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Anodized Aluminum colored blacklytically and hot sealed

I am experiencing discoloration on anodized aluminum when IPA is applied as a cleaning agent. The article has a 20 microns anodize thickness and hot sealed using Top Seal DX-500. My question is what is causing this problem? The Anodizer claimed that the root cause is inadequate sealing temperature. We are trying to duplicate the problem by experiment but failed.

Teddy Mercado
Process Engineer - Manila, Philippines
March 27, 2008

Discoloration on anodization, according to my experience, is generally caused by:
1. jitterbug finish. The texture is not uniform
2. pretreatment. When pretreating, you should spray rinse with DI-water of minimum resistivity of 4 M Ohm-cm to avoid remain acid.
3. You didn't show your sealing temperature, so ...

Kearny Gong
- Shanghai, China
March 29, 2008

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