-----
How do you get color with Anodize and Alodine?
Quickstart:
Readers wanting a quick intro to anodizing of aluminum may wish to view our "Intro to Aluminum Anodizing (Anodic Oxidation of Aluminium)".
Quickstart:
Aluminum is often 'chromate conversion coated' as a corrosion resistant final finish or as a pretreatment for painting or powder coating. The process actually involves many steps, usually including alkaline cleaning, etching, deox/desmut, the chromate conversion step per se, and water rinses between each step.
MIL-C-5541 / MIL-DTL-5541 / MIL PRF-5541 is the most commonly cited spec. "Alodine" and "Iridite" are proprietary trade names of the suppliers of the process chemistry. In the USA "Chem film" is an often used slang term for the process.
Q. How do you get the color when a piece is anodized? Can you get color with Alodine? Seems I saw somewhere that one of these processes uses RIT dye ⇦ on eBay or Rit Dye [affil link]. Is that true? Thanks.
Chris VuxtonAircraft Hobbyist - Warrenton, Virginia
2003
A. Hi Chris,
Alodine is a Henkel trade name for MIL-C-5541 chromate conversion coating, which can be clear or gold-ish.
Anodizing is a different process and anodized parts can be dyed nearly any color, The dyes and the dyeing process can be a bit complex to get really right; but yes, a hobbyist can work with RIT dyes instead (although it is far better to use professional anodizing dyes).
The conventional sulfuric acid anodizing process does not find much application in aircraft for a number of reasons including loss of fatigue strength and the corrosiveness of the sulfuric acid. Please offer as much context as you can so we don't misunderstand and mislead you.
Good luck.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Ted can be retained for immediate
answers or long term project help
Q. I am using Alodine 1500 on my products with clear finish. Is there a way to get gold color/finish with Chrome III coatings? Please provide details on any dyes or materials available.
Thanks,
Sarah CrawfordPower electronics - US
2004
A. Hi Sarah,
I believe that some suppliers are offering dyes for the process but they reduce the corrosion resistance. As far as I know the TCP process developed by the Navy, accepted in MIL-C-5541, and licensed to many suppliers, does not allow dying. However, at least one supplier offers "thick film" trivalent chromating as opposed to the usual "thin film", and I think this is gold colored, but am very open to correction.
Luck & Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Ted can be retained for immediate
answers or long term project help
Q, A, or Comment on THIS thread -or- Start a NEW Thread