Finishing Over Pre-Finished Plywood

Pre-finished plywood takes additional coats nicely, pros report. December 10, 2007

Does anyone have tips for spraying pre-finished plywood (UV clear coat kind)? I will be shooting with an HVLP gun, using a white tint, Sherwin Williams acrylic paint. I expect to lightly scuff the surface, prime, and spray. My first cab job with pre-finish!

Forum Responses
(Cabinetmaking Forum)
From contributor R:
Please don't celebrate until you have done an extensive pre-test of your finish on a decent size pre-finished test panel. I've tried many types of finishes over a pre-finished sample board, and although they looked great, I was able to easily scrape the cured finish right off with my fingernail.

From contributor J:
I use 80 grit sand paper to sand the finish off, just seems safer to me. I don't have to do it very often. I usually use MDO for painted work. Once in awhile, though, I'll need maple on one side and painted on the other, and then the sander comes out. By the way, the finish on Norbond ply is a real pain to get off. Don't know about other plies, but that stuff is tough!

From contributor E:
Maybe I am missing something, but why would you want to finish pre-finished plywood?

From contributor V:

I asked the same question of my MLC rep. I'm currently working on a kitchen that the client wants a painted finish on. I'll always use pre-finished maple for my casework and simply spray the face frames and doors. This one will have several glass doors showing the cab interiors. Rather than mix materials and lose yield from my sheet goods, I asked my MLC rep if I could spray over the finish for the few cabs that need it. Could I let the pre-finished act as my base coat and color it out from there? He said "absolutely!" He said it's a harder finish than anything I could spray on myself. As long as I treat it as an intermediate coat and scuff sand to prep it, I should have no problem. He was right. I've just finished doing that this weekend, and they look and feel great. I still primed white before the color, and the finish is hard as nails. One bonus was no grain raise like I'd normally get from paint grade ply. I think the key is to scuff it well, especially since it is a harder finish. It definitely works.

From contributor B:
I have scuffed the UV and primed with Clawloc. No problems!

From contributor P:
Contributor V is right on with what I am doing. I have a full kitchen built to go with pre-finished. The face frames and doors are white, cottage style kitchen. I have a few painted ends with faux doors mounted to the cab sides. Rather than wasting my time getting raw stock, I just wanted to flow with my pre-finish which was ready to go. Plus I didn't want a different look of pre-finished cabs over 90% and non for the few end cabs. I wasn't looking to skin them either. Not my style, and that's what most of this boils down to, your style of making cabs.

Thanks for the info and I look forward to shooting them this week. Did you scuff with 220 or higher/lower?

From contributor E:
Okay, I think I'll try it too. It just seems like you have to scuff it as hard or harder as you would have to scuff your primer, so is it really worth it cost-wise?

From contributor V:
I started with 220, but I was a little unsure about the results, so I hit it again with 180 instead just to make sure I could scuff down that finish. Let me tell you, this finish looked like melamine when I was done. Not a blemish.

It wasn't really any extra effort. It's more the convenience of not having to mess around with a second lot of ply when I'm only having to color a few panels.

From the original questioner:
What primer did you use? I will be shooting white as a primer and a shade of white for the final.

From contributor V:
I'm using ML Campbell's Magnaclaw for primer and Magnamax as my topcoat for this job (white primer, White Dove finished color). I've used SW in the past and they have a good product, but I prefer MLC.