When looking at a scratch in the gelcoat, you need to determine whether it is a surface scratch or a deep scratch. The reason being is that surface scratches can easily be buffed with a rubbing compoundas opposed to deep scratches which take a couple more steps. As long as the gelcoat around the deep scratch is in good condition, you will be able to use gelcoat putty , requires mixing MEKP catalyst-once mixed properly it can be worked with a putty knife for filling, or you can make one using gelcoatand an aerosil filler/thickener. Once the filler is applied, the service will be uneven so sanding and polishing will be necessary. Customers report wet sanding with 2000 grit worked well. Everything about the repair of the scratch is fairly easy to do.
For deeper gouges, you will need to purchase gelcoat in various colors. Tints are available as well if custom matching larger quantities of gelcoat or paste. The kit will contain everything you need to do the job including some tints for matching. Some find the gouge needs to be scraped deeper with a screwdriver or Dremel tool to open it into a wide V to make sure the gelcoat has a place to settle and more permanent. If you simply cover the cracks they may continue to spread. The gelcoat that exists on the boat is already bonded with the laminates that are underneath. That being said, you will have to rough the surface up a bit with sand paper in order to give the paste something to stick to. Please note that you need to clean the surface with acetone after sanding to clean any contaminates off that may interfere with the filling process.
When the damage is a larger (like a screw hole) you made need3M’s Preminum Marine Filleror3M Marine High Strength Repair Filler. These are for bonding and filling repairs above or below the waterline and can be sanded. Some customers prefer to mix some thickener (cabosil)and gelcoat to a thick consistency. Both of these products can be applied with a spreader. If coating over with gelcoat be sure to leave space (about 1/8 inch) for the gelcoat. Splash Zone epoxy is easy to use for large areas underwater for all substrates.
If the underlying problem for the hairline cracks is not handled, re-gelcoating over them will only be a temporary fix, such as a soggy core or broken support. The cracking has stemmed from a crack below the gelcoat and in the fiberglass. This is one option to repair those cracks:
Using a Dremel tool, remove the gelcoat on either edge of the crack, all the way down its length. Basically this widens the gap and reveals the fiberglass layer beneath.
Determine if there is a crack in the fiberglass. If there is, it needs to be filled with a putty containing fiberglass strands. Duraglas Fiberglass Filler is one option.
Apply Gelcoat to the area. Can be brushed, rolled, or spray applied.
Once you have the gelcoat mixed, saving the hardener for last, begin to spread over the gouge with a plastic spreader. Since the paste will shrink slightly as it dries, make sure you put a little extra paste on the “wound”. A slight bulge will be ideal after the paste is applied. As the paste will not cure completely in the air, you will need to put a plastic film over it. If your kit does not have one, shrink wrap or wax paper will work. Tape the plastic/wax paper on all sides over the paste and let dry for 24 hours.
After the 24 hours are up, remove the plastic/wax paper. Take a piece of 400 grit sandpaper accompanied with a 3M sanding block and begin to level any areas that are raised and uneven. It will help if you have a bucket of water or water hose handy to wash away the excess material as you sand. Once you have completed the sanding with the 400 grit, you will need to now use a 600 grit sandpaper to go over the repair. The reason this is being done is to eliminate any scratches the 400 grit may have put in the repair and smooth it even more. You will continue this process moving up to a 800 grit and then a 1200 grit. Occasionally you will want to dry the repair area just to get an idea of the work you have done so far. At this point you can wax and buff the repair.
Identify the stain type first: Rust, tannin, fuel, mildew, and waterline stains each require different cleaners.
Start with the least aggressive method: Use a gelcoat-safe cleaner before moving to stain removers or light compounding.
Escalate carefully: For stubborn stains, use a dedicated marine stain remover or mild compound—avoid harsh abrasives.
Bottom line: Most gelcoat stains can be removed without sanding by matching the product to the stain.
Tip: After stain removal, apply a marine wax or sealant to protect gelcoat and reduce future staining.
A gelcoat surface is a very smooth, mirror-like finish when it is new. As gelcoat ages, it becomes porous which means the more easily it stains, the worse it looks and the harder it is to clean. Most all gelcoat can be restored, providing it is not completely worn through. Exhaust stains, like diesel, can develop on the surface of the Gel Coat. These stains can set in on the wax surface of the gel coat but the right cleaner can remove them. If the stain goes deeper, a bit of elbow grease will be needed.
Clean and inspect the surface with a wash with a mild cleaner like 3M’s boat soapor some alternative stronger cleaners if needed. After cleaning, dry and inspect surface for needs to be addressed: scratches, dings, cracking and crazing and to fix these flaws before rubbing out the gelcoat and restoring its shine. See the fiberglass/gelcoat repair section for options and the West System Videofor “how to” instruction.
Apply a fiberglass stain remover, like 3M Fiberglass Restorer and Wax, Mothers Marine Black Streak Remover, or 3M Marine Cleaner and Waxto the stained gelcoat area with a clean rag. The black/gray stains are the result of soot being deposited on your hull. It can happen when wet exhaust systems mix the exhaust gases with seawater and discharge those gases or dry exhaust systems discharging the soot directly into the atmosphere and it lands on your boat.
These liquid one-step products that combine a polish or compound with a wax remove oxidation, and protect the gelcoat in one step.
Wait 10-15 minutes. If the stain is simply laying on the surface of the Gel Coat, the stain will begin to loosen; rinse and inspect the results.
If the stain is lifting, repeat. If not, then something stronger like a more abrasive compound with a polisher may be needed; in that case a wax will be needed to restore the shine. Each time compound products are used, some of the gelcoat is removed. Use caution to use the least aggressive product that will get the job done. Frequently all that may be needed is to apply a protective coating of wax, such as 3M Ultra Performance Wax, Scotchgard Marine Wax, or Mothers Marine Synthetic Waxto help keep that shine.
Gel coat is a resin that is pigmented with color. The consistency of gel coat is very thick and is best applied with aspray gun.Metal flake is commonly used in clear gel coat for that “bass boat” look. Although it appears that the metal flakes are mixed into the base coat, they are usually mixed into the clear gel coat.
This can be applied over the colored gel coat and the metal flake is usually coated with clear gelcoat for added UV protection and to smooth the surface. The larger the metalflake, the more coats of clear gel coat it will often take to cover.
Usually it is recommended to use around 16 oz of metal flake per gallon of gel coat and personal preference plays a role as there us no magic ratio for adding flake. The typical bass boat will use 2-3 lbs of metal flake in the gel coat. Mix the gel coat inside a pail thoroughly with a paint stirrer to disperse the metal flakes. Stir it thoroughly and frequently during application to prevent the metal flakes from settling to the bottom.
