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Change in dye color of anodizing from black to blue after cleaning with IPA soln
I am a manufacturer of heat sinks & recently I face problem in few heat sinks at my customers end.
Problem : When my heat sinks cleaned in IPA solution few of them turns blue from black, We did not find any reason why it happened so. When we check the lot at our end we are not getting these results. If you have answer please let me know.
Proprietor of an organisation - India
December 29, 2010
The greatest probability is that the failed items were not sealed properly. They may have been sealed, just not properly, as evidenced by the fact that others do not fail.
Prolonged exposure to UV light, sun or fluorescent, will expedite any failure.
- Navarre, Florida
December 29, 2010
Respected Sir,
I wanted to know about the solution for problem which we faced at our firm recently. Prbm. is-
Black anodizing on aluminum Heat sinks shows blue color patches (not continually blue) after cleaning with IPA solution. We are using dark green base black color for dying. We checked all pieces due to rejection but only 4-6 nos. show this type of rejection.
Can any environment /solution affect color?
Please help me out if you have solution for this.
Regards,
Quality Assurance Incharge - India
January 1, 2011
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Ed. note: Looks like the boss got here first, Shital :-)
January 4, 2011
Sealing of anodized aluminum in natural finish/color is in cold sealing solution.
Sealing of black colored anodized parts is with application of oil (Palmolein)/ mineral oil.
Can this process of sealing is correct for aluminium heat sink?
Quality Assurance Incharge - India
January 4, 2011
Hi, Shital. I don't want to go so far as to say your sealing process is "wrong", but I'd say it's not what most people envision or would mean by "sealing". Most people think of sealing as closing the pores in the anodized coating by swelling the coating with boiling water or a nickel-bearing solution. As an experiment you might steam seal a black part (hang it above boiling water with a cover on your beaker or tank) and tell us what happens to your dye when you seal it and what happens when you clean it with IPA. Good luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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