The Basics of Epoxy
Epoxy resin is a chemical wonder that helps to bond one object to another, coat something for protection, create a seal and to perform many other types of repairs. One of the wonderful things about epoxy is that it can bond with a lot of different materials that otherwise would not work with other adhesives. Most adhesives work with only one material at a time but epoxy can be used with everything from fabric to wood to glass, metal and more. Applications are endless. Epoxy was first developed by Paul Schlack in 1934 and since his initial formula, many variations have arisen and today, variations of epoxy are almost endless.
One of the most obvious differentiators for epoxies is whether it cures in a one component system or a two component system. The one component system works by first applying the epoxy, then curing it with a heat source, UV light or some combination of the two. The one step method works by the heat or UV light causing the chemical reaction to harden the epoxy resin. With thermal curing, there is a very specific range of temperatures that will do the job, and one would most likely use a heat gun to do the curing. With UV light, the chemical reaction requires the right amount of light and the right wavelength and this method is used to save energy and work more quickly. This type of epoxy is popular with aerospace, medical, electrical, automotive and other industries, and it is also probably cleaner and easier to work with requiring only one container and no mixing.
Two component epoxies on the other hand, work in a different way. As the name implies, a two component epoxy consists of a resin and a hardener, separately they don’t do much, but when mixed together, a chemical reaction occurs and after a set time, they harden into nigh invulnerability. In a two component system, both parts are usually sold together in a separated syringe-like container that mixes and dispenses as you apply (like 3M epoxy) or in two separate containers of varying sizes depending on mix ratio (like some of the MG Chemicals epoxy). The second type requires various containers for mixing as well as the proper PPE.
In either method, considering the work life of the epoxy is important. If you’re expecting a quick cure time and you’ve picked up something with a longer cure time you probably won’t be happy. Most short work life epoxies will set within three to ten minutes and even then may not be fully cured for 24 hours. Therefore, if you need a really quick repair it’s recommended to use something akin to an epoxy that sets within five minutes. Medium work life epoxies begin to cure within 20 to 40 minutes giving you plenty of time to get everything just right and properly in position. This type is recommended for situations where you need a tight seal and positioning has to be perfect. Long work life epoxy, with up to 100 minutes before curing starts, is best for parts that need to work within more complex systems and in situations where absolute precision is needed. The longer cure time will give you the time you need to get the exact configuration for what you’re doing. When choosing your epoxy, make sure that the job you have to do can be done before curing starts.
Epoxies are a really helpful tool when you’re working on repairs, they can fix an amazing amount of problems, can be made into various shapes if you’re using putties and they dry to a durable finish making them perfect to repair holes, stop leaks and use as a bonding agent. Here at EIO we carry epoxies made by 3M and MG Chemicals, let us know how we can help you get the right epoxy for the job!