Standard Finish The exterior surface is cleaned with an alkaline rinse to remove surface contaminants and shot blasted to specifications as published by The Society for Protective Coatings SSPC-SP 10 (near-white blast cleaning). The exterior surface is chemically pretreated with an iron phosphate conversion coating then rinsed with ambient fresh water containing special surfactants and sealers forming a dry tight micro-crystalline coating. A polyester thermosetting powder coating applied to the surface of the substrate to a minimum of 3 mils is standard on all color finishes.