- Feel the wall. Oil is smooth and glossy, while latex tends to be matte and has a more rubbery finish.
- Dip a cotton swab into acetone and test the painted surface. Latex will dissolve slightly, while oil will remain unaffected.
- If you have determined the existing paint is oil-based, you must rough the surface using 100-grit sandpaper until the gloss has vanished, then wash the surface and allow it to dry. You will now be able to add the bonding primer.
Applying Latex Paint Over Oil-Based Paint
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Before applying latex paint over oil-based paint, you must first prepare the surface by sanding, cleaning with detergent, and coating with a primer. The primer can be either oil-based or latex, but in either case it should labeled as a “bonding primer.” Watch the video above to find out more. Then, read the section below for more information on combining different types of paint.
VIDEO TRANSCRIPT
If you want to apply latex paint over oil paint you have to first prepare the surface by sanding, cleaning with detergent, and coating it with a primer. The primer can be oil or latex, but in either case it should labeled as a “bonding primer.” The same is true for applying oil over latex. However, latex paints are more flexible than oil and many modern formulas are just as tough as oil, so it may be best to simply stick with latex for the new topcoat.
Why Oil Paints Don’t Mix
Oil-based paints have been used for centuries, and despite numerous innovations, a few facts have remained prominent in the artistic world. The first is that oil paints take a long time to dry. Modern oil paints dry much faster. However, they still dry at a different rate than latex or acrylics. Furthermore, if you use oil paint over latex, the new paint will expand and contract at a different rate than the underlying layer, causing it to crack. Latex will not properly stick when applied directly on top of an oil-based layer without preparation and may easily crack or peel.
There are many reasons to use latex paint over an oil primer, and the results are a strong, lasting surface. Generally, latex primers are used for drywall and softwoods, although there are a few notable exceptions. Oil primers and paints take longer to dry and require additional ventilation, meaning a blend of latex and oil can reduce time and discomfort without sacrificing durability.
Reasons to Choose an Oil-Based Primer
While some brands of primer can work universally with oil and latex paints, there are times when an oil-based primer is more efficient than a latex primer. These instances include:
- Varnished or unfinished wood
- Wood prone to bleeding tannins, such as redwood and cedar
- Painting over chalky or badly damaged paint
- Wood which has been severely weathered
- Damp environments such as bathrooms
- Can be tinted at the paint store if you will be using very light or dark colors
Determining If Your Walls Have Oil-Based Paint
- Feel the wall. Oil is smooth and glossy, while latex tends to be matte and has a more rubbery finish.
- Dip a cotton swab into acetone and test the painted surface. Latex will dissolve slightly, while oil will remain unaffected.
- If you have determined the existing paint is oil-based, you must rough the surface using 100-grit sandpaper until the gloss has vanished, then wash the surface and allow it to dry. You will now be able to add the bonding primer.
Published on May 4, 2023
Solved! The Rules for Painting Over Oil-Based Paint
By Manasa Reddigari and Bob Vila | Updated Feb 8, 2021 3:47 PM
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Q: I’d like to repaint my kitchen cabinets, which had been done with oil-based paint. Must I use oil-based paint for the project, or can I use up some water-based paint I have left over from another job?
A: You’re correct to assume that it’s generally best to use more oil-based paint—in either an alkyd (made with a synthetic resin binder) or natural oil (such as linseed) formula—to refresh surfaces already coated with oil-based paint. Using water-based or acrylic paint when painting over oil-based paint is likely to cause peeling or chipping because those formulas don’t bond well with the naturally glossy surface of oil-based paint.
Yet it’s easy to understand why you’d want to go with water-based paint—it boasts lower volatile organic compound content (and less smelly fumes), faster drying time, and better resistance to discoloration from sunlight. Fortunately, with the proper approach, you can successfully use water-based paint over oil-based paint. Ahead, you’ll find pointers for using whatever paint products you like over oil-based paint.
Using Oil-Based Paint Over Oil-Based Paint
- Paint cured oil-based paint with either type of oil-based paint. If oil-based paint (either an alkyd or natural oil formula) has fully cured, it can be repainted with either alkyd- or natural oil-based paint. Oil-based paint is considered fully cured when it has hardened to the point that it can be scrubbed or washed without affecting the finish, which can take seven to 30 days.
- But avoid painting alkyd over uncured natural oil-based paint coats. If dealing with natural oil-based paint that hasn’t yet cured, only repaint with natural oil-based paint. If you were to apply alkyd paint, the natural oil-based coat below would continue to harden after the alkyd coat has cured, causing the top coat to crack. Alkyd paint that hasn’t yet cured, on the other hand, can safely be painted with either alkyd or natural oil-based paint without fear of cracking the top coat.