Metal flake gelcoat is best applied using a gel coat spray gunto achieve an even coating and be sure to use an appropriate nozzle tip based on flake size.
You will need to disassemble the spray gun to clean it well as the flakes can lodge into small areas.
Our Gelcoat Color Match Chart is the perfect solution for any boat repair project. With a wide range of pre-mixed colors, our chart will help you find the right color tint to flawlessly make your gelcoat repairs. For smaller repairs, we offer convenient and easy-to-use repair kits with everything you need to match colors. For larger projects, we have gallons and quarts in 12 different colors ready for you to use. Plus, our neutral gelcoat lets you make any custom color you need when using the gel coat coloring agent. Get the perfect match for all your boat repair needs with Gelcoat Color Match Charts today. See the different colors of the pigments at the bottom of this article.
How Do You Match Gelcoat Color?
To match gelcoat color, start by identifying your boat manufacturer, model, year, and original gelcoat color if available. Then compare that information to a gelcoat color match chart or manufacturer color reference. Because gelcoat fades and oxidizes over time, the original factory color may not perfectly match the current color of an older boat.
For the best match, clean and compound a small area near the repair before comparing colors. This helps reveal the true gelcoat color underneath oxidation, chalking, stains, and surface fading. If the boat is older or heavily weathered, tinting or blending may be needed for the closest repair match.
Gelcoat Color Matching Methods
Matching Method
Best For
What to Consider
Boat manufacturer color code
Finding the original factory gelcoat color
Useful when the boat information is available, but older gelcoat may have faded from the original color.
Gelcoat color match chart
Comparing common gelcoat colors by brand, year, or shade
A chart is a helpful starting point, but screen colors and printed colors may not be exact.
Physical color chip or sample
More accurate visual comparison
Best viewed in natural light against a cleaned and polished area near the repair.
Custom tinting
Older boats, faded gelcoat, and visible repairs
May be needed when the original color no longer matches the boat’s current surface color.
Professional color matching
Large repairs or highly visible areas
Often the best choice when the repair must blend closely with surrounding gelcoat.
Best Gelcoat Match Approach by Repair Type
Repair Type
Recommended Approach
Why
Small chip or scratch
Use the closest matching gelcoat repair paste or kit
Small repairs are less noticeable and may not require a perfect custom match.
Visible topside repair
Clean, polish, compare colors, and tint if needed
Repairs above the waterline are easier to see, so color accuracy matters more.
Older oxidized gelcoat
Compound first, then match to the restored surface
Oxidation can make the boat look lighter, chalkier, or duller than the true color.
Large repair area
Use custom matching or professional help
Larger repairs are harder to hide if the gelcoat color is slightly off.
Below-waterline repair
Match if needed, then finish with the correct underwater coating system
Color may be less critical if the area will be covered by barrier coat or bottom paint.
White or off-white gelcoat
Compare carefully under natural light
Small differences in white, cream, ivory, and off-white shades can be very noticeable.
How to Use a Gelcoat Color Match Chart
Step
What to Do
Why It Matters
1. Identify the boat
Find the boat make, model, year, and any available factory color information.
Many gelcoat colors are tied to specific manufacturers and model years.
2. Clean the repair area
Remove wax, oxidation, stains, dirt, and surface contamination.
A dirty or oxidized surface can make the gelcoat look like the wrong color.
3. Polish a small area
Compound or polish near the repair before comparing colors.
This helps reveal the true color of the existing gelcoat.
4. Compare the chart or sample
Use the closest chart match, color chip, or physical sample.
Physical samples are usually more reliable than screen images.
5. Test before applying
Apply a small test patch or compare cured material before completing the repair.
Gelcoat can look different before and after curing, sanding, and polishing.
6. Blend and finish
Sand, compound, and polish the repaired area after curing.
Finishing helps the repaired area blend with the surrounding surface.
What to Consider Before Choosing a Gelcoat Color
Gelcoat color matching is not always as simple as choosing the original factory color. Sun exposure, oxidation, age, repairs, cleaning products, and previous polishing can all change how the boat’s surface looks. A color that matches the original chart may look too clean, too bright, or too dark next to older gelcoat.
White gelcoat can be especially difficult to match because there are many slight variations, including bright white, off-white, cream, ivory, oyster, and gray-white tones. For the closest match, compare the gelcoat color in natural daylight and test the repair material before applying it to a highly visible area.
Common Questions About Gelcoat Color Matching
How do I find my boat’s gelcoat color?
Start with the boat manufacturer, model, year, and any available hull or color information. Then compare that information to a gelcoat color match chart or manufacturer color reference. If the boat is older, clean and polish the surface before comparing colors.
Will the original gelcoat color match my boat exactly?
Not always. The original gelcoat color may be close, but older boats can fade, oxidize, stain, or weather over time. A factory color may need slight tinting or blending to match the boat’s current appearance.
Why is white gelcoat hard to match?
White gelcoat is difficult to match because small differences in tone are easy to see. Bright white, off-white, cream, ivory, and gray-white can look similar on a chart but noticeably different on a boat, especially in direct sunlight.
Can I tint gelcoat to match my boat?
Yes, gelcoat can often be tinted to improve the match. Tinting should be done carefully and in small amounts because a little pigment can change the color quickly. Always test the tinted gelcoat before applying it to the repair area.
Does gelcoat dry the same color it looks in the container?
Gelcoat may look different after it cures, sands, compounds, and polishes. For that reason, it is best to test a small amount and evaluate the cured, finished color before completing a visible repair.
Should I match gelcoat before or after polishing the boat?
Match gelcoat after cleaning and polishing a small area near the repair. Oxidized gelcoat can look chalky, faded, or lighter than the true color, which can lead to choosing the wrong shade.
Can I use a gelcoat color chart from my computer screen?
A screen chart can help narrow your options, but it should not be treated as an exact match. Screen brightness, monitor settings, lighting, and photo quality can all change how the color appears.
What if I cannot find my exact gelcoat color?
If you cannot find an exact gelcoat color, choose the closest match and consider tinting or blending. For large or highly visible repairs, professional color matching may be the best option.
Is gelcoat color matching important below the waterline?
Color matching may be less important below the waterline if the repair will be covered by barrier coat or bottom paint. The priority below the waterline is usually proper repair, sealing, and coating compatibility.
How can I make a gelcoat repair blend better?
