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This specification covers the basic requirements for a non-electrolytically applied, non-oily corrosion protective coating consisting of zinc phosphate treatment, zinc rich inorganic resin coating and aluminum rich organic topcoat. This finish is available in gray and black colors. It is supplied in gray color unless black color is specified.

Material Description. The coating system is free of hexavalent chromate, with no hexavalent chromate in final product per GMW3059 requirements. GMW3034 will be used as a referee test. This coating process does not generate hydrogen, however, pretreatment processes i.e. acid pickling could cause hydrogen absorption. Non-electrolytically applied zinc rich coating has high permeability, which allows effusion of hydrogen during curing that might have been absorbed during acid pickling.

Typical Application. The coating is suitable for externally threaded and non-threaded ferrous parts where high levels of corrosion protection and freedom from hydrogen embrittlement are required. When applied over steel that is to be coupled to aluminum, the coating provides exceptional galvanic protection. This coating is not recommended for internally threaded parts and parts with recess drives.

Use of this finish on threaded surface and/or bearing surface of joints could affect the torquetension relationship. It is recommended that a torque-tension study of the fastener joint be performed before releasing this finish on a new application.