Plywood cabinets often have a raised grain, rough texture or knots that bleed. Primers smooth and hide these minor imperfections, creating a flawless canvas for paint. Paint adheres smoothly to a primed surface for fewer chips and a more durable surface, which is especially important for kitchen cabinets that take a lot of wear and tear. Primers also hide stains and keep paint colors true.
A basic primer is usually adequate for most plywood cabinets, but if yours are stained, try a stain-blocking primer. Oil-based primers are smelly, take longer to dry and are difficult to clean up, but they provide a more durable finish than some enamel primers.
Before priming and painting kitchen cabinets, clean them thoroughly to remove dirt and grime. Repair or replace broken hinges and runners and remove hardware. Lightly sand cabinets finished with a stain or sealer. Remove cabinet doors to paint them. Brush one coat of primer on and allow it to dry thoroughly before painting. Apply two to three coats of water-based urethane after painting cabinets to increase durability.
Old, vintage cabinets may already have multiple coats of paint on them, so you're unlikely to have problems with rough edges, grains or bleeding sap. In this case, you may not need primer, especially if you are painting the cabinets the same color. Be especially careful with the cabinets to avoid nicks and dings during the first two to three weeks after painting, until the paint has cured and hardened.