Use the closest color match, prepare the surface properly, apply the repair carefully, and finish by wet sanding, compounding, and polishing. Feathering and polishing the repair area can help it blend with the surrounding gelcoat.
Recommended Gelcoat Color Matching Products and Supplies
Bottom Paint Store carries gelcoat repair kits, neutral gelcoat, white gelcoat, colored gelcoat, tinting pigments, MEKP catalyst, wax additive, PVA, sandpaper, polishing compound, cleaners, and application supplies. The right product depends on the boat color, size of the repair, surface condition, and whether the gelcoat needs to be tinted or finished after curing.
For smaller repairs, we offer a convenient and easy-to-use gelcoat repair kit with everything you need to match colors. For larger projects, we have have over 12 premixed colors of gel coat to choose from, in either gallons or quarts. Plus, our neutral gelcoat lets you make any custom color you need.
We are often asked how long does gel coat take to cure?
It really depends on several factors, for example, the type of gel coat used, the temperature and humidity of your environment, and the thickness of the application. Generally speaking, gel coat can take anywhere from a few hours to several days to fully cure.
Here are some general guidelines:
Initial Cure time: Gel coat typically reaches an initial cure within a few hours, usually around 2 to 4 hours. During this time, the gel coat becomes tack-free and can be touched without leaving fingerprints.
Gel Time: this refers to the time it takes for the gel coat to reach a semi-solid state where it can hold its shape and is no longer tacky to the touch. Gel time can vary based on the specific gel coat formulation but is usually within 6 to 12 hours.
Full Cure: this usually takes longer. It can take anywhere from 24 to 72 hours for the gel coat to completely cure and harden to its maximum strength and durability. However, some high-performance gel coats may require longer curing times to achieve their optimal properties.
Factors that can influence curing time include:
Temperature: Higher temperatures generally accelerate the curing process, while cooler temperatures can slow it down. Follow the manufacturer’s recommendations for curing temperature ranges.
Humidity: Higher humidity levels can also affect curing time. High humidity can extend the curing process, while low humidity may speed it up.
Thickness: Thicker applications of gel coat may take longer to cure due to the heat generated during the curing process. Thicker layers can also trap solvents that need to evaporate.
Catalyst/Hardener: Gel coat is usually catalyzed with a hardener to initiate the curing process. The amount and type of hardener used can impact the curing time.
Ventilation: Proper ventilation is essential during curing to ensure that any volatile solvents evaporate and don’t get trapped in the cured gel coat.
We recommend referring to the manufacturer’s instructions and guidelines, as curing times can vary based on the product’s formulation. It’s also important to consider the intended use of the gel-coated surface, as some applications may require longer curing times to ensure the best performance and durability.
How to match your gelcoat color?
We understand matching your gelcoat color can be a daunting task, however with the right tools and techniques, it can be done. The key is to start with a precise color match and then to carefully apply the gelcoat, ensuring that the new color blends seamlessly with the surrounding area. With patience and attention to detail, you can restore your boat’s gelcoat to its original luster or create a customized look that truly represents your personal style on the water.
Where to buy gel coat?
If you need assistance on where to buy gelcoat, Bottom Paint Store is available to answer your questions and help you select the right gelcoat for your needs. We have 100’s of colors and products to choose from.
Use gelcoat when repairing or restoring fiberglass surfaces and you want a thick, durable, original-style finish that can be sanded and polished.
Use marine paint instead for large cosmetic refinishing jobs where ease of application and faster turnaround matter more than thickness.
Below the waterline: Gelcoat is not antifouling—boats kept in the water still require proper bottom paint.
Bottom line: Gelcoat excels at repairs and long-term durability; marine paint excels at simplicity and full-boat color changes.
Tip: Gelcoat requires correct catalyst ratios and air-inhibition control (wax additive or PVA) to cure properly.
How Can You Tell if a Boat Has Gelcoat or Paint?
You can usually tell whether a boat has gelcoat or paint by inspecting the surface, checking for peeling, looking at scratches, testing a small hidden area, and reviewing the boat’s history. Gelcoat is the original molded finish on most fiberglass boats and is usually thicker, harder, and more polishable. Paint is a coating applied over the surface and may show peeling, brush marks, roller texture, or a visible edge where it was applied.
If the boat is fiberglass and has never been refinished, the surface is most likely gelcoat. If the finish has been changed, repainted, or repaired, it may have marine paint over the original gelcoat. Knowing the difference matters because gelcoat can often be compounded, polished, or repaired, while painted surfaces usually require a different repair and recoating process.
Gelcoat vs Paint Identification Guide
What to Check
Likely Gelcoat
Likely Paint
Boat material
Common on fiberglass boats as the original outer finish
May be applied over fiberglass, wood, aluminum, steel, or old gelcoat
Surface thickness
Usually thicker than paint and can often be sanded and polished
Usually a thinner coating layer over the original surface
Peeling or flaking
Gelcoat may crack or oxidize but does not usually peel like paint
Paint may peel, chip, lift, or flake when adhesion fails
Scratches
Scratches may show the same color underneath if the gelcoat is thick
Scratches may reveal a different color or original gelcoat underneath
Oxidation
Often turns chalky, dull, or faded and may improve with compounding
May fade, chalk, or lose gloss, but aggressive compounding can damage thin paint
Edges and seams
No obvious coating edge if it is original molded gelcoat
May show paint edges around hardware, tape lines, repairs, or masked areas
Brush or roller marks
Usually not visible on original molded gelcoat
May show brush marks, roller stipple, spray texture, or uneven coating thickness
Repair method
Often repaired with gelcoat paste, matching gelcoat, sanding, and polishing
Usually repaired by sanding, priming, and repainting with a compatible marine paint
Simple Ways to Check if Your Boat Has Gelcoat or Paint
Test
What to Do
What It May Tell You
Look for peeling
Inspect corners, chips, scratches, hardware edges, and damaged areas.
Peeling or lifting usually points to paint rather than original gelcoat.
Check a scratch
Look closely at a scratch or chip to see whether another color appears underneath.
A different color below the surface may mean the boat was painted.
Inspect around hardware
Look near cleats, rails, fittings, rub rails, hinges, and masked edges.
Paint may leave visible edges, tape lines, or build-up around hardware.
Try light compounding in a small area
Compound a small hidden or low-visibility spot carefully.
Oxidized gelcoat often improves noticeably, while thin paint may not tolerate aggressive compounding.
Look for brush or roller texture
View the surface from an angle in good light.
Brush marks, roller stipple, or uneven texture may indicate a painted surface.
