Skin products affecting dyed anodizing?

Aluminum How-To
"Chromating - Anodizing - Hardcoating"
by Robert Probert

Also available in Spanish

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My guess is, that the shaving cream is somewhat alkaline, and more so than the anodizing, or rather sealing, can cope with. And therefore the dye can be removed over time, due to the pore no longer being sealed, and thus the dye and pore is exposed to the shaving cream. It should be fairly easy to test, either by exposing one of the parts to prolonged exposure to shaving cream (Different variants probably, along a wide price range), or measure the pH of shaving creams to see where they are on the scale, as anything over 9 is an issue.

Don't know whether you did the dye spot test on an area where the dye is now missing (i.e. an old part), or you tested on a fresh spot or on a new part.

Anodized parts are not great outside of a fairly neutral spectrum, so anything below 4-5ish and above 9 on the pH scale, is going to cause you trouble.

A. To begin with, if I were you I would attach pics of problem which you mentioned despite your good explanation of problem. In my opinion, there are two possible reasons regarding source of problem;

1). Poor sealing quality; insufficient sealing duration or sealing bath chemistry. Despite dye stain test result being good, but that won't mean everything is ok. Weight loss test is most important test for quality of sealing so weight loss test must be done. Also I advise cold sealing instead of hot one).

2). Anodizing layer (sealed) is resistant to only between ph 4-8.So may be sweat issue effected or trigger of sealing quality time over time.

Good luck...