I've had a similar experience with a pair of strap-loop Record pedals - left them a few days partially submerged in some dish washing liquid (Dawn Ultra) and the aluminum came out black where they were submerged. I took Simichrome to them... helped remove the black, but they're now two-toned, one section being more of a gray color.
I won't be using dish soap to soak aluminum parts anymore.
Aldo Ross Middletown, Ohio
----- Original Message Follows -----
From: "Tom Sanders" <tsan7759142@sbcglobal.net>
To: <classicrendezvous@bikelist.org>
Subject: [CR]Horrible black stains on my brake calipers!
Date: Thu, 27 Jul 2006 10:14:39 -0400
> Yesterday evening I set a really filthy pair of old Record
> Calipers in a plastic container filled with hot water and
> a couple of household grease cutting detergents to soak.
> I checked them later and they were coming along just
> fine...so I thought. I figured that I would just leave
> them over night and finish them up in the morning.
> To my horror, this morning they had ugly black stains all
> over the aluminum arms and these stains are very
> persistent. They will come off (mostly ) with the>
application of some 0000 steel wool, but so does the
> anodizing beneath the stain.
> I suppose I could take all the anodizing off to produce an
> even finish (is there an easier way than Easy Off Oven
> Cleaner?) but I sure would like to figure out a way to
> make the black stain disappear. Anyone out there got any
> experience or suggestions for dealing with this problem?
> Tom Sanders
> Lansing, Mi USA