There are many, many different blends. Tnemec Co. Inc. The same goes for surface preparation. Plus, every application situation will be different. You have to know what the substrate is, what it's exposed to, and what it's been exposed to in the past to determine how to prepare it properly and to know if the right system has been selected. But what we can do is give you some things to keep in mind because contrary to popular belief, an epoxy is not an epoxy.
Differences are incremental.
Most offer good chemical resistance, but some are stronger than others. Polyamide epoxies are good as general maintenance coatings on steel or concrete. Polyamine epoxies also offer good chemical resistance, but especially on the acid side of the pH scale. Coal tar epoxies exhibit high water resistance characteristics and are good for water treatment applications. They're also often used for the exterior of pipes that are to be buried.