On Sat, 02 Jul 2016 07:59:40 +0200, Emanuel Berg
wrote:

AMuzi writes:

1. Maybe galvanic corrosion with the nipple,
maybe with a steel rim insert.
But corrosion nonetheless.

If it is "galvanic corrosion", is the corrosion
in or due to the zinc coating? Because if it
is, that is ironic as it is put there to
protect from rust!

Have a look at
http://www.corrosion-doctors.org/Def...nic-series.htm
which gives you an inkling of what is the cause.

The further apart two metals are on the chart the greater the
potential for corrosion. But remember, there must be an electrolyte
for the metals to corrode.

But I suggest the real question may be, how long have these things
been in use"? Something that had been in use for, say 10 years, and
has slight evidence of corrosion will likely last another ten years,

2. Well, the wheelbuilder's reasons may
include strength, cost or 'because we have
brass nipples'. As with #1 above, here we
are, it's corroded for whatever reason.
Your problem is more whether to ignore it,
clean it or replace it I think.

OK, so I know LISP is from the 50s, UNIX from
the 60s-70s, C++ the 80s, and Linux the 90s!
Does that make me a better programmer?
If I look at a piece of code, I can't say
a single line was improved by that knowledge.
But knowing it, I feel more appreciative of
what I'm doing, more confident and relaxed - it
is more pleasant to do...

It is, or could be, the same with rims.
If I true 10 rims, and can tell a story about
9, it won't feel like truing 10, it'll feel
like truing 2 - one plain, and one while
listening to a story!

Also, this kind of "facts for fans" are often
useful when you don't expect them to be.
Did you ever notice, when you learn something
new, the next day or something you hear to guys
on the street talk about it! Why didn't you
hear it all your life? Probably you did but
because it didn't make sense there was no
socket in your brain where it could land... Now
it does and it feels good

As for the actual rim, I think I cleaned that
and put it somewhere when I wrote the
original post!

This interesting excursion aside (or forked),
is there any tricks to cleaning it with
conventional tools? I got most of it away with
a wire brush but I heard that would damage the
aluminum and/or (?) the coating!
Getting chemicals isn't anything I consider at
the moment because it is just normal rim, of
which I have countless, and this is the first
time I saw it - unless the chemicals are
inexpensive in which case I'll get them if
I see them...

You might try vinegar? Or even coca-cola :-) I believe that they have
both been used to remove corrosion.
--
cheers,

John B.