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Finding no aluminum sulphate in anodizing tank although I put it there

February 3, 2010

I have a 98 liter acid anodizing tank. I added about 600 grams of aluminum sulphate (pellets) into the tank. I mixed the tank, agitated the tank and let the aluminum dissolve to the best of my ability..

When I titrate I see NO ALUMINUM content..

Where is all this aluminum going? I am really puzzled on this one.

Please help.

Garrett P
Hobbyist - Tampa, Florida

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Hi Garrett,

It is difficult to help when you say nothing about the analytical method used. If you will tell us, then some suggestions as to how improve the method and find the "lost aluminium".

Remember that if you are using a standard method for anodising solution analysis, the aluminium that you have added will be on the limit of detection. Assuming that you used the normal .16H2O salt you will have added only about 0.6 g/l Al. The Al content of an anodising bath will commonly be 5 - 25 g/l and a resolution of 1 g/l is fine.

Harry Parkes
- Birmingham, UK
February 8, 2010