How Epoxies Work
Epoxy coatings are thermosetting polymers. When you buy them, they consist of two parts: an epoxy resin and a hardener. After equal parts of the epoxy resin and hardener are thoroughly catalyzed, a really hard finish, that resists scratches, water, chemicals and solvents, is produced.
The keys to achieving a coating, that is thoroughly catalyzed, are good surface preparation, an acceptable working environment and, above all, mixing the ingredients according to the instructions. If you control your process, you will control your outcome. Of course, that’s slightly easier said than done.
When you mix the epoxy resin and a hardener together, an exothermic chemical reaction begins. Exothemic means that the chemical reaction generates heat. In this chemical process the mixture undergoes a transformation as it cures from liquid to gel to solid.
Curing takes time. How much time depends on several factors. These include the type of hardener used, the ambient temperature, the temperature of the substrate and the amount of heat generated in the exothermic reaction. As you can guess, a major factor is heat. The warmer the epoxy is, the faster it cures.
Safely Working with Epoxy Resin
Prior to working with epoxies, carefully read the manufacturer’s Safety Data Sheet (SDS) and the safety precautions in their technical bulletins. The major health risk in working with these materials is skin irritation. Repeated contact can result in your body becoming sensitized, which can cause rashes and dermatitis.
Always wear disposable gloves when handling epoxy resins and hardeners. If you get any of the epoxy mixture on your skin, never wash it off with a solvent, such as lacquer thinner. It is one of the worst possible things that you could do. The solvent will drive the harmful chemicals into your body. Instead, you should wash any of the solvent from your skin with soap and water. Then moisturize you skin with a lotion. If a bad rash appears, consult your doctor.
Potentially, after the two components are mixed together, you could burn yourself. Combining the resin and hardener initiates a chemical reaction that generates heat and creates toxic fumes. Large amounts of the mixtures require safe handling. High heat can melt Styrofoam containers and shatter glass jars. Instead use polyester plastic cups for mixing, work in a well-ventilated area and avoid breathing fumes.
To learn more about the health risks associated with working with epoxy resin, read Safety Tips for Epoxy Resin Systems.