Review the boat’s history
Check records, previous owner information, repair invoices, or manufacturer details.
A repaint, restoration, or color change usually means paint was applied over gelcoat.
Best Next Step Based on What You Find
What You Find
Likely Surface
Recommended Next Step
Dull, chalky fiberglass surface that improves with compounding
Oxidized gelcoat
Clean, compound, polish, and protect before deciding to repaint.
Peeling or flaking coating
Paint over gelcoat or another coating
Sand or remove loose paint, then repaint with a compatible marine coating system.
Small chips or gouges in fiberglass
Damaged gelcoat
Use gelcoat repair material, then sand, compound, and polish.
Scratches reveal a different color underneath
Painted surface
Identify the existing coating before sanding, priming, or repainting.
Old finish is faded but not peeling
Could be gelcoat or paint
Test a small area before using aggressive compounds, sandpaper, or solvents.
Below-waterline coating is wearing away
Likely bottom paint
Identify whether it is hard or ablative bottom paint before recoating.
What to Consider Before Repairing or Recoating
Before repairing, polishing, or repainting your boat, confirm whether you are working with gelcoat, topside paint, bottom paint, or another marine coating. The wrong repair method can create adhesion problems, color mismatch, sanding damage, or coating failure.
If the surface is gelcoat, you may be able to restore shine with cleaning, compounding, and polishing before repainting is necessary. If the surface is painted, be more cautious with aggressive sanding or buffing because paint is usually thinner than gelcoat and can be damaged more easily.
Common Questions About Identifying Gelcoat or Paint
Do all fiberglass boats have gelcoat?
Most fiberglass boats are originally built with gelcoat as the outer molded finish. However, a fiberglass boat may later be painted during repair, restoration, refinishing, or color changes.
Can a boat have paint over gelcoat?
Yes, many fiberglass boats have paint applied over the original gelcoat. This is common when the boat has been refinished, repaired, restored, or had its color changed.
How can I tell if my boat was repainted?
Look for peeling, tape lines, brush marks, roller texture, overspray, color differences in scratches, or coating edges around hardware. These signs often indicate that paint was applied over the original surface.
Does gelcoat peel like paint?
Gelcoat usually does not peel like paint. It may oxidize, fade, crack, chip, or become chalky, but peeling or flaking is more commonly associated with paint or another coating applied over the surface.
Can you polish gelcoat?
Yes, oxidized gelcoat can often be restored by cleaning, compounding, polishing, and waxing or sealing. This is one reason it is important to identify gelcoat before deciding to repaint.
Can you polish boat paint?
Some marine paints can be polished lightly, but painted surfaces are usually thinner than gelcoat and can be damaged by aggressive compounding or sanding. Always test a small area and follow the coating manufacturer’s recommendations.
Can you apply gelcoat over paint?
Gelcoat should generally not be applied over standard boat paint unless the manufacturer specifically allows it. Gelcoat is usually applied over fiberglass, existing gelcoat, or compatible repair materials, so paint may need to be removed first.
Can you paint over gelcoat?
Yes, you can paint over gelcoat if the surface is clean, dry, sound, dewaxed, sanded, and properly prepared. Some paint systems may also require primer for best adhesion and durability.
What if I cannot tell whether it is gelcoat or paint?
If you are unsure, test a small hidden area, inspect scratches and edges, review the boat’s history, or ask a marine repair professional. It is better to identify the surface before choosing cleaners, compounds, sandpaper, primer, gelcoat, or paint.
Is bottom paint the same as gelcoat?
No. Bottom paint is an antifouling coating used below the waterline to help reduce marine growth. Gelcoat is the original outer finish on many fiberglass boats. A boat can have gelcoat on the hull with bottom paint applied over the underwater portion.
Recommended Gelcoat and Boat Paint Supplies
Bottom Paint Store carries gelcoat repair products, marine topside paints, bottom paints, primers, barrier coats, polishing compounds, sandpaper, cleaners, solvents, waxes, and application supplies. The right product depends on whether your boat has original gelcoat, marine paint, bottom paint, or a coating system applied over the original surface.
Fiberglass is what is used as the base of the boat. These are the strands underneath the gelcoat that you typically do not see. (unless there is a gouge!) Over the fiberglass usually gelcoat is applied at the factory. If the surface is scratched gelcoat is the same color throughout; if the surface has been painted when scratched it will show what is underneath.
Need a repair?
If it is just a gouge and not penetrated all the way through the boat, then you would need to fill in the gouge with 3M premium marine filler (just one product that will work but our most popular for this use). After you have filled in the gouge and sanded it down, you would then apply the topcoat of gelcoat. (gelcoat is the top finish that you see on your entire boat.) Gelcoat is typically much thicker than a paint and is designed to protect the underlying fiberglass as well as provide a smooth shiny appearance. Be sure to leave the marine filler about 1/8″ lower than the surrounding gelcoat. This will allow you to apply enough gelcoat and be able to feather the surrounding area once your done. If you leave the marine filler flush, then once you apply the gelcoat you will have a lump on the area you are repairing (gelcoat should be thick enough or it could release from repair).
The amount that you will need is dependent on the size and number of gouges. If you have many gouges, you may consider buying a quart of gelcoat. However, the nice thing about the gelcoat repair kits is that they come with tints so that you can try to match your existing gelcoat color.
If you need to tint a quart our gallon to match see our available gelcoat tints, please note it isn’t recommended to use more than 1 oz of tint per quart or the curing of gelcoat could be effected.
What is gelcoat?
Gelcoat is a type of polymer that is used as a protective coating on boats and other watercraft. It is typically applied to the hull of the vessel, and it acts as a barrier against UV rays, salt water, and other elements. Gelcoat is available in a variety of colors and can be polished to a high shine. It is also one of the most durable materials used in boat construction, making it an ideal choice for those who want their vessel to look good for years to come.
Gelcoat is a liquid resin that is used to create a smooth, shiny surface on boats and other products.
What is difference between gel coat and paint?
Gelcoat is usually much thicker than paint and is engineered to protect the underlying fiberglass as well as provide a smooth shiny appearance. However, the nice thing about the gelcoat repair kits is that they come with tints so that you can try to match your existing gelcoat color. Paint is thinner and typically much easier to apply. Unlike paint, gelcoat will not adhere to existing paint, wood, metal or concrete. Gelcoat also has a limited shelf life of around 3-4 months at around 70 degrees whereas paints that are solvent-based can last up to 15 years while latex and water-based ones may last for up to 10 years.
