Product Instructions

Product Instructions & Application Guides

Learn how to mix, apply, cure, sand, and finish True Composites products for fiberglass repair, marine restoration, mold making, carbon fiber work, and composite fabrication.

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Choose the Product Type You Are Working With

Jump directly to the instructions for fiberglass resin, gelcoat, epoxy repair, pour foam, carbon fiber, mold release, putties, fillers, and safety prep.

Always follow the product label first. Temperature, humidity, surface condition, batch size, and material thickness can affect working time, cure time, adhesion, and final results.

Fiberglass Resin

Mixing, hardener, cloth, mat, and repair layup guides.

Gelcoat

Repair kits, color matching, sanding, buffing, and finishing.

Epoxy resin and structural repair instructions

Epoxy Repair

Mixing, bonding, fairing, fiberglass repair, and surface prep.

Pour Foam

Mixing, expansion planning, flotation foam, trimming, and shaping.

Carbon Fiber

Cloth handling, wet layup, resin selection, trimming, and finishing.

Mold Release

Wax, PVA, mold prep, plug prep, and fiberglass mold making.

Fiberglass putty and fairing compound instructions

Putties & Fillers

Fairing, filling gouges, sanding, shaping, and repair prep.

Safety gear and prep for composite materials

Safety & Prep

Ventilation, PPE, surface prep, and small test batch guidance.

Fiberglass Resin Gelcoat Epoxy Repair Pour Foam Carbon Fiber Mold Release Putties & Fillers Safety FAQ

Fiberglass Resin & Hardener

Fiberglass Resin Instructions

Use these guides for polyester resin, laminating resin, fiberglass repair kits, MEKP hardener, fiberglass cloth, and chopped strand mat.

Polyester Resin Mixing Instructions

Polyester resin must be mixed with the correct amount of MEKP hardener before use. Mix only the amount you can apply within the working time of the batch.

Basic Steps

Prepare the surface by sanding, cleaning, and removing dust, wax, grease, or loose material.
Measure the resin into a clean mixing cup.
Add the recommended amount of MEKP hardener based on the product label instructions.
Mix thoroughly from the bottom and sides of the cup.
Apply immediately using a brush, roller, or spreader.

Do not over catalyze. Too much hardener can create excess heat, cracking, brittleness, poor bonding, or failed repairs.

MEKP Hardener Ratio Guide

MEKP hardener controls the cure of polyester resin and gelcoat. The right amount depends on the product, temperature, batch size, and working conditions.

General Tips

Use the product label as the final authority for the correct ratio.
Warmer temperatures can shorten working time.
Cooler temperatures can slow the cure.
Small batches are easier to control than large batches.
Mix completely before applying to fiberglass cloth, mat, or prepared surfaces.

Fiberglass Cloth Application

Fiberglass cloth is commonly used for clean layups, repairs, reinforcement, and composite fabrication.

Basic Steps

Cut the cloth to size before mixing resin.
Dry fit the cloth over the repair or project area.
Apply mixed resin to the prepared surface.
Lay the cloth into the wet resin.
Wet out the cloth until it turns clear and fully saturated.
Remove trapped air with a roller or brush.

Chopped Strand Mat Application

Chopped strand mat is useful for building thickness, adding bulk, and strengthening fiberglass repairs with polyester resin.

Basic Steps

Tear or cut the mat to fit the repair area.
Apply catalyzed polyester resin to the prepared surface.
Place the mat into the wet resin.
Wet out the mat until fully saturated.
Use a fiberglass roller to remove air bubbles.
Allow the repair to cure before sanding or adding finish layers.

Chopped strand mat is typically used with polyester resin. Confirm compatibility before using it with epoxy systems.

Gelcoat & Finishing

Gelcoat Instructions

Use these guides for marine gelcoat, gelcoat repair kits, pigments, color matching, sanding, buffing, and surface finishing.

Gelcoat Repair Kit Instructions

Gelcoat repair kits are commonly used to fix chips, scratches, gouges, cracks, and small damaged areas on fiberglass surfaces.

