The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Switching from anodized finish to Iridite

I am an electrical engineer at a small company that doesn't have anyone with knowledge about metal finishing. We are trying to make changes to an aluminum extrusion that is used to build our systems. The extrusion is presently being anodized blue. We are running into grounding problems and need to change the finishing process so at least part of the extrusion is conductive. The shop that we are dealing with is suggesting we switch to a blue Iridite process. I know that anodizing is more durable than Iridite. Is Iridite an acceptable finish for a large cosmetic surface? The other option would be to Iridite, mask, and anodize but this would be much more time consuming.

Thanks

John Monteiro
engineering - Bellingham, Massachusetts
February 24, 2010

---

Hi, John. Iridite is a Macdermid trade name, and covers a number of different chromate conversion coating processes, so it can be a bit vague to talk about. But traditional chromate conversion coating processes leave hexavalent chromium on the surface, which will probably be unacceptable for any components in the near future.

You will probably want to go to a trivalent chromate or non-chromate process.

Beauty is in the eye of the beholder, but chromate conversion coating is no match for anodizing. If aesthetics are important, I think you'll need to go with your "other option".

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
February 24, 2010

---

February 25, 2010

Plan c would be to use external star washers which will break thru the anodizing when tightened.
Plan d would be to remove the anodizing in the required spot with something like a Dremel ⇦ this on eBay or Amazon [affil links] tool with a stone, or burr or wheel.
If none of this will work, then you are at plan b.

James Watts
- Navarre, Florida