How to Apply Water-Based Paint Over An Oil-Based Surface

LOS GATOS — While environmentally-friendly materials offer a healthier approach to home improvement, they aren’t always compatible when used alongside traditional ones. One example of this is using a water-based paint on an oil-based surface.

While it may take a while to show, when water-based paint is applied to an oil-based surface, it results in problems. This is essentially due to the well-known rule that oil and water don’t mix. Because of the new coat’s water-based constitution, it will fail to bond properly with the existing oil-based surface and eventually start to peel right off the wall.

Since many homes contain oil-based surfaces, if you’re planning to use a water-based paint product, you should first determine the character of the surface you’ll be painting over. Fortunately, testing a surface is fairly easy: simply soak a Q-tip, cotton ball or clean rag in rubbing alcohol and rub it over a small section of the wall. If paint comes off, it’s water-based; if not, it’s oil-based.

If you find that a surface is oil-based, you’ll need to properly prep the area before applying a water-based paint product. Preparation consists of two basic steps: completely sand the area and apply an oil-based primer. Once your primer coat is dry, you can apply your water-based paint.