawk, available in white, blue, grey, black, sand and jon boat green to the aluminum surface.
For most paints, in order to guarantee efficacy, the only way we recommend changing the color of paints is to mix like paints, ie. Mixing Aluma Hawk with Aluma Hawk. We do not recommend addition of “universal” tints or pigments into our products. Many customers desire an antifouling paint in a deep, dark blue and this can be achieved by mixing blue and black.
Gel coats and resins can have a tint added, no more than 1 oz per quart, which can limit the effect. Another option is to mix two gelcoat colors, such as white and red for pink.
Ideal Temperatures for Applying Paints and Gelcoats
Best temperature range: Most marine paints and gelcoats apply best between 50°F and 85°F, with optimal results around 65–80°F.
Avoid cold conditions: Low temperatures slow curing and can cause poor adhesion or soft finishes.
Avoid excessive heat: High temperatures can cause rapid solvent flash-off, roller marks, and poor leveling.
Bottom line: Proper temperature—and stable conditions during curing—are critical for durability, appearance, and full cure.
Tip: Always consider surface temperature and overnight lows, not just daytime air temperature, before applying coatings.
When applying coatings in cooler temperatures it is important that you meet the minimum temperature requirements. This information can typically be found in the products technical data sheet, or on the can label.
As a general rule, coatings should be applied in good weather when air and surface temperatures are above 50°F (10°C) for most paints and 60°F (16°C) for epoxy, resin, and gelcoats . Surface temperature must be a least 50°F (10°C) above dew point. For optimum application properties, bring material to 70-80°F (21-27°C) temperature range prior to mixing and application.
Tips:
Make sure to store the coatings inside to keep the temperature in the optimal range prior to application.
Do not let coatings freeze, as this may alter the chemical integrity of the products.
In warm (hot) conditions be sure to keep the coatings out of direct sunlight exposure.
Coatings such as resins and gelcoats that require MEKp to be added for curing will require more MEKp in cooler conditions, and less MEKp in warmer conditions. See the guide below, but refer to the specific coating’s technical data sheet for detailed information:
Match the tip size to the coating thickness: Thicker materials like gelcoat and high-build primers require larger tips, while thinner paints need smaller tips.
Follow manufacturer guidance first: Always start with the recommended nozzle range listed on the product data sheet.
Adjust for spray method: HVLP guns typically use larger tips than conventional spray guns for the same material.
Bottom line: Choosing the correct nozzle tip size ensures proper atomization, even coverage, and fewer defects.
Tip: If the material sprays dry, sputters, or requires excessive thinning, the nozzle tip is likely too small.
What Size Spray Gun Tip Is Best for Gelcoat?
Best Gelcoat Spray Gun Tip Sizes (Quick Answer)
• Most gelcoat applications: 2.0–2.5 mm
• Thick gelcoat or no thinning: 2.5–3.0 mm
• Thinned gelcoat: 1.8–2.0 mm
• Touch-ups / detail work: 1.4–1.8 mm
If you just want the right starting point: most gelcoat sprays best through a 2.0–2.5 mm tip/nozzle. Use the quick guide below to match your gelcoat thickness and the finish you want.
Gelcoat Tip Size Cheat Sheet
Most gelcoat applications: 2.0–2.5 mm
Thick gelcoat / minimal thinning: 2.5–3.0 mm
Thinned gelcoat (better atomization): 1.8–2.2 mm
Small repairs / detail work: 1.4–1.8 mm
Heavy flake gelcoat (if applicable): 2.8–3.5 mm
Pro tip: If your gelcoat is spitting, orange-peeling badly, or clogging the gun,
your tip is often too small (or the gelcoat is too thick). If you’re getting runs/sags, you may be over-applying
or using too large a tip for your material and technique.
Next: Use the chart below to dial in your tip size by use case and application style.
There are three main factors to consider when determining the size tip that will produce the best results.
1. First, examine the coating that will be sprayed. Put simply, heavier coatings will require a larger orifice size than lighter ones. For example, primers are usually thicker than the accompanying paint so you should use a 1.7 or 1.8 mm tip to prime most surfaces. Most painters will stay in the range of 1.2 to 2.0 mm unless the paint being applied is specialized. (See chart below.)
