WATER-BASED
BEST FOR
Preparing previously finished surfaces, including drywall, concrete, fiber cement, stucco, metals, fiberglass, and PVC.
PROS
Low odor; fast drying; cleans up with soap and water; adheres well without sanding; blocks oily stains.
CONS
Water will rough up raw wood and MDF, and cause cedar and redwood to bleed.
ONE TO LOOK FOR
KILZ Premium Interior/Exterior Multi-purpose Water-based Wall and Ceiling Primer, $23 per gallon; Lowe’s
OIL-BASED
BEST FOR
Coating raw wood, MDF, spackled spots, and rust-prone steel or wrought iron.
PROS
Penetrates wood without raising grain. Blocks water and mildew stains, cedar and redwood bleed.
CONS
Requires good ventilation during application and mineral spirits for cleanup.
ONE TO LOOK FOR
XIM 11301 1G X-Seal Alkyd Primer/Sealer/Stain Blocker, $30 per gallon; World Paint Supply
SHELLAC-BASED
BEST FOR
Spot priming exterior rust stains and knots. Sealing smoke damage and odors. Prepping glossy, greasy surfaces without sanding.
PROS
Works on all surfaces and blocks all stains and smells; some DIYers rely on it to seal cut edges on MDF.
CONS
Pricey. Strong odor when wet. Cleanup calls for denatured alcohol.
ONE TO LOOK FOR
Zinsser B-I-N Shellac-Based White Interior/Spot Exterior Primer and Sealer, $45 per gallon; Home Depot