Maybe the spots are visible because of imbedded black compound, but why are there surface irregularities that the compond resides in? With the stuff I've worked on, posts in particular (I've never buffed cranks) it is pretty clear that the black bits, whether voids or pockets of oxide, do penetrate below the surface. I actually doubt it is residual compond because no solvent will rinse the color out. Also, by "pockets" I don't mean that the metal was like this as originally forged. While I agree that Campy probably didn't use contaminated alloy, at least not routinely, I do think that this is a corrosion pattern typical of whatever metal they make some of their parts from.
With three out five sentences ending in prepositions... Tom Dalton Brandon Ives <monkeylad@mac.com> wrote: Tom, I wonder if maybe the specks are bits of the original polishing compound imbedded during the transformation from standard to "Mexico" cranks. If you're sure it's not corrosion and you can't polish them out I can think of this as the only option. I don't think Campagnolo would have sent out any cranks that had contamination in the aluminum, so I don't see that as an option. I've always wanted some Mexico cranks even if that had little black specks. good luck, Brandon"monkeyman"Ives Captaining an office chair in Santa Barbara, Calif.
On Tuesday, 11, 2002, at 09:28AM, Eric Elman wrote:
>Tom, Thanks for the reply (below). The black marks in my crankset are not
>pits (small voids from corrosion), only speckled discoloration. I am
>familiar with how aluminium can corrode leaving a rough finish but that is
>not the case here. I have worked with aluminium parts on automobiles and as
>a fan and owner or Peugeot PX10's, the Stronglight 93 crankset and Mafac
>brakes are two examples of unanodized parts which are quite easy to keep
>looking good; I've never seen black specks these or in other aluminium parts
>but another lost member emailed me saying that his Campagnolo Mexico'd
>crankset has the same discoloration in it too. So, while I agree that
>corroded aluminium is very difficult to make good again, I believe these
>speckled cranks have some other problem. Any other thoughts?
>
>Eric Elman
>Somers, CT
>
>----- Original Message -----
>From: "Tom Dalton"
>To:
>Sent: Tuesday, June 11, 2002 9:44 AM
>Subject: [CR]Campagnolo "Mexico" Cranks, care and feeding
>
>
>>
>> The black speckles are pitting and are typical of un-anodized aluminum
>bike parts. On SR/NR stuff these parts include the shifters, ft der,
>clamps, pedal bodies, hub shells, and seat posts. Rear hubs and 'posts are
>particularly troublsome since they tend to see the most sweat from the
>rider. I'm certain that unanodized cranks would be a real nightmare to keep
>looking good. My experience is that pits are very difficult to remove.
>They are much deeper than you might expect. I've had posts that I sanded
>down, starting with coarse (!) emery cloth and moving to finer grits, then
>Scotchbrite pads and 0000 steel wool, finally finishing with Flitz polish.
>After all that, many of the pits remained. I'd say learn to live with the
>pits, and keep them in check by wiping down the cranks after each ride. A
>mild ammonia solution (Windex) is helpful, I think because of some ion
>exchange process.
>> Tom Dalton Bethlehem, PA
>
>> Eric Elman wrote: > 6. Lastly, my set is all polished
>aluminium but despite how much I polish
>> and buff them they have darker "stains/speckles" about the size of crushed
>> pepper in them that will not come out. The stains are only noticable when
>> you look closely but are there none the less - any ideas on the cause and
>> any possible way to eliminate these dark marks?
>
>
>
>_______________________________________________
>
>
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