Q. How do I know when to use a sealer?
Brian Santos: Use a sealer before painting porous surfaces such as these:
- Any unpainted surface, including new plaster, drywall, and old woodwork that has been stripped.
- Bare open-grained woods such as oak and maple.
- Bare woods, such as redwood, that bleed through or discolor paint.
- Large areas of wallboard joint compound or patching plaster.
- Masonry surfaces like unglazed brick, cinder block, and concrete.
- Metal surfaces; use an oil-based primer-sealer with rust inhibitors to prevent corrosion.