Zinc deposited electrolytically, typically 5 to 12 microns thick, then given a chromate or trivalent passivate that tints it clear, bluish, yellow or black and adds some corrosion resistance. It is cheap and bright but protects modestly compared with zinc flake or galvanizing. Parts harder than about 39 HRC risk hydrogen embrittlement from the cleaning and plating steps, so they need a relief bake.
Yellow zinc plating is fine on the brackets, but the Grade 8s need a bake cert or we switch them to flake.
Also heard as
- electroplated zinc
- clear zinc
- yellow zinc
- electrogalvanized
Related terms
Bake
To heat plated high-strength fasteners soon after plating so absorbed hydrogen escapes before it cracks them.
Hydrogen embrittlement
Delayed brittle cracking of hard steel fasteners caused by hydrogen absorbed from plating, cleaning or corrosion.
Zinc flake
A baked-on coating of zinc and aluminum flakes in a binder, giving high corrosion resistance without plating hydrogen.
Class 3A/3B
The tightest standard inch thread fit, with no allowance on the external thread, used for precision hardware.