Final thoughts
So, how do you know if your boat has gelcoat or paint? One method is to use rubbing alcohol on a white cloth and rub it over an inconspicuous area of the hull. If the surface starts to shine, then it’s likely that you have gelcoat. Another option is to take a piece of sandpaper and gently rub it over an area where the finish appears smooth. If the paper doesn’t snag and pull up any fibers from the surface, then it’s most likely gelcoat as well. With this information in hand, now you can properly care for your boat and keep its beautiful finish looking good for years to come! If you need assistance selecting the right gelcoat for your needs, contact technical support at Bottom Paint Store.
Prep is critical: Clean thoroughly, remove wax, and sand the surface so the gelcoat can properly bond.
Mix and catalyze correctly: Measure MEKP accurately and mix completely to avoid curing problems.
Apply in thin, controlled layers: Build thickness gradually rather than applying heavy coats.
Bottom line: Successful gelcoat application depends on proper surface prep, correct catalyst ratio, and controlled application.
Tip: Gelcoat exposed to air will remain tacky—use a wax additive or PVA on the final coat to ensure a full cure.
This is one of the questions Bottom Paint Store is asked the most. Let’s start with explaining that gelcoat is not a paint but a type of resin that is used to provide a protective layer over fiberglass.
Key takeaways on how to apply gelcoat:
Clean the repair area and all tools with acetone prior to application.
Do not work in direct sunlight. Choose a shady location or an overcast day.
Catalyze your material so that it has a longer pot life.
Apply the gelcoat using a brush or spray gun.
Apply gelcoat in 4-5 layers at approximately 5 mils each, allowing 15-20 minutes between layers for a total thickness of 20-25 mils.
Use a gelcoat thickness gauge to ensure proper thickness is achieved.
Once gel coat has tacked up, about 20 minutes after final layer has been applied, lay-up of the part can begin.
Here are the steps to apply gelcoat using a brush.
Below you will find a detailed gel coat preparation guide on how to apply gelcoat to your boat, RV, or other surfaces. The secret to a good finish is to apply the gelcoat properly. The application of gelcoat is pretty straightforward when you follow this guide.
Determine the Existing Surface: First thing you want to do is look at the surface on which you want gelcoat applied. If the surface is already coated with gelcoat, or if the surface is a fiberglass or polyester resin, then the application of gelcoat is a snap. If the surface is painted then the paint should be removed before the gelcoat is applied.
We offer pre-mixed colors of gelcoat, use this color chart as a guide for the available colors that we have.
Prepping the Surface: Remove rails, cleats, louvers, snaps, striping tape, etc. Duct tape off adjacent gunwale molding, and deck fittings you are unable to remove. **NOTE** Duct tape is recommended over masking tape because it provides better protection. Remove seals from the edges of parts or fittings when doing a repair around that part or fitting. Take steps to cover and protect the rest of the boat before starting. When working on the deck or cabin, tarp off the adjacent areas. 3M and UV tapes , and masking papers are recommended.
Sanding Existing Gel Coat: You want to sand the surface to make a mechanical bond to the gel coat. Our technicians suggest the use of Dyekum Steel Blue Dye to be really thorough. Steel Blue is a dye you’re going to wipe on or you can use the blue dye spray. If you don’t see the blue dye again, you know you’ve sanded it all properly. Start by sanding the surface with 150 grit or sandpaper. The heavier fast-cut grits (40/80/100) are used to feather sand and ground out a routed area prior to filling. Also, they are used for the first sanding of gouges, dock dings, scratches, and blisters. When sanding areas that have been filled with putty we suggest using 40 or 80 grit sandpaper, depending on how large the repair is. Once the fill area is level or contoured to the desired shape, sand with 100 grit paper to remove the course scratches from 40 or 80 grit. You should also feather the surrounding area of the gel coat repair with 220/330. At this point, the repair is ready to prep and spray/brush with gelcoat. Use 3M Abrasives for best results.
Preparing the Surface for Application: Next, you’re going to have to clean the surface. We encourage the use of Acetone, because it does not leave residue and evaporates easily. When the surface is clean, you want to get moving fairly quickly; if the surface is sitting for some amount of time, you want to re-clean the surface. Dust and dirt particles are your enemy here, so make sure you clean the surface thoroughly. Determine whether you need one or two gelcoat coats. If you change colors, it will require at least two gelcoat coats. If this is going over a patch, at least 2 coats are recommended to get a uniform surface. Otherwise, there will be only one coat.
Method of Application: Next, determine if you are going to brush, roll or spray your gelcoat so you can prepare the gelcoat for application. If you have Professional Grade Exterior Gelcoat you may either brush/roll or spray. When rolling on gelcoat be sure to use a 1/8 “or 1⁄4” solvent-resistant nap. Be sure not to use foam rollers because they tend to leave the bubbles. If you brush on the gel coat, make sure to use a solvent resistant brush.
Gel Coat Additives: You should also determine which additives you will use with your gelcoat application.
Wax Additive: Add up to 4 oz of Wax Additive per gallon 1 oz per quart for tack-free surface on the final coat, or if applying one coat a recommended film thickness. The Exterior Gelcoats that recommend a wax additive is included with purchase at Bottom Paint Store. (A wax additive is NOT used with Brushable Gel Coat or HI UV Clear.) You should only use a wax additive in the final application coat or if you are planning on only one coat.
Partall Film #10 PVA Surfacing Agent For Gel Coat: Use this product as a surfacing agent when using Gel Coat without wax additive and typically larger spray applications. Partall Film #10 is a polyvinyl alcohol (PVA) water/alcohol solution of water-soluble, film-forming materials. This parting film is particularly recommended as a parting agent for separation between polyester or epoxy resins and various mold surfaces. It is not recommended for use with resins containing water or giving off water during cure (i.e., phenolics) or with automotive finishes, as damage may occur. Partall Film #10 will not shrink and pull away from corners or curved surfaces. After the resin has dried, the film parts easily from the mold and is readily dissolved from the molded parts with water. An occasional coating of Partall Paste #2 is required on most mold surfaces before application of Partall Film #10. May be applied over gelcoat as a surface cure agent. (recommended for HI UV Clear since no wax should be added)
Patch Booster Gelcoat Additive is an additive that significantly improves the application, appearance, and longevity of gelcoat patches. Patch Booster eliminates the need to thin, side-promote, or add wax to gelcoat prior to patching. Formulation enhancements have lengthened the shelf life of a sealed can to (1) year while maintaining a sand-able cure in 1-3 hours. Do not use any other wax additive when using Patch Booster. Patch Booster should be used with Professional Grade Exterior Gel Coat. Another popular additive option is the Duratec Hi-Gloss Additive Clear, see the tech data sheet for mixing details for all items.
