This specification covers the basic requirements for a barrel or rack electrodeposited zinc alloy plating system over a ferrous substrate. A plating system consists of; zinc alloy plating, a zinc-alloy surface treatment (e.g. trivalent chromium conversion coating), and may include a post treatment. All zinc alloy surface treatments and post treatments must be hexavalent chromium free. Four alloy plating’s are covered by this specification: zinc-cobalt, zinc-nickel, zinc-iron and zinc-cobalt-iron. Zinc alloy plating is especially suitable for small to medium ferrous parts such as castings, fasteners, stampings, clips and other parts where levels of corrosion protection exceeding pure zinc are required. Table 1 lists the zinc alloy finishes covered by this specification and their alloy concentration limits and % nominal. NOTE: This finish is not recommended for applications where white corrosion is a cosmetic concern.