Basic Steps

Clean the repair area thoroughly and remove wax, oil, dirt, loose material, and surface contamination.
Sand the damaged area to create a dull surface for better adhesion.
Mix gelcoat and pigment first until the color is close to the surrounding surface.
Add hardener only when you are ready to apply the repair material.
Apply the mixed gelcoat slightly higher than the surrounding surface.
Allow the repair to fully cure before sanding, polishing, or buffing.

Color matching takes patience. Test a small amount first before applying gelcoat to a highly visible repair area.

Gelcoat Mixing & Hardener Instructions

Gelcoat must be mixed thoroughly with the correct amount of hardener before application. Poor mixing can cause soft spots, sticky areas, slow curing, or weak repairs.

Basic Tips

Mix pigment into the gelcoat before adding hardener.
Add hardener according to the product label instructions.
Scrape the bottom and sides of the cup while mixing.
Mix only the amount you can apply within the working time.
Apply gelcoat in a clean, dry, properly prepared repair area.

Do not add extra hardener to force a faster cure. Too much hardener can create heat, cracking, discoloration, brittleness, or poor final results.

Pigment Color Matching Guide

Color matching gelcoat is a gradual process. Start light, add pigment slowly, and compare the color before applying it to the repair.

Color Matching Tips

Start with a small amount of base gelcoat.
Add pigment in very small amounts.
Mix thoroughly before deciding whether more pigment is needed.
Check the color in natural light when possible.
Remember that wet gelcoat may look different than cured gelcoat.
Test a small sample before applying the final repair.

Sanding and Buffing Gelcoat

After gelcoat has fully cured, it can usually be sanded, polished, and buffed to blend the repair into the surrounding surface.

Finishing Steps

Wait until the gelcoat is fully cured before sanding.
Start with the appropriate grit based on the height and condition of the repair.
Progress through finer grits to remove sanding marks.
Use polishing compound to restore shine.
Buff carefully to blend the repair into the surrounding surface.
Clean the area after finishing to remove residue or compound dust.

Avoid aggressive sanding too early. If the gelcoat has not fully cured, sanding can smear the repair or damage the finish.

Epoxy & Structural Repair

Epoxy Repair Instructions

Use these guides for epoxy resin, fiberglass epoxy repair, fairing, filling, bonding, and structural reinforcement.

Epoxy Resin Mixing Instructions

Epoxy systems rely on accurate resin and hardener ratios. Do not guess the ratio. Measure carefully, mix thoroughly, and follow the product label instructions.

Basic Steps

Confirm the correct resin to hardener ratio on the product label.
Measure resin and hardener accurately using clean containers.
Mix slowly and thoroughly to reduce trapped air.
Scrape the sides and bottom of the mixing cup while blending.
Transfer to a second clean cup and mix again when accuracy is critical.
Apply within the listed working time.

Incorrect epoxy ratios can leave the material soft, sticky, brittle, or weak. Epoxy is not the place to freestyle.

Fiberglass Epoxy Repair Guide

Epoxy is often used for strong bonding, fiberglass reinforcement, and structural repairs where high adhesion is important.

Basic Steps

Remove damaged, loose, cracked, or contaminated material.
Sand or grind the repair area back to a solid surface.
Clean the area thoroughly before applying epoxy.
Pre-cut fiberglass cloth or reinforcement before mixing epoxy.
Apply mixed epoxy to the prepared repair area.
Lay fiberglass into the wet epoxy and fully wet out the material.
Remove trapped air and allow the repair to cure fully before sanding.

Fairing Compound Application

Fairing compounds help smooth uneven surfaces, fill low spots, and prepare composite repairs for primer, paint, gelcoat, or final finishing.

Basic Steps

Sand the surface to create a dull, mechanical bond area.
Remove dust, grease, wax, oil, and loose material.
Mix the fairing compound according to the product instructions.
Apply with a spreader, putty knife, or fairing board.
Build the material slightly above the final surface level.
Allow to cure completely before sanding smooth.

Do not apply fairing compound over glossy, dirty, oily, or waxed surfaces. The bond will be weaker, and the repair may fail later.

Surface Prep Before Epoxy

Epoxy needs a clean, dull, dry, and properly prepared surface. Surface prep is not optional. It is the entire ballgame.

Prep Checklist

Remove loose or damaged material.
Sand glossy surfaces until dull.
Vacuum or wipe away sanding dust.
Remove wax, grease, oil, moisture, and contamination.
Make sure the surface is dry before applying epoxy.
Confirm product compatibility before applying additional coatings over epoxy.