Catalyzing Gelcoat with MEKP: All gelcoat MUST be catalyzed with MEKP to cure. This should be added after all other additives just prior to application. Gelcoat requires Methyl Ethyl Ketone Peroxide or MEKP to enable the process of hardening. It’s a very small number. We suggest 1-1/4% to 1-1/2% by volume, i.e. 13-15 cc per quart. Darker colors need a little more catalyst for the same reaction, so you can catalyze up to 2%. All Gel Coats from Bottom Paint Store come with MEKP with each gelcoat purchase. Refer to the catalyst chart located on the product page for the gelcoat you are using or follow the label guidelines. As a general rule: 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. If you need more time to work, be sure to sit the can in some cold ice water to cool it down to 60 degrees to allow you a little more working time.
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.
1 ML = 1 CC
If using a wood mixing stick, place the 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. Mix small batches at a time since too much MEKP will result in the hardening of the gelcoat way too fast! Refer to the catalyst chart located on the product page for the gelcoat you are using or follow the label guidelines.
Gel Coat requires the addition of fiberglass resin hardener or catalyst (MEKP) at 1.8% by volume (77ºF) (approximately 12 drops per ounce)
Measure catalyst accurately. Under or over catalyzation retards curing and causes fading and chalking
All Gelcoats from the Bottom Paint Store comes with the MEKP catalyst but additional amounts can be purchased.
Applying Gelcoat by Brush or Roller: Choose a good pure (natural) resin-resistant bristle brush with tapered ends. Avoid brushes that are either too stiff or too soft. For most work, a 3″ or 4″ wide brush will suffice. If there is a trim color, you should have a narrow trim brush on hand. Our Gelcoat comes with MEKP hardener with every purchase, but you may need more which you can purchase as an option depending on the application, temperature, and other environmental factors. Please refer the to Catalyzation chart on the Gelcoat page or on the label. Gelcoat needs to be applied evenly. We suggest a thickness of 18-20 mils to properly cure. The thickness of the matchbook cover is approximately 18 mil. If you’re not sure how thick it is, pick up a mil gauge. This is a simple, easy way to see the thickness of your gelcoat. See this article for more information: How to Apply Gelcoat by Brush and Roller.
Spraying Gelcoat: For best results spraying gelcoat, it is recommended to use a spray gun designed specifically for applying gelcoat and resins, such as the professional grade spray guns offered by FGCI and ES Manufacturing. Next decide if you want to use an aluminum, plastic or paper cup to house the gelcoat. You can use either a heavy-duty, reusable plastic cup or disposable paper cup for spraying gelcoat. There are also disposable cup liners available that you can insert into the plastic Poly-Pro graduated cup or paper cup. You can mix your material right in the lined cup and then simply insert the cast aluminum lid onto the lined cup, attach the cup to the gun and you are ready to spray.
Can I spray gelcoat with an airless sprayer? Yes, you can spray gelcoat with an airless sprayer however it is it is recommended to use a pressure of 3000 psi. The pressure at which you spray gelcoat depends on the type of gun you are using. For example, if you are using a conventional spray gun, you should set the pressure between 30 and 50 psi.
Please follow the instructions located on the products page or the label. Spraying Gelcoat delivery rate of no more than 2.5 pounds per minute with conventional air atomized spray, and no more than 4 pounds per minute with airless equipment. Spray: Airless or Conventional: 2.0-2.5 orifice tip. Use a gelcoat spray gun such as ES Manufacturing Gelcoat Spray Gun G830, ES-G100 Spray Gun, or equivalent.
You will need to thin the gelcoat for it to run through the spray gun. There are 2 thinners that are recommended by the manufacturer when spraying gelcoat: Patch Booster, and Duratec. Patch booster is used with a 5:1 ratio or about 20% by volume. Do not use any other wax additive when using Patch Booster. Duratec is for a cosmetic high gloss finish. It has to be mixed at a 1:1 ratio with gelcoat. Since manufacturer specs change often due to formula updates be sure to follow the most recent recommendations from the technical data sheets. 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.
Initially spray a cover coat as smooth and evenly as you can to cover your repair. This coat should be mostly in the repair area and may be repeated. Sanding between coats is not necessary unless a surfacing agent has been added to your gel coat. Once your repair is covered, feather a ‘flow’ or sanding coat on the masked-off area making layered passes to avoid a buildup of gel coat in any one area. Each of these coats of gelcoat may involve several passes. Be even and consistent in your gun movement, overlapping each previous pass slightly and not hesitating on the ends. When spraying to a radius, flow the gelcoat to the tape. In open flat areas, layer passes. The final thickness should be 16-20 mils minimum or the gelcoat may not fully cure. Gelcoat needs to be applied evenly. We suggest a thickness of 18-20 mils to properly cure. The thickness of the matchbook cover is approximately 18 mils. If you’re not sure how thick it is, pick up a mil gauge. This is a simple, easy way to see the thickness of your gelcoat. As soon as you are done spraying, clean your sprayer fully with acetone. Most re-sprayed gelcoat will cure in 2-4 hours, although overnight cures are ideal.
Finishing your Gelcoat Application: If you’re using our Professional Grade Exterior Gelcoat, you’ll be ready to sand and buff your freshly gelcoated surface once it has cured to a hard surface. You should not be able to dent it with your fingernail. Begin wet sanding with the finest grit that will remove orange peel in the re-sprayed area. This will avoid unnecessary sanding scratches. Usually 320 or 400 grit wet paper is sufficient for the initial sanding. Going up to 400, then 600, and eventually 800 grit sandpaper. Compound and polish with Aquabuff 2000 then happy a wax such as Collinite 925 UV for protection.
Another option is you can use an 800 grit compound for the gelcoat at this stage. You want to use a buffer that turns 1600-3000 RPM. The car polishers won’t work if they’re spinning too slowly, so you want to check the speed of the spin. It’s best to do a 4-foot by 4-foot area at a time. Every 10 feet or so, you’re going to want to clean your pad with a spur or some air to make sure the contaminants don’t scratch your surface. If you want a perfect, glossy shine, use a machine glaze and then two wax coats, and you’ll have a stunning, glossy professional finish.
