copper slip and aluminuim frames with parts

I have a aluminuim frame i am building up. I was about to screw in the deore
rear derailleur and it struck me i wasnt sure if i should use copper slip,
since i think i read that steel, copper slip and aluminuim can react with
electolysis taking place. so should i use copper slip or grease?

many thanks

panda

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uk to net for response

sam- I have a aluminuim frame i am building up. I was about to screw in the
deore
rear derailleur and it struck me i wasnt sure if i should use copper slip,
since i think i read that steel, copper slip and aluminuim can react with
electolysis taking place. so should i use copper slip or grease? BRBR

Either, just not dry...

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

"ajames54" wrote in message
...
On Sun, 30 Nov 2003 10:50:11 -0000, "panda"
made this cogent remark :

I have a aluminuim frame i am building up. I was about to screw in the
deore
rear derailleur and it struck me i wasnt sure if i should use copper
slip,
since i think i read that steel, copper slip and aluminuim can react with
electolysis taking place. so should i use copper slip or grease?

many thanks

panda
Copper slip/copper grease or anti-seize are pretty much the same thing
and are a good idea when putting two dissimilar metals together...the
electrolysis (galvanic corrosion) will take place in any event the
copper acts as a sacrificial material to protect the other two...
that being said a barrier method like Teflon tape is often a better
answer in situations like the derailleur bolt that wont (ever?) be
moved after installation.
Finally since the part is unlikely to be moved often and has a
reasonably small surface area ...regular Grease will also be fine...


How's that for a non answer?

cheers. although i had made it completely UNclear i actually meant copper
slip or normal grease. but question answered anyway - thanks

panda

"ajames54" wrote:
Copper slip/copper grease or anti-seize are pretty much the same thing
and are a good idea when putting two dissimilar metals together...the
electrolysis (galvanic corrosion) will take place in any event the
copper acts as a sacrificial material to protect the other two...
that being said a barrier method like Teflon tape is often a better
answer in situations like the derailleur bolt that wont (ever?) be
moved after installation.
Copper is absolutely no sacrifice material since it is more inert than
any other metals on a bike. Copper grease will however prevent
seizure of the metal parts ("cold welding").

This has nothing to with corrosion. Copper grease consist mostly
of grease and it is the grease that limits corrosion by hindering
water to wet the surfaces.

Best regards
Erik Lindeberg

This has nothing to with corrosion. Copper grease consist mostly
of grease and it is the grease that limits corrosion by hindering
water to wet the surfaces.

Water doesn't have anything to do with it. Look up galvanic corrosion.
Phil Brown

unged (Phil Brown) wrote in message ...

This has nothing to with corrosion. Copper grease consist mostly
of grease and it is the grease that limits corrosion by hindering
water to wet the surfaces.

Water doesn't have anything to do with it. Look up galvanic corrosion.
Phil Brown

Dear Phil,

The first thing that came up suggests that
you need to explain further:

http://www.ocean.udel.edu/mas/masnotes/corrosion.html

Galvanic Corrosion

by Dr. Stephen C. Dexter
Professor of Applied Science and Marine Biology

Galvanic corrosion, often misnamed "electrolysis," is one common form
of corrosion in marine environments. It occurs when two (or more)
dissimilar metals are brought into electrical contact under water.

When a galvanic couple forms, one of the metals in the couple becomes
the anode and corrodes faster than it would all by itself, while the
other becomes the cathode and corrodes slower than it would alone.

Either (or both) metal in the couple may or may not corrode by itself
(themselves) in seawater. When contact with a dissimilar metal is
made, however, the self-corrosion rates will change: corrosion of the
anode will accelerate; corrosion of the cathode will decelerate or
even stop.

We can use the seawater Galvanic Series, shown in Table 1, to predict
which metal will become the anode and how rapidly it will corrode.

[it goes on for quite a while and the table seems
to indicate that water is rather important]

Carl Fogel