We recently moved into an older home and have been busy doing interior repainting. We are doing basic off white and the walls, which were a flat off white cover quite nicely with one coat of semi-gloss latex paint. My problem is with the doors and casings which were painted in a gloss (don’t know whether it was oil or latex but I suspect the latter). Those surfaces cover poorly and require two coats which I don’t mind but the paint, once dried, has a tendency to chip quite easily.
Any suggestions on how to improve the adherence of the new paint to the old glossy finish.
Thanx in advance for any help
Replies
Henry,
Use either an oil based bonding primer or Bins Zinseer sealant. Both work well for this. I also wash the surface down with a scotchbrite pad and TSP cleaner before I start priming. DanT
If you want to get real ambitious, and the moldings have detail almost obscured by layers of paint, remove the molding, mark on the back where it goes, and strip all the paint off (pull any finish nails through the back to save the front face.)
You might be surprised what's buried beneath the years. (Beware, old house and trim usually mean lead paint.) When the stripper has done its work, use scrapers and sandpaper to remove the residue and bring the molding back to life. Clean the molding, apply two coats of primer (I use Kilz) followed by 1 or 2 coats of paint. Reapply molding to doors/windows, set nails, putty and touch-up paint. Viola!
The procedure is time-consuming and a lot of hard, stinky work, but worth it when you're finished. (Just another option to consider.)
When you paint over an older glossy surface, there is little mechanical grip or "tooth" to bond the layers together. There is only the chemical bond. If the old surface is dirty or greasy, even the chemical bond is broken.
To solve the problem, scarcify the old surface with a TSP washing which also removes the oils and residue. Rinse. If still too slick, sand it with 180 or 220 paper.
Of course taking it all the way down to bare wood is best but without seeing the situation I couldn't recommend that.
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You can buy a jug od "deglossing agent". I know all paint stores as well as HD carries it.
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Of course proper prep is everything, and only quality paints need apply. I can't imagine an interior re-paint that shouldn't be sanded, filled, spot primed. I also can't imagine a re-paint that doesn't require two coats, (except flat over flat).
As mentioned, clean the surface, then test to see what is on there. Rub with denatured alcohol, and if the color rubs off it is latex. If so, prep/prime/paint.
If the color doesn't rub off it's oil/alkyd, and you really should use an alykd based primer as a bonding coat. I like alkyd Kilz, but you can mix that with, (or use instead), an alkyd undercoater to extend the flash time and provide more body.
Deglossers are more or less a do-all miracle in a can, combining agents that will cut into most any finish. At a minimum they will clean and provide a reasonable surface for coating, but I would be reluctant to depend on them. They are also some nasty to work with, and don't replace proper prep.
I had the same problem when we moved into the 100 year old house we are in. Here is what I was told by the local paint suplier. The original finish on the wood work was oil base. The next coat someone put on was latex. More importantly, the elderly woman who owned the house was a smoker. The nicotine adheared to the oil base finish and when the latex was applied it reacted with the nicotine and the and created a "paint stripper". Not only did the paint chip, after a year in the house I could actually pull the paint off the door in larger sections. I ended up holding 16" x 30" pcs of paint that had the contour of the panel door. Wash the woodwork down with a good detergent, apply a coat of primer (BIN by Zinzar is what I used) and the paint will hold.