We have an interior door that was originally stained and varnished (?), then painted at a later time. The paint isn’t holding to the finished wood; in fact, it’s lifting off fairly easily. I’m scraping it off. (There are only two layers of paint, so it’s probably not lead-based.)
The paint layer next to the wood is tan, so I’m assuming it is not primer. I don’t know whether it’s the varnish or the lack of primer that is keeping the paint from adhering.
Is it necessary to sand away the varnish before repainting–or will a coat of primer be sufficient?
Janet
Replies
If the varnish is sound, not alligatored or flaking, it doesn't need complete removal. What could have kept the paint from adhering is dirt. If the varnish wasn't well cleaned of both waterborne and oily dirt it could harm adhesion. Also, it should have been sanded with 220 grit (give or take) to provide some "tooth" for the paint to adhere. And, yes using primer is needed. A shellac based primer offers good adhesion.
I hate to bump heads with somebody like Steve Shoene but it is my experience that paint adhesion to varnish can be somewhat flaky (pun intended).
It may well be down to the actual varnish and paints involved but on the rare occasions when I paint over varnish I remove the varnish aggresively.
However I have not tried using a primer. Except for marine work I use 2 coats of undercoat and 2 or more of topcoat. Boats get primer.
I agree with Steve. If you get it down to a smooth surface, even with paint/varnish left on, prime it well and then repaint. The shellac that Steve speaks of could be BIN primer.
The other thing to think about is oil or latex. The paint layers could also have been latex applied without proper prep of the door, be it grime, as Steve suggested, or just painted on varnish.
Still having problems with poor adhesion.
I used bin over both varnished and sanded surfaces, then a coat of alkyd paint. Sanded it lightly before applying a second coat, and some of the paint flaked off. This was even over places where I had sanded the varnish away.
Could I have sanded the surface too much? A paint rep told me the surface needed to be clean, dry, and rough, but I didn't want the paint to look rough so I sanded the wood with 180 grit.
Janet
What about cleaning? Did you scrub the surfaces with TSP and water and then with naphtha, using plenty of towels so you don't just smear it aroung? Though it seems strange, even sanding doesn't remove old dirt and grime. This would be most important if these were doors near a kitchen.
Using 180 grit should not have been part of the problem, that's plenty rough.
Steve,I agree. On those old doors it was common to use Old English, Murphy's Soap, lemon oil etc. even though they were varnished. Later years, silcon wax products.The biggest single culprit on paint adhesion is poor prep and the biggest part of that is degrease and de-oil/de-grime. TSP and Naptha followed by a good tooth sandpaper and shellac based primer.BB
arghhh, no, I didn't wash the surface. Just scraped/sanded and followed up with a tack cloth. Well, next time I'll know what to do. Thank you.Janet
One more thing. Tack cloths can be another source of problems. Best just a cloth or towel dampened with naphtha.
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