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Cleaning aluminum

I have parts that I clean with water and soap then dry them they are clean and dry then we ship them to Texas and they have black grease finish on them.

Bob Hull
- Mason, Ohio
2005

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A couple possible causes and suggestions:

1. Contamination from the packaging (for example, see http://www.micromagazine.com/archive/98/10/graves.html). So-called "low-outgassing polyethylene" is an option available from several cleanroom film vendors.
2. Machining lubricants trapped in the pores of the surface. Investigate an alkaline soak degreaser/cleaner that has a mild etching effect on the aluminum surface. You might want to do a low temp. degrease, followed by a higher temp. mild etch.

Grant Kiehne
- Bloomfield, Connecticut, USA
2005