2. The next thing to consider is your project surface area. This determines the appropriate fan width that your sprayer will produce, that is, the shape in which the product will leave the gun nozzle. Airless spray guns have more control over the fan width than conventional spray guns because the coating is forced through the tip without being atomized by air. This causes the tip to have a large impact on the fan width and shape. Most boat projects consist of large surfaces and so a wide fan will increase the spray coverage and also provide the ability to spray close to the surface without too much build up. Smaller surfaces will require a small fan width to reduce overspray. This also makes it possible to spray further away from the surface without too much falloff because the fan is more focused.
3. Lastly, consider the spray gun that is being used. Make sure that the spray tip you plan on using will be supported by the gun. Most spray gun manufacturers will provide this information in their product overview. The Bottom Paint Store distributes ES Manufacturing Gelcoat Spray Guns. The ES G830 gun will support a range of 0.8 – 2.0 mm. The ES G100and G200gelcoat spray guns support a range of 0.8 – 7.1 mm tips. If you aren’t sure about your gun’s supported sizes, check with the gun manufacturer.
Nozzle Tip Size by Coating Type
Selecting the correct spray gun nozzle tip size depends on the viscosity and build of the coating being applied. Use the table below as a general guideline, and always confirm with the manufacturer’s technical data sheet.
Gelcoat Spray Nozzle Tip Size Chart
Gelcoat Type
Recommended Tip Size
Spray Method
Notes
Standard Gelcoat
2.0 – 2.5 mm
HVLP / Gravity Feed Gun
Common for most repairs and recoats. Requires thinning only if specified by manufacturer.
Tooling Gelcoat
2.5 – 3.0 mm
Pressure Pot / HVLP
Thicker, harder formula. Larger tip reduces clogging and ensures proper film build.
Gelcoat with Metal Flake
2.5 – 3.5 mm
Pressure Pot / Specialized Flake Gun
Flake can clog smaller tips. Stir constantly and maintain strong airflow.
Waxed Gelcoat
2.0 – 2.5 mm
HVLP / Gravity Feed Gun
Applies similar to standard gelcoat. Final coat only — cures tack-free.
Unwaxed Gelcoat
2.0 – 2.5 mm
HVLP / Gravity Feed Gun
Leaves tacky surface for recoating. Often followed by waxed topcoat.
Thickened / Patch Gelcoat
2.0 – 2.7 mm
HVLP / Gravity Feed Gun
Used for scratch and chip repairs. Usually brushed or dabbed, but can be sprayed with larger tips.
Common Spray Tip Sizes and Their UsesTip size (mm)Commonly Used for0.8Parting Films – PVA – very fine mist1.2Clear Coats – super fine finishes1.4All Around Tip – clears, base coat, single stage paints1.6General Purpose – light to heavy viscosity materials1.8Primers – will apply primer quickly2.2 -2.5Gel Coats and Resins – for thick resins and not paintsApplication Tips
Air Pressure: Most HVLP guns need 35–65 PSI at the gun. Always check the spray gun’s manual.
Film Thickness: Aim for 18–22 mils total build (multiple passes of ~6–8 mils each).
Thinning: Only thin if specified — usually 5–10% with acetone or proprietary reducer. Too much thinning = runs + reduced durability.
Test First: Spray a test panel to confirm atomization before applying to your project.
Frequently Asked Questions (FAQ)
Why is selecting the right nozzle tip size important when applying gelcoat?
The nozzle tip size plays a crucial role in achieving a smooth and even finish when applying gelcoat. If the nozzle is too large or too small, it can cause uneven application, overspray, or a finish that is too thick or too thin. Selecting the right size ensures better control and optimal results.
What happens if I use the wrong nozzle tip size?
Using the wrong nozzle size can lead to several issues, such as poor gelcoat coverage, inconsistent texture, overspray, or excessive wastage. A nozzle that is too small may cause clogging or slow application, while one that is too large can result in an uneven layer of gelcoat.
How do I determine the right nozzle tip size for my gelcoat application?
