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How to spec zinc plating with trivalent iridescent yellow chromate
Q. We are used to working with hexavalent zinc yellow coatings such as A2C according to ISO 4042
[affil link] in our products and right now, due to customer requirements, we have to change to a trivalent coating.
We have a proposal to use a trivalent zinc plated with a slightly yellow iridescent colouration and the question is: Which code following some international standards such as ISO or DIN we could use to explain that coating?
Would the code Fe/Zn5/Cn/T0 according to DIN 50979
[affil link] be suitable for that slightly yellow iridescent zinc plating?
On the other hand, is there any other zinc plate and code which could fit better for a A2C zinc plated free of Cr6+?
Product designer - Barcelona, Spain
April 8, 2011
A. I know this is an old topic, but here's the info.
For zinc trivalent plating we use the spec:
ASTM B633
[affil link]
-13 Type V
- Granby, QC, Canada
January 20, 2014
A. ASTM B633
[affil link]
is for general zinc plating whereas ISO 4042
[affil link] is for electroplating of fasteners. ASTM F1941/F1941M-16
[affil link] would be appropriate as it is designed for zinc plating on fasteners.
The expected corrosion values between the two standards may vary as the IISO 4042
[affil link] and the ASTM F1941/F1941M-16
[affil link] in front of me have different expectations for white / red rust.
Sorry for bringing up an old topic, just wanted to make sure that the correct references are used for future readers.
- Buffalo Grove, Illinois
January 7, 2016
Thanks for the update, Erick!
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
January 2016
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