Do you need two coats of Zinsser primer?

Whether you need two coats of Zinsser primer depends on surface condition, stain severity, and topcoat color, but in most cases one coat of Zinsser primer is sufficient, with second coat only needed for severe stains or drastic color changes. Zinsser primers like Bulls Eye 1-2-3 are marketed as one-coat primers for most surfaces, including drywall, wood, and previously painted walls, and they provide good adhesion and hide for topcoat in one coat. For new drywall, one coat of Bulls Eye 1-2-3 is enough before two coats of paint. For covering light stains or painting over similar color, one coat suffices. However, you may need two coats when covering severe water stains, smoke damage, nicotine, dark colors, or knotty wood, as first coat may allow some bleed-through, especially with water-based primers. Zinsser BIN shellac-based primer often blocks severe stains in one coat but second coat may be needed for worst pet odor or smoke. Manufacturer recommends two coats for best stain blocking on heavily stained surfaces. Applying second coat too soon can cause lifting, so follow dry times, typically 1 hour for water-based and 45 minutes for shellac before recoat. Using two coats of primer is cheaper than using extra topcoats to hide stains, so for tough jobs, two primer coats save paint. For most interior repainting, one coat Zinsser plus two coats paint is standard practice.