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.
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 under-estimate 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