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Want to Hard Anodize in Colors

Hi, we are investigating to set up a hard anodizing line. We have previous experience in PAA before and most important aim is to upgrade our products with pretty cosmetic colors and harder surface to prevent scratching.

We know hard anodize is a different thing from general PAA, is anybody kind enough to tell me is there any method to keep the charming colors from PAA while having a hard surface not affecting the colors ? We appreciate if there's somebody to contact us for discussing this project. Thanks, Sammy

Sammy Shum
production manager - Hong Kong
2003

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I'm not sure if you misunderstand anodizing or I do. To me, PAA means phosphoric acid anodizing, a very thin and porous anodizing used for adhesive bonding for aircraft and similar applications. It may be possible to decoratively color it, but I wasn't familiar with that aspect.

The common decorative anodizing we see is sulfuric acid anodizing. While it is not as hard or thick as hard coat anodizing, it is very hard and scratch resistant. It is possible to color hardcoat anodizing, and it is sometimes done for military applications. But I don't think that's what you really want because it won't be nearly as attractive as conventional sulfuric acid anodizing.

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

I agree with Ted. There is another option that may be what you need. Try anodizing with sulfuric acid, but at 60F rather than 70F. Use about 20 volts. This will leave larger pores than true hard coat, but will have a thicker coating with slightly smaller pores than conventional anodizing. You may have to play around with the dye steps and you may not have to go to 60F to satisfy your needs.

James Watts
- Navarre, Florida
2003

The suggestion of doing anodizing at 60 f is a good one and the dyes can be impregnated at 60-70C for better adhesion and then sealed to increase weather proofing properties.

Harsh Khatau
anodizing colors ,pre-treatment & post treatment chemicals - Bombay, Mumbai, India
2003