PPC Prep ensures the best adhesion for all paint coatings on metal surfaces, this also includes aluminum and shiny polished metal surfaces. PPC Prep gently etches metal, creating an ideal base for coatings whilest leaving a zinc phosphate coating to insure chemical bonding of paint and steel. Avoid other preps that may leave harmful residues which prevent proper adhesion. After using PPC Clean, ensure you use PPC Prep to both neutralize any rust and etch any clean bare metal. This will allow better adhesion of your desired coating. PPC Prep is not caustic, corrosive, toxic or flammable.