Primer / sealer

A primer (or primer-sealer) is a preparatory coat applied before the topcoat. It does three jobs: it seals porous or repaired surfaces (new plaster, filler, gypsum) so they don't drink the paint unevenly; it helps the topcoat adhere so it doesn't peel; and the right primer blocks stains so old marks don't bleed through. Skipping it — or using the wrong type — is behind a large share of paint jobs that look patchy, peel, or let a brown water stain bleed back through within weeks. On bare, repaired, stained or glossy surfaces it isn't optional. A good painting and finishing specialist matches the primer to the surface as part of proper prep.