Rust-Oleum 1913-830 1913830 Chalkboard Spray, Black, 11-Ounce Ideal for creating a custom interior chalkboard on multiple surfaces including wood, metal, masonry, drywall, plaster, glass, concrete, paperboard and hardboard Apply the oil-based formula to create a hard surface for chalk writing on most indoor surfaces Covers up to 7 sq ft and dries to the touch in 20 minutes Creates a chalkboard that is scratch resistant, smooth and erases easily after use For optimal results before writing on surface, wait 24 hours after application and condition surface for use by rubbing side of chalk over surface and erasing