IMPORTANT GELCOAT APPLICATION TIPS:
DO NOT WORK IN DIRECT SUNLIGHT -Choose a shady location or an overcast day. You should catalyze your material so that it cures as quickly as possible within your working time. Generally, mix one-pint batches. A good practice is to pour the mixed gel coat from the mixing container into another container used for application. This further assures that no uncatalyzed material is clinging to the sides of the pot. “Lay on” the gel coat in a heavy thickness (about 10 mils) using horizontal strokes, and working from top to bottom. Avoid re-brushing as this could remove the waxy surface additive. Remember to always lap wet. Generally, one heavy coat is sufficient. However, if you have opacity problems two coats may be necessary with a light sanding between coats. Once the coating (gelcoat) has cured, it should be block sanded using 250 wet grit paper to remove all brush marks and high spots. Following this, it should be wet sanded with 320, 400, and 600 wet grit paper, buffed, polished and waxed.
Clean repair area and all tools with acetone prior to application
Pot life (amount of time for application of the product) shortens dramatically as you mix larger batch sizes. Keep in mind that you have a limited time to apply what you have mixed (usually between 5-15 minutes).
Measure catalyst accurately. Under- or over-catalyzed gel coat will cure slower and look faded or chalky.
Use the recommended thinners/additives only which are listed on the gelcoat’s product page.
Gel coat will not fully cure without adding a surfacing agent or over spraying with PVA
Check color thoroughly before applying. Gelcoat will not darken or change colors when it dries. The color wet is the color when dry.
Store gel coat in a cool, dry place
Gelcoat should be applied at temperatures of 60ºF to 80ºF
Always use eye and hand protection
Gelcoat should not be applied over paint, wood, metal, or concrete. It usually will not adhere to these surfaces.
Gelcoat will not fully cure without adding a surfacing agent or wax additive sanding aid. You can over-spray with PVA before gel coal reaches its gel stage (5-10 min.), or add 1oz per quart/ 4 oz per gallon of wax additive sanding aid.
Read all warnings on product labels and only use additives recommended as described per each product.
In order to have a form from which to develop your mold, you must either build the article from scratch using wood, plaster, polyester putty, formica, sheet metal, etc. or you must have on hand a completed article which you wish to duplicate. The latter is of course the fastest method. The plug is generally a male model exactly like the item you wish to fabricate in every detail. If the plug does not have draft (taper) then you will have difficulty getting parts off. If the plug has reverse bends, like many canoes, then you will need to make a split mold which can be spread or taken apart.
If the plug contains soft materials on its surface such as plaster, wood, or putty, then it will have to be sealed with lacquer orresinto fill the pores. If plaster is used, it must be oven dried and then sealed.
To prevent your mold from sticking to the plug, the plug must be coated with plastic film known as “PVA.” This is a plastic dissolved in alcohol and has a green color. It can be brushed or sprayed on, but the best system is to spray on three thin coats, the first being a “mist coat.” The appearance will then be green. Each coat must dry half an hour or so and there must be no pools or drips to blemish your mold surface. For the easiest possible parting, before applying the PVA, apply a soft wax (TR Mold Release) formulated for use with PVA.After the third coat ofPVAhas dried, a coating of this wax can be gently applied over it for easy parting.
The Mold
The first step is to apply a gelcoat which will be the mold surface. Thegelcoat must be “exterior gelcoat” (wax free). If many parts are to be taken off the mold, it is desirable to use a“tooling gelcoat” which is designed to give longer life in mold use. The gelcoat should be in contrasting color to the surface of the part you will make. Since most parts are light colored, black gelcoatis commonly used. This facilitates spraying up a uniform thickness of light colored gelcoat since the black will show through thin spots.
If the gelcoat is to be brushed on, two coats must be applied, and the first coat must cure several hours before the second coat is applied. The best means of gelcoat application is a simple gelcoat gundesigned for the purpose and easy to clean. Air pressure of 80 to 90 pounds is desirable. Gelcoat must be applied at least 15 mils thick, or a quart to every 25 square feet of surface. If the plug was rough so that considerable sanding of the gelcoat will be necessary, then double the application. Before applying the gelcoat, it must of course, be catalyzed with MEKp peroxide hardener, using from one to two percent. All gelcoats from the Bottom Paint Store include the MEKp.
When the gelcoat has cured so that it cannot be scratched off with the fingernail at the edge of the mold, which takes from 2 to 4 hours to overnight in cool or humid weather, you are ready for the “skin coat.” This is a layer of ¾ or 1oz. fiberglass mat, thin enough so you can see and remove all air bubbles entrapped by the resin when you “wet-out” the mat. The resinshould be applied with amohair roller or brush until no white fibers remain. Any air bubbles are then eliminated with a grooved plastic or metal laminating roller. The polyester resin used should be “lay-up resin,” which is wax-free. Be careful not to over-catalyze when laying up the glass. Above 75°F one 10-15 cc of hardener to the quart will generally suffice. Below 70°F, 20 cc per quart. Do not work below 65°F.
In laying up a fiberglass mold, warping can be avoided by allowing each layer to “kick” or gel before proceeding with the next layer. For a large mold, it is good to apply just one layer per day. After the “skin coat,” you can use 1½ oz. fiberglass mat for a faster build-up. Generally, woven roving is not used in molds because the pattern transfers through the mold to the gelcoat. If it is necessary to use woven roving fiberglass for strength in a large mold, it is applied after a thickness of 3 or 4 layers of mat has cured hard. The thickness required in a mold depends upon size and shape and the number of parts to be taken off. For a dinghy mold to be used only a few times, four layers of mat might be adequate.
Removing mold from the plug
Allow mold to cure several days if possible so it will hold its shape. The first step is to trim the excess laminate back to the molded edge. This is easily done with a saber saw and a metal-cutting blade. The edges are sanded carefully until the line between the mold and plug is exposed. Then a sharpened “tongue stick” is forced between mold and plug to separate the edges. The stick is then pulled clear around the plug until all edges are free and no bridges remain. Avoid using metal tools for this purpose as they will scratch the mold surface. Then the mold should pull free of the plug. If not, the parts can be flexed or pounded gently with a rubber mallet. If necessary, air or water can be forced under pressure between plug and mold. A hole can be drilled through the interface for this purpose. PVA is water soluble, which facilitates parting with water pressure.
Polishing the mold
Depending upon the condition of the mold surface, it may have to be sanded with 220 grit working up to 600 grit wet or dry. The surface is then compounded with regular and fine finish compound formulated for fiberglass work. Best results can be achieved by using special compounds such as 3M Finesse-It Marine Paste Compound to bring out a mirror finish.
