copper slip and aluminuim frames with parts

On Sun, 30 Nov 2003 10:50:11 -0000, "panda" <[email hidden]> made this cogent remark :

Quoted message said:

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?

Quoted message said:

Quoted message said:

<BR><BR>

Either, just not dry...

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 vecchios.comvecchios.comOpen ↗ "Ruote convenzionali costruite eccezionalmente bene"

"ajames54" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

On Sun, 30 Nov 2003 10:50:11 -0000, "panda" <[email hidden]> made this cogent
remark :

Quoted message said:

I have a aluminuim frame i am building up. I was about to screw in the

deore

Quoted message said:

Quoted message said:

rear derailleur and it struck me i wasnt sure if i should use copper

slip,

Quoted message said:

Quoted message said:

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 said:

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

[email hidden] (Phil Brown) wrote in message
news:<[email hidden]>...

Quoted message said:

Quoted message said:

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:

ocean.udel.educorrosion.htmlOpen ↗

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