Have you ever wondered if you need to prime your walls before painting? Well, it all depends on the existing surface. A primer creates a strong bond between the existing surface and the new coat of paint. If you are applying a light color over a darker one, using a primer tinted with the final paint color is a great choice for insuring maximum coverage with only one or two top coats.
A surface you always want to prime before painting is bare wood. Priming bare wood helps to create a seal over the porous wood allowing the paint to stay where you put it, on the surface.