Rust Bullet works best when it is in direct contact with the substrate; remove as much existing paint as possible. If there are areas that are tightly adhered, create a proper profile for adhesion by sanding the existing paint with 80-100 grit sandpaper. This will provide an anchor pattern to the surface before applying Rust Bullet Concrete coatings.
Note that if the existing coating is failing, Rust Bullet will be subject to this same behavior because it is adhered to the failing coating and not the substrate itself. Only apply to existing coatings that are in good condition and exhibit strong adhesive properties. For the best results, it is recommended to remove all existing coatings prior to application of Rust Bullet Concrete coatings.