by Salim Brahimi, Industrial Fastener Institute
In the 1990s, an electroplated coating of fasteners was considered straightforward and was simply specified by zinc thickness (0.2 to 0.3 mil, or 5 or 8 µm, for example) often followed by passivation in chemical solutions containing hexavalent chromium Cr (VI), and without any requirement for corrosion resistance.
It is important to note that ISO 4042, same as ASTM F1941/F1941M, is a fastener electroplating standard that covers all electroplated coatings applied to fasteners. These standards are in contracts to ASTM B633 for example, which is a general zinc electroplating standard that does not address fastener-specific concerns (e.g., thread fit, etc.).