Even though they say “water and oil don’t mix,” that doesn’t necessarily mean you cannot use latex paint to paint over something that was originally painted with oil-based paint.
If you have purchased a piece of old painted furniture at an antique store or live in an older home, it’s likely that the furniture or some of the woodwork, cabinets, or doors were painted with oil-based paint.
What would happen if you apply latex paint onto an oil-painted surface? Simply put, the paint will dry, but it might not stick very well. In some cases, you would be able to peel the paint right off. However, this does not mean that it is impossible to paint over an oil-painted surface with latex paint – all you need to do is take the proper steps to prepare the surface.
First it is important to determine whether the surface is actually coated with oil-based paint. To do this, take a cotton ball or a small rag and dip it into some denatured alcohol, then rub it over a small area on the surface. If the paint does not come off it is oil-based paint. If the paint does come off, it is a water or latex-based paint.
When it’s time to get to work, prepare the surface by using 150-grit sandpaper to sand all the rough spots. Sanding is an important step to do before priming, as it will roughen the surface a little and give it better adhesion. Next, sand lightly again with 220-grit sandpaper until it is nice and smooth. After sanding be sure to clean off any leftover dust on the surface.
To assure that the latex will have a nice finish with good adhesion, be sure to prime the surface with a good quality primer. While some paints are designed to go directly over oil-based paint without the need for priming, you should still make sure that the surface is clean and sanded thoroughly in order to get good adhesion.
In short, you can paint latex paint over oil-based paint, but only if you make sure to take the proper steps to prepare the surface. Start by testing to see if it is oil-based, then sand and prime, and finally, apply your latex paint.
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