Summary for rohs compliant black zinc Discussion
RoHS compliant black zinc is the focus of this thread, where Edwin Blackwelder asks how to get the same bright black appearance as hexavalent black zinc using trivalent chromate. The reply from eBay or Trent Kaufman says the industry was still divided on whether truly bright blacks were achievable: some suppliers at AESF meetings were explaining why good bright blacks were not yet available in trivalent chromate, while others were advertising complete success. The practical takeaway is cautious rather than prescriptive: there does not appear to be a reliable cookbook process in the discussion, and the answerer suggests the truth is likely somewhere between the competing claims. In other words, achieving a bright black finish with RoHS-compliant trivalent systems may be possible in some cases, but the thread does not provide a proven formula or guarantee.
We are moving towards RoHS compliant (trivalent) Black Zinc. How do we achieve the bright black of the hexavalent Black?
Edwin Blackwelder
metal finishing – Altamonte Springs, Florida, USA
2006
Some suppliers on the AESF meeting circuit are explaining why good bright blacks are not yet available in trivalent chromate, Edwin. Other suppliers are prominently advertising total success. Usually the truth is somewhere in between; but I doubt that anyone can give you cookbook instructions to achieve what major suppliers admit that they haven’t been able to do.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
2006
Cheat. Oh I mean use a black top coat aka black lacquer over trivalent black/non chromate black. Actually the final use and corrosion requirement are instrumental in deciding what to do. Despite what may say, the technology to CONSISTENTLY produce a bright black in a cost effective manner from a trivalent product, is not presently available.
Gene Packman
– Great Neck, New York
2006
Dear Sir,
I wanted to know whether Zn- Black trivalent plating is yet established or not if yes, what is recommended process.
Amarnath Mallick
– Noida
2006
Trivalent Black Zinc (Color Problem)
Q. Hello,
We are currently acid zinc plating some parts with a thickness around 8 to 12 micron and then passivate them with Pavco’s “HyproBlack” and then we apply a sealer.
We can achieve a greyish almost black color, but customer wants a jet black glossy color appearance.
How can I achieve that? Do I need a black topcoat?
Diego Mora
Buyer – Tijuana, Mexico
September 23, 2019
A. I use the hyproblack 3000 and it is jet black if everything is up to snuff. Had an iridescence problem once — it was a contaminated sealer.
Make a new batch in a beaker [beakers on
eBay
or
Amazon [affil link] of chromate and sealer and see what it looks like. My guess is (if there is enough chromate) you are low on part B or you have sealer issues.
But mine is over alkaline zinc. This may not apply most likely.
I use an Atotech Tridur process on acid chloride that is jet black.
Trent Kaufman
electroplater – Galva, Illinois
October 7, 2019
Thanks for your feedback, I will try to make an alkaline zinc solution, I might have better results.
Diego Guerrero [returning]
International Manucturing & Finishing Co. – Tijuana, Mexico
October 14, 2019
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