When should you prime a spot rather than the entire surface?

• A. Always prime entire surface
• B. On porous or stained areas, repaired sections, or when adhesion is uncertain.
• C. Only prime after painting
• D. Never prime the surface

Answer: (B)

Priming should be used where the paint finish would be affected by surface conditions, not on every surface all the time. The best practice is to spot-prime porous or stained areas, repaired sections, or when adhesion is uncertain. This seals porosity so the topcoat doesn’t soak in unevenly, blocks stains or bleed-through (like water or tannins), and helps patched or repaired spots accept the paint uniformly. It also reduces the risk of adhesion problems on slick or unknown substrates by giving the topcoat something good to bond to.

Prime the entire surface only when the whole area has those issues or you’re aiming for a uniform finish across the whole surface. Priming after painting is incorrect, and never priming is not appropriate when you have porous, stained, or poorly adhered areas.