Do you need two coats of Zinsser?

Do you need two coats of Zinsser? Whether you need two coats of Zinsser depends on product and stain severity. For Zinsser Bulls Eye 1-2-3 water-based all-purpose primer, one coat is sufficient for most general priming over clean drywall, wood, masonry, and previously painted surfaces for light to medium stains. Two coats may be needed for severe water, smoke, nicotine stains, dark colors, or porous surfaces where first coat still shows shadow, or for drastic color change from dark to light. For Zinsser Cover Stain oil-based, one coat is usually enough for heavy stains, but second coat helps for worst cases. For Zinsser B-I-N shellac-based, one coat is typically enough due to strong hide and sealing, with second coat only for extreme smoke or odor. Manufacturer recommends one coat for most applications, with second if needed for complete hide. So evaluate after first coat, if stain bleeds or coverage uneven, apply second coat after recommended dry time, 1 hour for 1-2-3 and Cover Stain, 45 minutes for B-I-N. Avoid overly thick coats.