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Is lacquering allowed for zinc plating process?

September 25, 2011

Hi,
we are facing problem on black zinc plating color fade off.
our parts after black zinc plating, we use rubber to rub the surface and found that the black color fade off easily.
our zinc plater tell us that must use lacquer to cover it otherwise the black color will fade off.
but I checked ASTM B633, zinc plating does not include lacquering process.
what should I do?

Jason

Jason Chen
Engineering, Gaming, Music - Singapore

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Hi, Jason.

The customer is always right. If you are the customer, you get to decide if and how the plating shop can lacquer the parts. There is nothing inherently wrong in doing so, as long as the parts meet your needs. But it can be very wrong for a plating shop to take it upon themselves to add a lacquering step without the agreement of the customer, because the parts then might not meet the needs for conductivity or lubricity for example.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
September 26, 2011

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September 27, 2011

Lacquering for zinc plating process --
Recently we have a part requiring black zinc plating.
This item is used as a button, so that the color should not fade off easily.

Customer requirement: Zinc plating Black (no reference standard)
Our internal control: Zinc plating per ASTM B633
Test to be conducted: rubbing test per ASTM B571 for adhesion.
Adhesion test (burnish): using rubber to rub the black zinc plating surface for 15 times instead of using steel rod to rub the surface.
Outcome: color fades off easily after rubbing test by rubber.
Question:
1. Can we use rubber to conduct the adhesion test?
2. Can supplier apply lacquer over black zinc plating surface? If yes, do we need to inform our customer about the change?
3. Is the lacquering process a standard process for zinc plating?

Jason Chen
- Singapore