I’m repainting my house, but I’m not sure what kind of paint was originally used. Is it okay to put latex paint over oil-based, or is it the other way around? -Howard
In order for your new paint to form a good bond with the existing paint, it’s important that the two paints are compatible. Don’t apply oil-based paint over latex; but you can put latex paint over oil-based, as long as you prepare the surface properly first.
Start by finding out if the existing paint is oil or latex by rubbing the surface with denatured alcohol on a rag. If some of the paint comes off on the rag, it’s latex. If not, the existing paint is oil-based.
To apply latex paint over oil-based:
- Lightly sand the surface with fine sandpaper (180 to 220 grit) to remove the gloss.
- Clean the surface with a sponge dipped in a solution of TSP (trisodium phosphate) mixed with water.
- Remove the cleaner with a sponge and clean water, then allow the surface to dry.
- Apply a coat of a quality bonding primer (oil-based or latex), and allow the primer to dry.
- Topcoat with two coats of high quality latex paint.
Watch this video to find out more.
- Applying Latex Paint Over Oil-Based Paint (video)
- Homeowner’s Guide to Paint Primer (article)
- When to Prime Before You Paint (article)
Howard asks: I’m repainting my house, but I’m not sure what kind of paint was originally used. Can I use latex over oil, or should it be the other way around?
Danny Lipford: Now, that’s a great question. But before we answer the question, we have to determine exactly what kind of paint you have on your woodwork right now. Here’s an easy way to determine that. First of all, take some denatured alcohol, put it on a rag, wipe the woodwork, and if any paint comes off on the rag, then you have latex paint.
Now, you never want to paint oil over latex. It just won’t stick. But you can paint latex over oil-based paint, if you prepare the surface properly. First of all, take a little bit of sandpaper and just lightly sand it. Then you want to use some trisodium phosphate, or TSP, you can find it in any paint store or home center. Then, after that dries, use a good bonding primer. Put one coat of primer on it. After that dries, you’re ready to finish up the paint job, and you’ll know that it’ll last.