The AP Plaster Primer WB (3 in 1) 20LT - Alpine is a high-quality water-based primer designed for plaster, drywall, and cement surfaces. Its 3-in-1 formulation acts as a primer, sealer, and undercoat, ensuring excellent adhesion, smooth finish, and enhanced paint durability. Ideal for both interior and exterior applications, it provides a strong base for all subsequent topcoats, improving coverage and finish quality.