Letter 5025

Staining on aluminum after sealing 

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Hello fellow anodizers.

I am a lab tech at a major company. I have been doing this for 17yrs and have seen alot of problems. we have 24 tanks. cleaner etch d-smut anodize color and seal of course all the rinse and di tanks needed.

my problem is we are having a staining problem. we use a cold seal nickle fluoride bath and follow it up with a hot seal@ approx.150 degrees it contains a small amount of a surfactant acetate I believe. the unusual thing is we pass dye stain, modified stain with nitric then dye and also the acid dissolution test. but if you take a piece of mat'l and put water on it, it will leave a ghost like stain. our alloy is 6063, is hardness a big factor? ours runs anywhere from 7 to 15. it seems like 12 or 13 works the best. i have the chemical vendors lookin. I'll take any info anybody has. also i may have some answers to other peoples problems.

brian vandivier
- fraklin,in johnson

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