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-----Difference Between Type I and Type II anodize
Quickstart:
In the anodizing of aluminum the components are immersed into a tank of acidic solution and connected to the anodic (+) positive pole of a power supply. The current separates some of the water in the solution into positively charged hydrogen and negatively charged oxygen. The oxygen is attracted to the positively charged components and converts the skin of the aluminum to aluminum oxides.
Readers new to anodizing of aluminum may wish to view our "Intro to Aluminum Anodizing".
Q. I would like a detailed explanation of the difference in the end product when using Type I or Type II anodize on Aluminum plate. Any Help?
John Hart1998
Aluminum How-To
"Chromating - Anodizing - Hardcoating"
by Robert Probert
You'll love this book. Finishing.com has sold a thousand copies without a return request 🙂
A. Type I, (chromic acid) is used for parts:
- having riveted or welded joints, or recesses within which is difficult to rinse properly
- which have total dimensional tolerances of from 0.0003" to less than 0.0005"
- where machining after anodizing is not desirable
- with less than 5% copper, no die castings shall be treated by this process.
Type II, (sulfuric acid) is used for parts:
- where coloring and decorative purposes are important
- which require hardness and resistance to abrasion
- on airplanes its use is restricted to parts not subject to stress and not containing recesses in which the anodizing solution might be retained.
Also see MIL-A-8625 / MIL-PRF-8625 [⇦ this spec on DLA].
Tom Pullizzi
Falls Township, Pennsylvania
Q. What base is anodizing dye. Is it oil or water and can I buy it in small amounts? What is the price?
Billy Doyle- Grand Prairie Texas us
2000
A. It is water based, Billy. You may be able to buy RIT dye ⇦ on eBay or Rit Dye [affil link] in small amounts for a few dollars if your needs are non-rigorous, but purpose-designed dyes for anodizing are probably a bit more more expensive. Please see "Seeking Anodizing Dye" for sources.
Good luck.
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