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Working with Epoxy

Careful measuring of epoxy resin and hardener, and thorough mixing are essential for a proper cure.  Whether the resin/hardener mixture is applied as a coating, or modified with fillers or additives, observing the following procedures will assure a controlled and thorough chemical transition to a high-strength epoxy solid.

1. Dispense the correct proportions of resin and hardener into a clean plastic, metal or wax-free paper container.  Don't use glass or foam containers because of the potential danger from exothermic heat build-up. 

DO NOT attempt to adjust the epoxy cure time by altering the mix ratio.  An accurate ratio is essential for a proper cure and full development of physical properties.

2. Stir the two ingredients together thoroughly with a wooden mixing stick.  Stir  the mixture for at least 2 full minutes to ensure the hardener is dispersed through the resin. (longer for larger batches)  Scrape the sides and the bottom of the pot as you mix.  Use the flat end of the mixing stick to reach the inside corner of the pot.

3. By adding different powder modifiers to the resin/hardener mixture, you can convert a liquid system to either an adhesive, filleting or fairing compound.   You must mix the resin and hardener thoroughly, prior to adding the fillers, and then  mix again to thoroughly disperse the powder. 

The mixture will seem to thicken almost immediately, but will become considerably thinner with more stirring.  Continue adding small amounts of filler until the proper consistency is reached.

 

Removing amine blush

Amine blush is a by-product of the epoxy curing process that forms as a wax-like film on epoxy surfaces during final cure phase.  The blush is water soluble and can easily be removed, but can clog sandpaper and inhibit subsequent bonding if not removed.  Wash the surface with clean water and an abrasive pad, such as a Scotchbrite pad.  Dry the surface with plain white paper towels to remove dissolved blush before it dries on the surface.  After washing with the abrasive pad, the surface should appear dull.  Sand any remaining glossy areas with 80 grit sandpaper.

 

Clean up

Contain large spills with sand, clay or other inert absorbent material.  Use a small scraper to contain small spills and collect as much material as possible.  Follow up with absorbent towels.

Clean resin, or mixed epoxy residue with acetone.  Follow all safety warnings on solvent containers.  Clean hardener residue with warm soapy water.

Do not dispose of resin or hardener in a liquid state.  Waste resin and hardener can be mixed and cured, in small quantities, to a non-hazardous inert solid.

 

Epoxy Safety Tips

Epoxies are relatively benign chemicals.  The risk of exposure to resin, hardener and mixed epoxy is greatest when they are liquid and as epoxy cures, the chemical ingredients react to form a non-hazardous solid.  As it solidifies, epoxy and its components are less likely to enter the body.

Skin contact is the most common means of exposure to resins and hardeners.   Exposure by inhaling vapors is unlikely because epoxy evaporates slowly, however, the risk increases when ventilation is inadequate or when the products are heated.  Sanding partially cured epoxy produces airborne dust, which increases your risk to exposure by skin contact, inhaling or ingesting.  Do not overlook or underestimate this hazard.

 

ATL encourages the following safety recommendations :

1. Avoid direct skin contact with resin, hardener and mixed epoxy by wearing protective clothing.  Wear plastic gloves whenever you handle epoxy products.  From experience, it is also more comfortable to wear a pair of cotton gloves under the plastic gloves to keep your hands dry.

Barrier skin creams provide additional protection.  Use a waterless skin cleanser to remove  uncured epoxy from the skin.  Never use solvents to remove epoxy from you skin.  845 Skin Cleaner is available from ATL.

2. Protect your eyes from contact with resin, hardeners, mixed epoxy and solvents by wearing safety glasses.  If contact should occur, immediately flush the eyes with liberal quantities of water under low pressure for 15 minutes.  If discomfort persists, seek medical attention.

3. Avoid inhalation of vapours.  Use epoxy only in areas with good ventilation.  In close quarters, such as boat interiors, be especially careful to exhaust the space and provide a supply of fresh air.  Wear a dust mask when you sand epoxy, taking extra care if it has cured for less than a week.

4. Stop using the product if you develop a skin rash.  Resume work when the rash disappears, usually after three or four days.  When you go back to work, improve your safety precautions and prevent any skin contact whatsoever, as well as exposure to vapours.  If problems persist, consult a doctor.

For additional Safety Information,  please contact ATL Composites