Marine Pour Foam

2 Part Pour Foam Instructions

Use these guides for pour foam, flotation foam, marine foam, expanding foam, cavity filling, trimming, and shaping.

2 Part Pour Foam Mixing Instructions

2 part pour foam expands quickly after mixing, so the work area needs to be fully prepared before Part A and Part B are combined.

Basic Steps

Make sure the area is clean, dry, and ready before mixing.
Measure Part A and Part B according to the product label instructions.
Use clean mixing containers and tools.
Mix quickly and thoroughly.
Pour immediately into the prepared cavity or form.
Allow room for expansion.
Let the foam fully cure before trimming, shaping, sealing, or covering.

Pour foam moves fast. Do not mix until the area is ready, the path is clear, and your brain has officially clocked in.

Foam Expansion & Pour Planning

Pour foam expands as it cures. Planning the pour helps prevent overfilling, pressure buildup, uneven expansion, and wasted material.

Planning Tips

Review the product expansion information before starting.
Estimate the cavity volume before mixing material.
Use smaller pours when filling larger spaces.
Allow each pour to expand before adding more material.
Do not completely fill a closed cavity with liquid foam before expansion.
Give expanding foam room to rise safely.

Avoid trapping expanding foam in a sealed space with nowhere to go. Expansion pressure can damage surrounding surfaces.

Marine Flotation Foam Guide

Marine flotation foam is commonly used in boats, flotation cavities, restoration projects, void filling, and lightweight support areas.

Best Practices

Remove wet, damaged, rotten, or contaminated old foam when necessary.
Confirm the area is dry before pouring new foam.
Pour in stages for better control.
Allow foam to expand and cure before adding additional pours.
Trim excess foam after cure.
Seal or cover the foam according to the project requirements.

Foam Trimming and Shaping

After curing, pour foam can usually be trimmed, cut, sanded, or shaped to fit the project area.

Finishing Tips

Wait until the foam is fully cured before trimming.
Use a knife, saw, rasp, or sanding tool depending on the project.
Shape gradually instead of removing too much material at once.
Wear eye protection and respiratory protection when sanding foam.
Remove dust before applying fiberglass, resin, coatings, or coverings.

Do not sand cured foam without proper protection. Foam dust is not confetti. Your lungs did not RSVP.

Carbon Fiber

Carbon Fiber Instructions

Use these guides for carbon fiber cloth, wet layups, resin wet out, trimming, finishing, and composite fabrication projects.

Carbon Fiber Cloth Application

Carbon fiber cloth should be handled carefully before layup to avoid fraying, distortion, contamination, or shifting the weave pattern.

Basic Steps

Cut the carbon fiber cloth carefully using sharp scissors or shears.
Dry fit the fabric before mixing resin.
Prepare the surface according to the resin system instructions.
Apply resin evenly to the surface.
Place the carbon fiber cloth into the wet resin.
Wet out the cloth carefully without dragging or distorting the weave.
Remove trapped air and allow the layup to cure fully.

Carbon fiber can fray easily. Cut and handle it carefully before layup so the final part looks clean and professional.

Carbon Fiber Wet Layup Instructions

Wet layup is a common carbon fiber process where resin is applied directly to the fabric during the layup process.

Layup Tips

Prepare all fabric pieces before mixing resin.
Use a resin system compatible with carbon fiber.
Apply resin evenly to the work surface or mold.
Place the carbon fiber into position carefully.
Wet out the fabric until fully saturated.
Remove air pockets with a roller, brush, or squeegee.
Allow the laminate to cure completely before trimming or finishing.

Resin Selection for Carbon Fiber

Carbon fiber performance depends heavily on the resin system, surface preparation, working time, and curing conditions.

Selection Tips

Confirm resin compatibility with carbon fiber cloth.
Choose the resin system based on the project type.
Use the appropriate resin for cosmetic, structural, or repair applications.
Check the working time before starting the layup.
Follow the resin system instructions for cure time.
Confirm whether post cure is required for the specific application.

Do not assume every resin is right for carbon fiber. Compatibility matters, especially for structural or performance parts.

