How To Tell If Original Paint Is Oil-based

Testing your item, wall, door, etc to determine the type of existing paint is key to repainting any surface. You will not be able to paint over an oil-based paint with a water-based one with any success unless the surface is primed with a specific primer or unless you sand the gloss from the surface. Lightly sand the surface to dull the glossy finish (wearing proper safety gear, like a respirator) then clean the dust and dirt particles from the surface prior to painting. Even if you sand the glossy surface down, I would still recommend priming it to produce the best results.

SUPPLY LIST:

Cotton ball, cotton swab, or rag
Rubbing alcohol, or acetone based solvent

Instructions:

Apply rubbing alcohol to a cotton ball, cotton swab, or the corner of a rag and rub it on the clean and dry door. If the color rubs off onto the cotton ball, you have latex paint and can apply latex (acrylic) to the door. If nothing rubs off, it is painted with an oil-based paint and you can paint over it with an oil-based paint, or you will have to use a bonding primer like Kilz Adhesion Primer to paint over it with a latex paint. The primer is water based but specifically formulated for these situations. Read the directions on the primer can for best results. Follow the Painting Steps to apply primer.