Ask the Expert Question-and-Answer Archive

by Ron Joseph

June, 2004

Painting Epoxy Coatings in High Humidity

Q. What is the maximum humidity level, in the atmosphere, that I can spray an epoxy primer? I am covering bare metal and live in a humid part of the country, 60 - 100% most of the year.

A. Thank you for your e-mail. I'm not aware of a maximum humidity when applying an epoxy coating. I know, for instance that ships are constantly painted with epoxies while they are exposed to very high humidity is especially when they are already in the ocean. Therefore, my advice is to try to select a day on which the humidity is at the low end of the range that you normally experience in your local area. Also, I suggest that you apply the epoxy immediately after you have mixed the two components. Preferably, do not leave the mixed coating uncovered for any length of time before you apply it to the substrate.

Finally, try to schedule the painting operation during that part of the day when the substrate is completely dry. Therefore, if due has formed during the night you should wait until the sun has evaporated all the moisture from the surface before you start painting.

I hope this advice will be helpful to you.

Best wishes,

Ron Joseph