Note: This post is part of a larger series on generic coating types. Click the button at the bottom of this post to download the entire guide.
Epoxy primers and finishes make up a versatile line of coatings in an industrial applicator’s arsenal. They are usually formulated from an epoxy resin and some sort of curing agent. Commonly referred to as the “workhorses” of industrial coatings, epoxies serve under a wide variety of settings and conditions. In general, due to their aesthetic limitations—properties such as poor color and gloss retention—they are often paired with a polyurethane or some other type of finish coat.
Epoxies are products that have made strides in the high and 100 percent solids categories. These high film build formulations are more environmentally friendly, while still offering excellent chemical, abrasion and water resistance qualities.
The type of epoxy resin used in a coating will determine its physical and chemical properties, with bisphenol A, bisphenol F and phenolic novolac being a few of the most commonly used. Because epoxies make up such a diverse coatings group, benefits and drawbacks listed here will refer to epoxies in general. Characteristics will vary based on the specific formulation used.
- Excellent chemical resistance
- Excellent corrosion resistance
- Good adhesion to many substrates
- Long cure time in cold weather
- Poor color retention
- Poor gloss retention
Excellent barrier protection makes epoxies a go-to favorite when corrosion and chemical resistance are a concern. They are often used in marine environments where full or partial immersion of the substrate will occur. This could be in the case of offshore oil platforms, bridges, petrochemical plants, hydroelectric facilities and so on. Additionally, certain 100 percent solids formulas perform extraordinarily well as interior tank linings.
Though epoxies can be formulated to act as primers, intermediate or finishing coats, they have been shown to be especially effective for long-term corrosion protection as intermediate coats between a zinc primer and polyurethane finishing coat.