Almost all paint manufacturers make primers. Primers are often used as undercoats, when a significant change of color is in the cards; they reduce the number of paint coats needed to cover the surface, thereby reducing the cost of the job (as primers are less expensive than premium paints). But primers also cover stains, block odors, and help resist mold. Hayward Paint Centers carries many of these specialty primers, and their knowledgeable sales people can advise you on which primer best fits your needs.
Hayward carries these specialty primers:
○ Cover Stain, Shieldz and other specialty primers by Zinsser