We always think about rainwater , and sweat , getting down between the tubing and the seat-post , or between the tubing and the stem .
And I know I always think about "wash water" getting down in there .
Since I would NEVER use a harsh cleaner , I'd never really thought about what could possibly be in the very worst-case "wash water" .
I received a very nice , used-but-still-pretty-fresh , 1978 Proteus bicycle , not long ago .
The seller had a horribly hard time getting the seat-post out . I personally have never seen a Campagnolo Record seatpost as badly corroded as this one . I looks as if it is made from old , partially decayed , oyster shells . It is obviously no longer solid metal at all . It's made of many-many layers of horribly corroded aluminum . There is physically no way that it could possibly go back into the seat tube from which it emerged . The seat-post quite clearly "blossomed out" , and opened-up , after it was pulled out . What a mess .
The good news is that the aluminum sacrificed itself for the good of the seat tube . The steel looks great . Although , the patterns are clearly a match . So yes , I am sure that this post came out of this tube .
The stem was not too badly affected , somewhat , not much . Puzzling .
I had not thought about someone using some sort of caustic cleaning solution , or solutions .
Go to the auto parts store . Look at the various cleaners . They do indeed make a major big deal about either being safe for use on un-coated aluminum , or , NOT being safe and NOT to be used on aluminum .
Just never thought about that one before .
AND , what is available at car washes today , can be VERY dangerous to delicate finishes , and delicate metals . Stand down-wind of a modern car wash , while they are spraying their special "ultra-cleaner" or whatever they may call it . It does NOT smell like detergent and water . It smells much more like some kind of toxic paint remover .
The new "no touch" car washes use some seriously HARSH cleaners .
Bicycle shop people have always had to remind customers NEVER to use a car wash place , for cleaning their bicycles .
Now it's much more true than ever before .
Does anybody know what causing "pitting" of alloy parts? I've noticed this
pitting on the bases of Cinelli stems, and seatposts where they were
inserted. These are typically greased fittings that are really puzzling me.
I know certain detergents that are high alkali cleaners (high PH) are
caustic to soft metals, that maybe the previous person cleaned the bike with
some kind of cleaner that was corrosive. That is my only guess. I'm sure
you've all noticed this too. Please note that what I'm talking about is
"pitting" and not the typical scratches that take place. Anyway, I'd like
to be able to prevent such pitting from occuring in the future. Any advice
would be appreciated.