Category Archives: Fiberglass Repair

Hawk Epoxy System

How do I choose Hawk Epoxy Catalyst and Fillers?

R1 Epoxy Resin – a smooth, low-viscosity liquid epoxy resin. With a variety of Hawk Epoxy Catalysts, it can be cured under a wide range of temperatures and environmental conditions to form a high strength plastic with superior moisture barrier characteristics. Hawk Epoxy is available in four system sizes color coded on each label. Note: Mix ratios vary by catalyst. For optimal product utilization, be sure to choose the same Size for both the resin and catalyst. I.e Size 1 Resin with Size 1 Catalyst.

ChooseCatalyst

C1 ULTRA SLOW CURE CATALYST: Designed for use with HAWK EPOXY R1 Resin for construction and repairs with superior adhesion, strength, bonding, filling, and moisture barrier qualities at higher temperatures and for an ultra slow cure. Do not use under Sea Hawk marine wood varnish.

C2 SLOW CURE CATALYST: Designed for use with HAWK EPOXY R1 Resin for construction and repairs with superior adhesion, strength, bonding, filling, and moisture barrier qualities at higher temperatures and for a slow cure. Do not use under Sea Hawk marine wood varnish.

C3 FAST CURE CATALYST: Designed for use with HAWK EPOXY R1 Resin for construction and repairs with superior adhesion, strength, bonding, filling, and moisture barrier qualities at cooler temperatures and for a fast cure. Do not use under Sea Hawk marine wood varnish.

C5 CLEAR FINISH CATALYST: Designed  for use with HAWK EPOXY R1 Resin for very clear fiberglass cloth and coating applications with exceptional moisture barrier characteristics. Perfect for natural wood and carbon fiber clear coats with no blush. Longer working times in very warm temperatures. May be used under Sea Hawk marine wood varnish.

TIP* For easy accurate measuring be sure to use the Hawk Epoxy Pumps that are calibrated to dispense the correct amount of resin and catalyst. This is much easier and leave little room for mistakes.

Next choose the best Hawk Epoxy Filler depending on the application:


Choose Hawk Epoxy FIller

F1 High Load Adhesive Fiber Filler – Thickens to a light grey color creating an easy to use adhesive designed for bonding hardware and other applications with dissimilar materials. This mixture will maximize bond strength for anticipated high loads.

F2 Structural Adhesive Filler – Thickens to an off white color, creating a general purpose thickening additive for bonding, gap filling and filleting. Mix to a workable consistency allowing sag-free and easy flow properties for vertical and overhead applications.

F-3 Light Density Adhesive Micro Fiber Filler – 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.

F4 Bridging Adhesive Filler – Thickens to a brown color, creating an easy to use adhesive with excellent gap filling and filleting qualities. This mixture blends with many different types of wood to allow for a natural looking fillet or gap fill.

F5 Light Density Fairing Filler – Thickens to a reddish brown color, achieving an easy to sand and carve fairing compound while still remaining strong and light weight.

F6 MicroSphere Fairing Filler – Thickens to a white color, creating a lightweight fairing compound for small to large areas. This product holds a feathered edge very well and is suitable for nearly every substrate. This closed celled structure can also be used for increased acoustic and thermal insulation.

For the easiest was to choose your system, view our Hawk Epoxy Size 1 Kit

Boat Blister Repair

Just because a blister or two develops on your boat it is not a serious issue and only a small number of boats develop a big problem with blisters.

Needed materials: Acetone, sanding block, Hawk Filler, acid safe disposable brushes

HawkFillerQuartCansMake sure blisters are drained and grind blister deep enough to remove damaged material beneath the gelcoat. Increase area as needed until all laminate around is sound. Clean area and allow to dry.

Hawk Filler goes on like putty to fill, patch, seal or rebuild aluminum, wood, concrete, fiberglass and steel. Hawk Filler can be drilled, tapped, or machined.

Mixing
Mix on a non-porous surface. Do not mix on cardboard, paper-based and/or porous surface. Wear tight-fitting rubber gloves. Using equal parts of Part A and Part B, mix thoroughly to even uniform color. Mix using a putty knife, trowel or spatula. Apply immediately after mixing.

Application
Apply using a putty knife, spatula or trowel. Spread smoothly on the surface in a 1/8″ – 1/4″ layer using heavy hand pressure to displace air bubbles/voids. If applying multiple coats, begin spreading away from the previously applied film so as not to trap air bubbles or leave an uncoated surface area. When using as a patch or grout, force material into hole or joint and smooth to the thickness needed.

