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Having problems hardcoating aluminum

2000

We are having problems hardcoating our aluminum. We can't get it to repeat.

My question is what is the best way to test the density of the acid tank and what should it read "avg".?

we are using a float hydrometer to test it now but have no idea what the reading should be. We are running it at 17 now. How to calibrate it for the temperature changes etc. I hope this makes sense. Any information on hardcoating aluminum will help

JOHN SMITH
- EAST CHINA MICH US

Specific gravity can be used decently to control a chromic acid anodize tank but can not be used on a hardcoat line. First the density changes with temperature, so you would have to wait till the tank was cold to test it or develop a fudge factor. Second, Anodizing is concerned with the amount of sulfuric acid in the tank. You gradually build up aluminum and other contaminants that contribute to the specific gravity and give a false high reading. Switch to wet lab testing. It is accurate and does not take a lot of time (a lot more than a SG reading tho). You can also do a test for the amount of aluminum which you should be controlling also. This is not as easy a test to get repeatable data on, and rarely will two different people get the same answer on, but it is relative. Control the aluminum and your life will be better.

James Watts
- Navarre, Florida
2000

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We might be able to help if you're willing to look at PVD approaches. To that end, What hard coating are you trying to apply, and what is the application?

Jim Treglio - scwineryreview.com
PVD Consultant & Wine Lover - San Diego,
California
2000

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In this context 'hardcoating' has a specific meaning: it's a synonym for hardcoat anodizing, Jim.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2000