Making Acrylic Paint Stick Over Oil Paint
Quick answer: shellac primer. July 29, 2007
Question
We re-finish a lot of wood trim and cabinetry in San Francisco that is already oil based. It is convenient to re-finish in oil because, from our experience, oil sticks to oil so much better. We have walked into countless jobs where the previous paint job was latex over oil and coming off in sheets. We have converted many homes from oil to acrylic finishes, but only if we prime using great adhering water-based primers. When I ask companies about a semi-gloss acrylic that sticks to oil as good as a primer, they have few answers. Why is it so hard to find an acrylic finish enamel that will stick to oil as good as an $18 per gallon primer? Is there an industrial product out there that can be trusted to fit my needs?
Forum Responses
(Finishing Forum)
From contributor C:
Let me make sure I understand. You are refinishing cabs and trim that have previously been finished with a short or long oil alkyd pigmented finish, with fresh coats of the same. Is this after you've stripped and sanded the bulk of the old finish off, or are you just feathering the damages and filling and then applying fresh coats?
From the original questioner:
Sorry if I was unclear. In this scenario, we are not stripping the wood, merely re-painting wood trim, cabinetry, moulding, etc., that was previously finished with oil based pigmented paint. (In this case, not varnish, lacquer or any clear finishes.) That is why I'm interested in a water based enamel that will adhere to oil based enamel. While we have stripped entire homes of their wood finishes, this is not the common request of our clients, as it can be costly, of course. I should mention we spray as much as possible with a Kremlin Airmix and would like to continue to do so with any new product.
From contributor A:
When I do any kind of finish work and I don't know what the existing finish is, I spray or wipe on wb shellac. Shellac can be used as a binder coat for anything (I think). If you were going to put 2 coats of latex paint over the oil, you might be able to do 1 coat shellac and 1 coat latex.
From contributor C:
Your problem is not new or unusual. For decades I've used Zinnser bin primer, a shellac base pigmented primer that sticks extremely well to oil base or virtually anything else for that matter. After you have applied this, you may use any professional latex paint over the top of it.
