zinc plate ASTM - B 633 type 2

[privaate]

Hi
This is PVK Raju
I would like to know the Zinc plated parts acceptance criteria
Recently we have received parts from our supplier after Zinc plated as per ASTM-B-633 SC2, Type2 on that we have found visual appearance, like colour shade variation
Please suggest how to justify the color shade variation
Thanks in advance
Regards,
P V K Raju

 

[chez311]

PVK Raju,

The appearance you are referring to is commonly called the "patina". This can vary a surprising amount depending on the exact bath chemistry during that particular run but I believe typically has very little effect on the function of the coating - unless there are other abnormalities than just some variation in this patina. I am not aware of a standard for acceptable color variation of the patina, if this variation is unacceptable to you as the customer for aesthetic reasons I would suggest either developing an internal standard or at the very least specifying it somehow on the part print.

 

[privaate]

Hi
Thanks for immediate response
Still I am waiting more suggestions from others
If required I will share photos color shade variations
Pleae suggest
Thanks in advance
Regards
PVKRaju

 

[chez311]

You are more than welcome to post pictures of your parts, but I don't think my answer will change much.

You are also more than welcome to await additional input, however I wouldn't hold your breath - this doesn't seem to be a very active sub-forum. Perhaps you could post it over in

https://www.eng-tips.com/threadminder.cfm?pid=332

(paint and coatings engineering).