Parts returned for Plating too thin

A. Your plater should be able to produce a minimum thickness of 0.0003 inch gold. You don't say what specification is being sited on the drawing but Mil-G-45204 gives the following information: Type II is 99.0 gold purity, Grade A through D refers to deposit hardness, Class 00 through 6 refers to thickness (Class 4 is 0.0003 inch thick minimum). Also, unless the drawing specifies otherwise, only surfaces which can be touched by sphere 0.75 inch diameter need meet the minimum thickness.

A. Hi. My guess is that Shirley means to talk about zinc plating with a 'gold' colored chromate, perhaps ASTM B633, rather than gold plating. Regardless, Neil's point that it is customary for a minimum thickness specification to only apply to areas touchable by a 3/4" diameter ball remains a good one.

It should be relatively easy to increase the plating thickness somewhat, but the approximate 3:1 thickness ratio between the thickest plating on the part and the thinnest is not real surprising. And if you truly need .0003" minimum, it may be worthwhile to improve the racking, switch to a type of plating with more even throwing power, or consider auxiliary anodes -- because .0009" on the thick areas is probably more than you would reasonably want.

Good luck.

Regards,