The term “epoxy” gets slung around as if there were only 1 type of epoxy used in every situation. But contrary to the popular misconception, “epoxy” actually comes in a wide variety of hardeners and resins. And here they are:
The resins used in epoxy don’t offer variety that the hardeners offer. There are 3 types of resins:
- Bisphenol A Resin – This resin has a lot of viscosity, a moderate amount of flexibility, and a moderate amount of chemical resistance.
- Bisphenol F Resin – This resin is similar to the “Bisphenol A” variety, except its flexibility is on the lower end of the spectrum.
- Phenolic Novolac Resin – This resin offers a high amount of viscosity, but because it’s a novolac, it will become very hard, which means there is no room for flexibility. Additionally, it is very chemical resistant.
Depending on what type of application the flooring or painting installer is searching for, they have a variety of epoxy options to choose from. And a part of that reason is because of these (3) different types of epoxy resin.
Now, although there are 3 different resins to choose from, the epoxy hardeners have the largest range of selection, by offering up to 6 different hardeners. Each of these hardeners has different sets of properties that they can offer, making the epoxy line-up a smorgasbord of commercial coating options.
- Polyamide Hardeners – Polyamide hardeners are one of the most versatile epoxies. Out of the epoxy hardeners, they offer the best flexibility, the best adhesion, the best resistance to potable water, the best color and blush stability, and the best corrosion resistance. One of our most commonly used polyamide epoxies is Sherwin Williams’ Macro-Poxy 646. Conversely, although suitable for many applications, the polyamide epoxy falls short in chemical resistant against solvents and acids, and doesn’t offer a lot of viscosity.
- Amidoamine Hardeners – These hardeners typically fall behind the polyamide hardeners. The offer better than average flexibility, adhesion, viscosity, and color stability. However, one noticeable area where they perform poorly is during low-temperature applications. This temperature dependence makes they vulnerable to uncooperable temperature ranges. Which ultimately limits their range in application.
- Phenalkamine Hardeners – These hardeners don’t offer the best chemical resistance, nor the best color stability, nor the best viscosity. Phenalkamine hardeners are really only beneficial for water applications. They have excellent adhesion, and can tolerate a lot of water exposure. We don’t use them too often, because for every application that they could be used, a polyamide epoxy typically serves as a better alternative.
- Cycloaliphatic Amine – Cycloaliphatic hardeners are middle of the road. They have a moderate rank in just about every category (flexibility, adhesion, chemical resistance, blush and color stability, and corrosion resistance). However, the one area that they run supreme is the viscocity. They are the most viscous epoxy, which isn’t necessary a good thing. Viscocity means resistance to flow. So the greater the viscocity, the greater the resistance to flow. Which means that cycloaliphatic amine epoxy would be very difficult to spread.
- Aromatic Amine – These hardeners offer excellent chemical resistance to acids. However, the provide poor flexibility and adhesion compared to other epoxies. So these aromatic amine epoxies should be used as a top coat, and never a primer.
- Aliphatic Amine – Similar to the Aromatic Amine, the aliphatic amine offers excellent chemical resistance. But instead of resisting acids, they’re great at resisting solvent chemicals. But just like the aromatic amine, they don’t offer great adhesion or flexibility. So they require a primer on top of the substrate, before they are applied. But keep in mind, these amines also have poor color stability. So eventually, they will yellow and amber. So if you’re just looking for a high-performing top coat, then this is a great option. But if you’re looking for something decorative, then this may not be the best product to use.
Overall, between the range of hardeners and resins, an applicator has a variety of options to choose from when considering their epoxy. Depending on what type of performance they’re trying to get, and what type of substrate they’re applying the epoxy in, will determine which combination of resin and hardener will serve best for the application.