Carbon Fiber Trimming and Finishing

Once cured, carbon fiber can be trimmed, sanded, coated, polished, or finished depending on the final application.

Finishing Tips

Wait until the laminate is fully cured before trimming.
Wear eye protection, gloves, and respiratory protection when cutting or sanding.
Use sharp tools for cleaner edges.
Sand carefully to avoid damaging the visible weave.
Remove dust before applying coatings or clear finishes.
Use a compatible finish or clear coat when needed.

Carbon fiber dust is not something to mess with. Use proper protection when cutting, drilling, or sanding cured carbon fiber.

Mold Making & Release

Mold Release Instructions

Use these guides for mold release wax, PVA, mold preparation, plug prep, release systems, and basic fiberglass mold making.

Mold Release Wax Instructions

Mold release wax helps create a barrier between the mold surface and the part being made. Proper application is critical for clean part removal.

Basic Steps

Clean the mold or plug surface completely before applying wax.
Apply a thin, even coat of mold release wax with a soft cloth or applicator.
Allow the wax to haze according to the product instructions.
Buff the surface clean with a soft cloth.
Apply multiple coats when working with new molds, repaired molds, or difficult release surfaces.
Allow proper time between coats before applying resin, gelcoat, or laminate.

Do not rush mold release wax. Thin, even coats beat one heavy coat every time. This is mold prep, not cake frosting.

PVA Mold Release Instructions

PVA mold release can be used as an additional barrier over properly prepared and waxed surfaces.

Basic Steps

Make sure the waxed surface is clean, smooth, and ready.
Apply PVA in a thin, even film using the recommended method for the product.
Avoid heavy runs, puddles, streaks, or uneven buildup.
Allow PVA to fully dry before applying gelcoat, resin, or laminate.
After part removal, wash or remove PVA residue from the finished part as needed.

Do not laminate over wet PVA. Let it dry fully before starting the next step.

Preparing a Mold Surface

A mold surface should be clean, smooth, polished when needed, and properly released before production begins.

Prep Checklist

Inspect the mold or plug surface for scratches, dull areas, wax buildup, or contamination.
Clean the surface thoroughly before applying any release product.
Polish the surface if needed before wax or PVA application.
Apply mold release wax according to the product instructions.
Use PVA when an additional release barrier is needed.
Confirm the surface is dry and ready before applying gelcoat, resin, or laminate.

Basic Fiberglass Mold Making Guide

Fiberglass mold making requires careful plug preparation, proper release application, gelcoat, reinforcement, and full cure time.

Basic Process

Prepare and polish the plug surface.
Apply the correct release system before building the mold.
Apply tooling gelcoat if required for the project.
Build laminate thickness with fiberglass and resin.
Allow the mold to fully cure before separating it from the plug.
Trim, sand, polish, and prepare the mold before production use.

The mold is only as good as the surface it is built from. Bad plug prep creates bad molds. Bad molds create bad parts.

Putties, Fillers & Fairing

Putties & Fillers Instructions

Use these guides for marine putties, fairing compounds, gap filling, bonding, surface repair, sanding, shaping, and prep work.

Fiberglass Putty Instructions

Fiberglass putty is commonly used for filling gouges, rebuilding damaged areas, bonding parts, shaping repairs, and adding strength where standard filler is not enough.

Basic Steps

Remove loose, cracked, weak, or contaminated material from the repair area.
Sand or grind the surface to create a rough mechanical bond area.
Clean away dust, wax, oil, grease, moisture, and debris.
Mix the putty according to the product label instructions.
Apply firmly into the damaged area using a spreader or putty knife.
Shape slightly above the final surface level to allow for sanding.
Allow the material to fully cure before sanding, drilling, coating, or finishing.

Do not apply putty over glossy, dirty, oily, wet, or waxed surfaces. If the surface prep is lazy, the bond will be lazy too.

Marine Fairing Compound Guide

Marine fairing compound is used to smooth uneven surfaces, fill low spots, shape contours, and prepare fiberglass or composite surfaces for primer, paint, gelcoat, or final finishing.

Basic Steps

Sand the surface until it is dull and ready for bonding.
Remove dust and contamination before applying fairing material.
Mix the fairing compound thoroughly according to the product instructions.
Apply with a spreader, putty knife, or fairing board.
Feather the edges into the surrounding surface.
Build the material slightly higher than the final surface.
Allow the material to cure completely before sanding smooth.

