ASTM F1137/F1137M-19

1.1 This specification covers the basic requirements for six grades of corrosion protection for fasteners. Grade A consists of a heavy zinc phosphate coating with no additional sealer (dry), Grade B consists of a heavy zinc phosphate coating with a dry organic sealer, Grade C consists of a heavy zinc phosphate coating with supplemental dry-to-touch oil type compound, Grade D consists of a heavy zinc phosphate coating with supplemental protective oil type compound, Grade E consists of a grain-refined microcrystalline zinc phosphate with supplemental oil type compound, and Grade F consists of a manganese phosphate coating with supplemental oil type compound.