Most folks find out about stains and problem surfaces after it is too late — during, or after they are done, painting. Repeated coats of paint won’t cover properly because the problem areas bleed through the new paint.
Special Problem Areas
Old paint, oil or lead based
Grease, oil, mold, or mildew
Graffiti, ball point ink, permanent markers, paint
Bad plaster, crumbling or water damaged
Old oil and lead base paints often used special pigments that bleed through new latex paints. Light colors might not bleed at all while some darker colors cannot be covered even with several coats of paint. You can test a small area, let it dry for 24 hours, and check for coverage.
To seal the old paint, you need to use a special primer. Normally, it will be an oil base primer especially made to cover oil base paint before painting with latex paint. Be sure to get one designed for this purpose. Be sure to follow the directions for drying time before applying the first coat of paint.
Grease, oil, mold, or mildew should be cleaned with a household clearner first. Next, clean with a solution made for use before painting, such as Soilax. You can purchase it at a paint or hardware store. After the soiled areas are dry, paint them will a special primer designed for hiding these kind of spots.
Porters–Stay-Kill–primer works well. You can prime the entire surface, or just cover up the soiled areas. Be sure to follow the directions for drying time before applying the first coat of paint.
