In article ,
Jim Adney wrote:

On Sat, 21 Aug 2004 04:49:04 GMT Isaac Wingfield
wrote:

Crocus cloth is explicitly recommended for cleaning motor commutators,
so it should be fine -- actually, it's *very* fine 8^}

Yes, I agree, it's very fine. As long as it doesn't leave anything
behind it should be fine.

Some abrasives are insulators, and some are conductors; carborundum is a
conductor, for example. If I need a bit more "aggression" than crocus
cloth provides, I use a 600 grit carborundum "wet or dry" paper; the
grit is very solidly attached. A file, even a fine one, will remove a
lot more material than an abrasive.

I really don't think carborundum is a conductor. Can you find support
for this statement anywhere?

I was speaking from a memory of having used carborundum power resistors
years ago in FM broadcast transmitters; they were small for their power
rating because they could operate at a very high temperature without
much resistance change.

I found one mention of 1000 ohm-cm. at 1000 degrees C.

Here's an interesting URL I ran across:

http://home.luna.nl/~arjan-muil/radio/carborundum.html

Isaac