Finishing Over Epoxy Acrylate

It's an all-solid UV-cured finish, probably very hard but maybe brittle. February 8, 2008

I'm no chemist! Our pre-finished plywood is finished with epoxy acrylate. What is it? I have primed (vinyl primer) over this before to make it a solid color without problems, but that doesn't mean it's okay to do that. Is it solvent, water, other?

Forum Responses
(Finishing Forum)
From contributor A:
UV cured. I always assumed the UV cured finish on pre-finished plywood was a urethane.

From the original questioner:
I did understand that it was a UV. Does that mean that it isn't classified as either solvent or water? The question that I didn't make very clear is, can it be finished over without adhesion problems as long as I scuff it? Can I spray a vinyl primer on it to make it a solid color? This is not something I would do a lot. Just asking.

From contributor J:
Are you sure this is the finish they used? From what I was told and what I have seen, the large manufacturers use a water based finish that is UV cured. Usually from Sherwin Williams, designed just for them.

As far as finishing over it... Just make sure you sand it thoroughly. The finish you apply won't bite into that finish and bond, but if you scratch it enough, your finish will grab onto the ridges and use that to hold on.

I have finished over pre-finished plywood many times with nitrocellulose lacquer, acrylic polyurethane, polyurethane, and solvent based white primer. I know nothing about water based finishes, so I can't comment on those yet.

From the original questioner:
That is what their site says. They give specs for it also. I also was under the impression it was a water base UV.

From contributor C:
Generally speaking, an epoxy acrylate is 100 solids UV coating, not water, not solvent - 100 percent solids. Epoxies are used in roll coat for plywood because they are cheap. If it was flooring urethane acrylates are the main backbone. UV epoxies are very hard, sometimes brittle coatings. I would sand and do a test board, let product dry, and do a cross hatch test.