It is recommended that a minimum 12 mil DFT is achieved for any marine or industrial applications for optimum protection. Rust Bullet can be applied by brush, roller, or spray equipment. The application method used will determine the number coats that are needed to achieve a minimum DFT of 12 mils. When using a roller or airless sprayer, three to four coats of the Rust Bullet Industrial will generally achieve a DFT of approximately 12 mils. It is our experience that a brush application will generally achieve a 1.5 – 2 mils DFT per coat.