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

--
uk to net for response

On Sun, 30 Nov 2003 10:50:11 -0000, "panda" <sam.bixby@wolfreton.eril.uk> 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?

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?
>><BR><BR>

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" <ajames54@hotmail.com> wrote in message
news:cusjsvk3f3tjt10i10gg94jv455mtsukal@4ax.com...
> On Sun, 30 Nov 2003 10:50:11 -0000, "panda" <sam.bixby@wolfreton.eril.uk> 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

philcycles@aol.communged (Phil Brown) wrote in message
news:<20031130203101.12054.00000994@mb-m26.aol.com>...
> >
> >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