The right nozzle tip size depends on factors such as the type of gelcoat, the thickness of the coating, and the specific spraying equipment you’re using. A general rule of thumb is that a 1.4mm to 1.8mm nozzle works well for most gelcoat applications. However, it’s essential to consult the manufacturer’s recommendations and consider your equipment specifications.
Can I use the same nozzle tip size for different types of gelcoat?
While you can use the same nozzle size for various gelcoats, some formulations might require adjustments. Thicker gelcoats may need a larger nozzle, while thinner ones may perform better with a smaller tip. Always test the setup before starting a large project to ensure a smooth application.
Should I use a different nozzle for each layer of gelcoat?
For some projects, especially those involving multiple layers of gelcoat, it may be helpful to use a different nozzle for each layer. A larger nozzle can be used for the base layer, while a smaller one may be better for final touch-ups and detailing. Always check the viscosity of the gelcoat before selecting the nozzle.
Can nozzle tip size affect the finish quality of my gelcoat project?
Yes, nozzle tip size can directly impact the finish quality. A nozzle that is too large may lead to excessive gelcoat application, while one that is too small may result in a patchy finish. For the best results, selecting the appropriate nozzle size ensures an even and smooth coat.
How do I clean my nozzle tip after using gelcoat?
Proper cleaning of the nozzle is essential to maintain performance and extend the life of your equipment. After each use, make sure to thoroughly clean the nozzle with the recommended solvent or cleaning solution to remove any leftover gelcoat or debris. Regular maintenance prevents clogs and ensures consistent application.
Can I use airless sprayers for gelcoat applications?
Yes, airless sprayers are commonly used for applying gelcoat, especially in large projects. When using an airless sprayer, make sure to select the appropriate nozzle size, as recommended by the sprayer’s manufacturer or based on your gelcoat thickness.
How can I avoid overspray when selecting a nozzle tip size?
To reduce overspray, select a nozzle that provides the correct spray pattern and pressure for your gelcoat. Using a smaller tip and lower pressure settings can help prevent excess spray. Additionally, consider using a spray shield or mask to control overspray during application.
Typically the clear coat on a bass boat is meant to protect the metalflake. You can choose a clear paint or clear gelcoat.
Clear gelcoat is typically what bass boats use at the factory for UV protection over metalflake but gelcoat isn’t as easy to use as paint. Gelcoat typically covers 48 sq feet applied at 18 mils thick per gallon.
We are often asked if you can you gelcoat over gelcoat? If the surface is already covered with gelcoat, or if the surface is a fiberglass, or polyester resin, then you can. It is relatively easy to to apply gelcoat on top of gelcoat if you follow the instructions. If the surface is paint, then the paint would have to be removed before applying the gelcoat. It is important to remember not to completely rely on gelcoat as it you may still need to make repairs to your bass boat after applying gelcoat.
Choose the right texture: Use pre-mixed non-skid paint for consistency, or add non-skid additive to control aggressiveness.
Prep thoroughly: Clean, de-wax, and sand the surface so the non-skid coating bonds properly.
Apply evenly: Roll or broadcast the non-skid material evenly to avoid slick spots or overly abrasive areas.
Bottom line: Proper prep and controlled texture application are key to achieving a durable, safe, non-slip surface.
Tip: Mask carefully before applying non-skid paint—clean edges make a big difference in the final appearance.
Non-skid paints can be used for various different applications and circumstances. The most common use of non-skid is on boats, or for marine use. Although that is the most common, it is used in many more conditions. Here are some other examples of how non skid paint can be used outside of the nautical setting.
The additive for gelcoat is extremely easy and adds just one extra step to the gelcoatapplication process. You simply mix the additive in with the gel coat before application and then apply. Alternative preferred application methods include using a flour sifter, powdered sugar shaker, or the punctured container itself, sprinkle the non skid into the gelcoat or paint. To use the container just punch holes in it with a nail or ice pick, overlappping the broadcasting stroke to provide a uniform pattern.
The amount you use is completely subjective and dependent on what your goal is; it is recommended to use no more than a quart of non-skid per gallon of paint. The available sizes of additive are a quart and a gallon.