CLEAN-UP
Wear chemical resistant gloves. Mix leftover Part A and Part B, allow curing before disposing. Scrape up spilled material with a putty knife or cover material with an absorbent material and sweep into a container for disposal. For product already mixed, use acetone.

After repairs paint with Sea Hawk bottom paint or if redoing the hull apply Tuff Stuff primer, followed by bottom paint.

If the blister has damaged the fiberglass that will need to be repaired with fiberglass cloth cut to match damaged area.

Which Resin Should I Choose?

Choosing the right resin depends on the type of project you are tackling. Listed below are the most common types of resins are their intended uses:

General Purpose Repair Epoxy Resin Kit

Hawk Epoxy KitEvery household should own a Hawk Epoxy Kit like this. You can use it to repair anything around your home or own your boat. This kit comes with the resin, catalyst and your choice of filler. Just mix them together and you have an excellent bonding, filling, or adhesive paste.

Polyester Resin:

MARINE ResinPolyester resins are unsaturated resins that are combined with hardeners, such as MEKP.

Polyester resin is used more for fiberglass lay-up or if you’re going to finish a repair with gelcoat, as the polyester resin will bond to the gelcoat better than epoxy.

Vinyl Ester Resin:

Vinyl ester resins are formulated with a base of polyester resin strengthened with epoxy molecules (a hybrid form of polyester and epoxy) and also use peroxides, such as MEKP, for hardening. These are cheaper than epoxy resins and more expensive than polyester.

Vinyl esters are more tolerant of stretching, less likely to show stress cracking and more resistant to water penetration. Vinyl ester is the choice when improved resistance to moisture is the goal (like repairing a blistered hull).

Long term water exposure (hull or water tank) or if impact resistance is important vinyl ester is usually chosen.

Epoxy Resin:

Epoxy ResinEpoxy resins are cured with the addition of a hardener. Unlike the polyester and vinyl ester resins, cured with a small amount of catalyst, epoxy resins usually require a lot more, often 1:1 or 2:1. A epoxy resin is the most expensive of these.

Epoxy resin has the best bonding strength as it will bond dissimilar or already cured materials for strong, reliable repair work. This is the most expensive resin but offers the most in its ability to flex, prevent delamination and ease of repair work.

If doing a repair and not overlaying with gelcoat then the epoxy will perform best as it tends to act as a stronger “glue” for the patch to the surrounding surface.

 Klear Kote Epoxy Resin (Bar Top Epoxy Resin):

A Premium Commercial Grade Clear Epoxy Resin – Klear Kote Epoxy Resin is used extensively in coating surfaces and in table tops where a clear, hard and durable coating is required. Commonly seen on bar tops and restaurant tables. Easy to use 1:1 mixing ratio of resin and hardener.  Items coated with it will become permanently preserved and protected for your enjoyment throughout a lifetime. The epoxy resin will not exhibit blushing or sweat out under high humidity conditions.

How to use a Fiberglass Repair Kit

A hole in your fiberglass looks bad and can lead to water damage but it can be repaired Fiberglass Repair Kitwith patience. Fiberglass is a strong material that will bond to almost any surface if prepared. It is applied by cutting the mat into the size of the repair and layering. The resin, mixed with hardener, is applied to the mat. See our 1 Quart fiberglass repair kit.

Most professionals recommend exposing the sound fiberglass around the damaged area to have a firm base. Grind down the edges to firm fiberglass and then clean the damaged area with acetone, or solvent provided, to remove any dust or grease that may remain. If repairing from the inside, place tape over the outside of the hole or crack to prevent resin from running down the finished face.

Cut the fiberglass into layers for size of repair. Mix the resin and hardener as directed, in small amounts as it will harden quickly. Layer the fiberglass and resin until level with the surrounding area, completing with the cloth overlapping well onto the sound hull surface.

After cured remove irregularities in the patch surface with a disc sander or drill with sanding attachment…don’t over sand, just smooth. Move to finer paper until it matches the contour. If using gelcoat to finish off patch see our gelcoat application guide or gelcoat repair guide.

Click here for the West System Handy Repair Pack or Maxi Repair Pack guide to application.

How to Make a Fiberglass Mold

Making a Fiberglass Mold

The Plug

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 or resin to 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 of PVA has 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. The gelcoat must be “exterior gelcoat” (wax free). If many parts are to be taken off the mold, it is desirable to use a “tooling gelcoatwhich 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 gelcoat is

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 gun designed 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 resin should be applied with a mohair 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.