Before using a mold, it should be allowed to cure a week or more if possible. Be sure to use PVA parting film and soft wax for the first 3 or 4 parts, after which a carnauba wax can be used.
Gelcoat problems
Alligatoring, or wrinkling, can result from:
1. Gelcoat too thin in some spots
2. Insufficient hardener, or hardener not mixed will enough.
3. Gelcoat not cured long enough before mat lay-up.
4. Acetone cleaner drips out of roller or brush during mat lay-up.
Original technical article provided by Fiberglass Coatings.
For routine maintenance: Wash regularly with a non-abrasive boat soap and apply a UV-protective marine wax to prevent oxidation and fading.
For light oxidation or dullness: Use a gelcoat cleaner or mild polish to restore shine before sealing with wax.
For heavy oxidation or chalking: Start with a compound, follow with a polish, then protect with a marine-grade wax or sealant.
Bottom line: Regular cleaning and protection prevent major restoration work; neglected gelcoat requires compounding, polishing, and sealing to fully restore appearance.
Tip: Always test compounds and polishes on a small area first, and avoid aggressive abrasives that can permanently thin the gelcoat.
As you haul your boat out of storage you may want to get the gelcoat shining once again. Use the steps below as needed:
New Boats
Which Products To Use: If your boat is new and the finish is still in good condition with little to no oxidation, you can use a one-step clean-and-wax product that combines washing and waxing in one step. We recommend using the 3M Marine Cleaner and Wax.
If your boat has light gelcoat oxidation use the least aggressive method, if possible, to prolong the life of gelcoat. We recommend cleaning with marine boat soap and buffing with the 3M Imperial Compound. Avoid direct sunlight and room temperature is best for application.
Note: An easy way to determine if gelcoat is oxidized is by wiping your hand across the surface. If any chalk wipes off on your hand, the gelcoat is oxidized and you will need to wash and buff the surface before polishing.
Follow these three simple steps to polish your gelcoat:
Step 1: Once you know which polish to use we recommend using a high-quality microfiber towel to apply the product. Avoid low-quality towels because they will shed fibers and leave streaks and residue on the boat.
Step 2: Wet the microfiber rag, remove any excess and apply a tablespoon of polish to the rag. This amount of polish will work for a few square feet. Remember, you want to work in small areas in order to cover the entire surface correctly.
Before buffing, spread the polish evenly across the boat’s gelcoat. You will get the best results when working the polish into the surface with circular motions.
Step 3: Once the polish dries into a haze you can remove it with a clean dry rag. Make sure you get in all the nooks and cracks for a smooth beautiful finish.
Older Boats
If your boat has been in contact with the elements over long periods of time (10-15 years), the process of restoring the appearance of the gelcoat will take some additional steps.
Step 1: Clean the surface. For boats that need a more aggressive cleaning just wash the surface and remove any loose contaminants. You can use a non-abrasive light detergent (marine boat soap) to remove all surface dirt and all previously applied coatings. If you need something stronger to remove surface rust, oil, tar, algae discoloration, black streaks caused from water runoff, exhaust and waterline scum, or other stains we recommend using an acid-based stain remover like Hammerhead Hull Cleaner. It is important to completely remove all stains before waxing, or you’ll seal in the stain.
Step 2: Select your compound. If your boat is a bit more oxidized a rubbing compound (liquid abrasive which “sands” your hull) is needed, but do so carefully as you can run through the gelcoat. The more faded your hull the more compounding you’ll need. The 3M Imperial Compound usually applied with a polisher if possible and compatible 3M pads, like the white 100% wool pad, recommended by 3M. Keep product off bottom paint, if applicable, by taping off as it can spatter. If the compound isn’t strong enough for your level of oxidation and scratches, then you may need to “pretreat” with a 1200 (or 800) grit as needed prior to the compound.
Note: When buffing, you should work on small sections of the hull (3-5ft sections is recommended). It is important to keep the wool pad damp. If you notice the pad is dry and the wool looks ‘matted’ after working the material into one area, just rake the wool back into form with a pad spur and re-wet the pad to continue with the application.
Step 3: Polish the surface. We offer the 3M Finesse-It II or Aqua buff 1000, to help provide a nice finish to the gelcoat after compounding and bring it to a gloss. Apply with the yellow pad by 3M.
Gelcoat is a type of resin that is applied to the hull of a boat in order to give it a smooth, glossy finish. In addition to its aesthetic appeal, gelcoat also helps to protect the hull from UV damage and tough weather conditions. While gelcoat is typically clear, it can also be tinted to a color to give the boat a unique look.
Topcoat is applied above the waterline only and is typically a polyester based high gloss polyurethane that provides long lasting gloss and color retention. Topcoat is available in both clear and colored varieties, and it can also be glossy or matte finish.
Gelcoat Restoration Process (Step-by-Step)
Restoring gelcoat properly requires addressing oxidation in stages, then sealing the surface to protect it from UV damage and water exposure.
Step
Purpose
When Needed
Wash & Decontaminate
Removes dirt, salt, and surface grime
Before any gelcoat work
Compound
Removes heavy oxidation and chalking
Gelcoat appears dull, rough, or faded
Polish
Refines surface and restores gloss
After compounding or for light oxidation
Wax or Seal
Protects against UV, water, and staining
Always after polishing
When to Repair vs Restore Gelcoat
Not all gelcoat issues can be fixed with compounding and polishing. Use the guide below to determine whether restoration or repair is required.
Restore gelcoat if the surface is faded, chalky, lightly scratched, or dull but still intact.
Repair gelcoat if there are deep cracks, chips, blisters, exposed fiberglass, or structural damage.
Re-gelcoating or repainting may be necessary if oxidation returns quickly or the gelcoat has been sanded too thin over time.
Rule of thumb: If the damage can’t be corrected with polishing alone, gelcoat repair products are the safer solution.
Gelcoat Maintenance & Restoration FAQs
How often should gelcoat be waxed?
Most boats benefit from waxing gelcoat every 3–6 months, depending on sun exposure and water conditions.
Can oxidized gelcoat be permanently fixed?
Oxidation can be removed, but regular waxing or sealing is required to prevent it from returning.
Is compounding bad for gelcoat?
Compounding is safe when done sparingly, but excessive compounding can thin the gelcoat over time.
Can gelcoat be restored without a buffer?
Light oxidation can be addressed by hand, but machine polishing is recommended for consistent results.
What causes gelcoat to fade or chalk?
UV exposure, saltwater, pollution, and lack of protective wax are the primary causes of gelcoat deterioration.
