That's odd! Each can of Rust-Oleum Specialty Chalkboard Paint has a recommended coverage of 95-120 square feet per a single coat. It is essential that enough product is being applied to the surface and that the surface is being properly prepped. To ensure ease of erasability, the surface must be conditioned before use and after every time the surface is washed. We recommend waiting at least 3 days before writing on the surface and 7 days before wiping the surface down.
- Rust-Oleum Product Support 3