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The epoxy mixture has not cured after the recommended cure time has passed
possible causes and solutions
Off ratio—too much or too little hardener will affect the cure time and thoroughness of the cure.
- Remove epoxy. Do not apply additional material over non-curing epoxy. See Removing epoxy.
- Check correct number of pump strokes—use equal strokes of resin and hardener. DO NOT add extra hardener for faster cure!
- Check for correct pump (5:1 or 3:1 ratio).
- Check pump metering ratio (see pump instructions). See Dispensing.
- Allow extra curing time in cool weather.
- Apply heat to maintain the chemical reaction and speed the cure. Raise the temperature above the hardener’s minimum recommended cure temperature. (NOTE! Unvented kerosene or propane heaters can inhibit the cure of epoxy and contaminate epoxy surfaces.)
- Use a faster hardener, designed to cure at lower temperatures. See Controlling Cure Time.
- Remove epoxy. Do not apply additional material over non-curing epoxy. See Removing Epoxy.
- Mix resin and hardener together thoroughly to avoid resin rich and hardener rich areas.
- Add fillers or additives after resin and hardener have been thoroughly mixed. See Mixing.
- Remove epoxy. Do not apply additional material over non-curing epoxy. See Removing epoxy.
- Check for proper resin and hardener. Resin will not cure properly with other brands of hardener or with polyester catalysts.
Bond Failure
possible causes and solutions
Wet out bonding surfaces before applying thickened epoxy. Re-wet very porous surfaces and end grain. See Two-step Bonding.
Increase bonding area by adding fillets, bonded fasteners or scarf joints.
Use just enough clamping pressure to squeeze a small amount of epoxy from the joint. See Clamping.
Clear coating turned cloudy
possible causes and solutions
- Apply moderate heat to partially cured coating to remove moisture and complete cure. See out-gassing caution.
- Use 207 Special Coating Hardener for clear coating applications and for bonding thin veneers where epoxy may bleed through to the surface.
- Apply coating at warmer temperature—epoxy is thinner at warmer temperatures.
- Apply epoxy in thin coats.
- Apply moderate heat to release trapped air and complete cure. See Caution.
Waxy film appears on surface of cured epoxy
possible causes and solutions
- Blush is water soluble. Remove with water. See Special preparation—Cured Epoxy.
- Use 207 Special Coating Hardener. 207 Hardener is blush free.
Runs or sags in coating
possible causes and solutions
- Use 800 Roller Covers and roll the coating out into a thinner film. A thin film will flow out much smoother than a thicker film after it is tipped off with the foam roller brush.
- Warm the epoxy to thin it or apply the coating at a warmer temperature. See Barrier Coating.
- Apply the coating at a warmer temperature.
- Warm the resin and hardener before mixing to speed the cure in cool weather.
- Switch to a faster hardener if possible. See Controlling Cure Time.
Fairing Compound (epoxy/407 or 410 mixture) sags and is difficult to sand
possible causes and solutions
Thick fairing compound (epoxy/407 or 410 mixture) sags
possible causes and solutions
Allow the wet-out coat to gel before applying the fairing material to vertical surfaces. See Fairing.
Paint, varnish or gelcoat will not set up over epoxy
possible causes and solutions
Allow the final epoxy coat to cure thoroughly. Allow several days if necessary for slow hardeners at cooler temperatures. Apply moderate heat to complete the cure if necessary. See Controlling Cure Time.
- Use a different type of paint. Some paints and varnishes may be incompatible with some hardeners. If unsure, test for compatibility on a coated piece of scrap material.
- Use 207 Hardener. It is compatible with most paints and varnishes.
Remove the amine blush and sand the surface thoroughly before applying paints or varnishes. See Final Surface Preparation.
Epoxy became very hot and cured too quickly
possible causes and solutions
- Mix smaller batches.
- Transfer the mixture to a container with more surface area,such as a paint roller tray, immediately after mixing. See Controlling Cure Time, Dispensing and Mixing.
Use 206 Slow or 209 Extra Slow Hardener in very warm weather.
Bubbles formed in coating over porous material (bare wood or foam)
possible causes and solutions
- Coat the wood as its temperature is dropping—after warming the wood with heaters or during the later part of the day.
- Apply a thinner coat, allowing air to escape easier.
- Tip off the coating with a roller cover brush to break bubbles. See Caution.
Pinholes appear in epoxy coating over abraded fiberglass or epoxy
possible causes and solutions
After applying epoxy with an 800 Roller Cover, force epoxy into pinholes with a stiff plastic or metal spreader held at a low or nearly flat angle. Re-coat and tip off coating after all pinholes are filled.
Fish-eyeing in coating
possible causes and solutions
- Be sure mixing equipment is clean. Avoid waxed mixing containers.
- Be sure surface is properly prepared. Use proper grit sandpaper for the type of coating you are applying. (See coating manufacturer’s instructions for proper surface preparation.) After surface is prepared, avoid contamination—fingerprints, exhaust fumes, rags with fabric softener (silicone). Coat within hours of preparation. After wet sanding, rinse water should sheet without beading (beading indicates contamination). Wipe with appropriate solvent and re-rinse until rinse water no longer beads.
Hardener has turned red after several years storage
possible causes and solutions
