OSB - Skim then Prime or Vice Versa?

[Steve Canada]

Simple question for those who've done it:

Do you skim coat your OSB AFTER you prime or before. Logic would say after you've sealed, no?.

[NICK BARBOZA]

skim with what? drywall mud? if so, doesnt matter when you do it, it wont work.

Nick

[David G Baker]

I use drywall primer under a couple coats white high gloss paint. This is what I use for the ceiling in my shop and the upper half of the wall. It is difficult to tell that it is OSB when finished.
Never heard of skim coating OSB if you mean the same thing as skim coating a drywall surface. It could work but you will have to find out from someone that knows a lot more about it than I do.

[Jon Crowley]

My gut feeling is that skim coating with drywall mud would not work. The OSB will have some amount of flex, and I could see it easily cracking and flaking off if it bends at all. I vote for just primer + paint.

[Prashun Patel]

I've only had luck painting OSB with shellac based primer (Zinsser BIN). Even then, it's hard to completely hide the occasional chip line.

[John Keeton]

I somewhat agree with Jon on the problems of flexing and the compound breaking loose and I think you would have a real difficult time getting a smooth surface.

But the real problem - it is WAY too much work. Why do that? A number of options would be better depending on the ultimate goal. If you are wanting a smooth surface, just screw 1/4" sheetrock to the OSB, mud and tape, and finish like normal drywall.

I guess I am missing the goal of the project? I have primed and painted OSB and obtained a suitable finish for a workshop. David has the best answer.