Paints & Coatings Resource Center

Ask the Expert Question-and-Answer Archive

by Ron Joseph

March, 2005

Epoxy Coating Loose Gloss

Q. We use an epoxy paint following BS381C White 0055E. Concerning the loss of gloss, typical for epoxy paints. Now we paint in full gloss (>= 85%). Does the gloss level drop to a certain level and stay there? Do you know at what level it stabilize? If you paint in a semi gloss (50%), does it stabilize at the same gloss level as the full gloss? In the same time?

A. Many epoxy coatings do loose gloss when they are exposed to sunlight because of their sensitivity to UV rays. They generally do not loose gloss when they are exposed indoors. I have never seen data that tracks the loss of gloss over time, and in any case that would depend on the epoxy resin and ingredients such as UV stabilizers in the coating.

If gloss is important to you, why don't you consider using an acrylic or polyurethane topcoat instead of an epoxy? In general, most people who want to retain gloss and color during extended exterior exposure do not use epoxy coatings as the topcoat. You can use an epoxy primer followed by either an acrylic or a polyurethane topcoat, both of which have excellent sunlight resistance. Alternatively, select an epoxy that is specifically formulated for exterior exposure and good gloss and color stability.

I hope this helps.

Best wishes,

Ron Joseph

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