The authoritative public forum
  for Metal Finishing since 1989
-----

Percentage of Hex Chromate

I have components on m assemblies that have a finish named: Alkaline Zinc Cobalt with yellow chromate. My question is: what percentage is hexavalent chromate of this finish? I'd appreciate your help.

Thank you.

Moises Perez
- El Paso, Texas
2003

---

There are some letters on line here, if you want to spend some time with the search engine, where the percentages of hex chrome in components were estimated, Moises. But the short answer is "too much". If the subject of hex chrome content has come up at all, you need to switch to a trivalent chrome or non-chrome finish.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

---

Some, since the yellow color is due to hexavalent chromium (unless dyed). Two suggestions for obtaining a quantitative answer: 1) Have your finisher ask the chemical vendor for the data, 2) Send parts to a laboratory for analysis for both total and hexavalent chromium. Send a typical part, and one each of the lightest and darkest yellow parts that are acceptable. Ask for results in milligrams/square meter.

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
2003