Fairing is for smoothing and shaping, not for replacing proper structural repair. If the area needs strength, reinforce it first.

Filling Gouges, Voids, and Cracks

Gouges, voids, chips, and cracks should be cleaned, opened up when needed, and filled with the correct repair material for the depth and purpose of the repair.

Repair Tips

Inspect the damage to determine whether it is cosmetic or structural.
Remove loose or broken edges before filling.
Open narrow cracks slightly so repair material can bond properly.
Sand the surrounding surface to create a bonding area.
Use the correct putty, filler, fairing compound, resin, or reinforcement for the repair.
Fill slightly above the surface level.
Sand smooth after full cure.

Sanding and Surface Prep

Proper sanding and surface preparation help putties, fillers, fairing compounds, primers, gelcoat, resin, and coatings bond correctly.

Prep Checklist

Remove weak, loose, peeling, or contaminated material.
Sand glossy surfaces until dull.
Feather the surrounding area for smoother blending.
Vacuum or wipe away sanding dust.
Remove wax, oil, grease, silicone, and moisture before applying repair material.
Confirm the surface is dry before starting the repair.

Surface prep is where repairs are won or lost. The product can be great, but it cannot save a dirty surface. Harsh, but fair.

Safety & Prep

Before You Start

Composite materials can deliver professional results, but they need to be handled correctly. Use proper protection, work in the right environment, and review product labels before mixing or applying materials.

Work in a Ventilated Area

Use resins, hardeners, solvents, gelcoat, mold release products, and repair materials in a clean, dry, well-ventilated area. Avoid enclosed spaces without proper airflow.

Wear Proper Protection

Wear gloves, eye protection, and appropriate respiratory protection when mixing, applying, sanding, cutting, spraying, or grinding composite materials.

Prepare the Surface Correctly

Most repairs require a clean, dry, dull, sanded surface. Remove dust, wax, oil, grease, moisture, loose material, and contamination before applying resin, gelcoat, epoxy, putty, or filler.

Mix Small Test Batches

When working with a new product, unfamiliar temperature, or important repair, mix a small test batch first. This helps confirm working time, cure behavior, and application feel before committing to the full project.

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Common Questions

Product Instruction FAQs

How do I know which instructions apply to my product?

Start with the product label first, then use the guide that matches the material type you are using. For example, gelcoat repair kits should follow gelcoat instructions, while fiberglass cloth repairs should follow resin and fiberglass layup instructions.

Do temperature and humidity affect cure time?

Yes. Cooler temperatures can slow curing, while warmer temperatures can shorten working time. Humidity, batch size, material thickness, and airflow can also affect how a product handles and cures.

Can I use more hardener to make resin or gelcoat cure faster?

Only use hardener within the recommended range listed on the product label. Too much hardener can cause excess heat, cracking, brittleness, discoloration, weak bonding, or failed repairs.

Do I need to sand before applying resin, gelcoat, epoxy, putty, or filler?

Usually, yes. Most composite repair products need a clean, dry, dull, sanded surface for proper adhesion. Glossy, oily, waxed, dusty, or wet surfaces can lead to weak bonding and repair failure.

Can I apply gelcoat over epoxy?

This depends on the specific products, cure stage, surface preparation, and compatibility. When in doubt, contact support before applying gelcoat over an epoxy repair.

What should I do if my product does not cure?

Check the mix ratio, temperature, hardener amount, batch size, product age, and surface contamination. Soft or sticky material usually points to incorrect ratio, low temperature, poor mixing, or contamination.

Should I mix a test batch first?

Yes, especially when using a product for the first time or working in unfamiliar temperatures. A small test batch helps confirm working time, cure behavior, and application feel before starting the full project.

What safety gear should I use?

Wear gloves, eye protection, and appropriate respiratory protection when mixing, applying, sanding, cutting, spraying, or grinding composite materials. Work in a clean, dry, well-ventilated area and review the product label before use.

Need Help Choosing?

Find the Right Product Before You Start Your Project

Every repair, layup, mold, and restoration project is a little different. If you are unsure which product or process is right for your application, contact True Composites before you start.

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