F.A.O Nigel Donnelly

[GeorgiePorgie]

Nigel,

I must take serious issue with the advice on page 91 (used car buyer) & specifically the advice " Take the wheels off at home and coat the mounting surfaces with copper grease" this is the WORST thing that you could do! if you put copper in contact with aluminium (or any aluminium alloy) and then that contact is subjected to any salt water solution (road salt & water mixted) YOU WILL induce SERIOUS corrosion, it's called galvanitic reaction, what will result is the rapid corrosion and deteteriation to the extent that the alloys will disintergrate at the point of contact!

By all means take off the alloys & grease the mounting point (but grease it very spariningly) with any molyblendum type grease, but NEVER copper grease.

The alloys do corrode as you mention and then they corrosion weld to the hubs making it almost impossble to remove an affected wheel at the roadside!

 

[C_374479958]

Hi George, I understand where you are coming from, but I think you are a little OTT.

High temperature anti-seize lubricant. Copper Paste is a soft, copper-coloured paste, based on micronised copper powder and synergistic anti-oxydant, anti-corrosion and anti-wear additives suspended in a premium grade stable oil. It is an effective anti-seize formulation, preventing metal-to-metal contact, seizing, galling, and fretting corrosion.Is not affected by acids or salt

and is not washed away by water.

And because of its anti-oxydant properties will not be a problem on copper or aluminium wheels.

 

[GeorgiePorgie]

Hi C,

I understand what you are saying but nevertheless copperslip grease in contact with aluminium or an aluminim alloy and any other metal higher up in the galvanitic scale in a salt water solution (doesn't have to be a complete solution just the presence of salt and dampness combined will suffice)WILL cause galvanitic reaction & aluminium being lower down the galvanitic scale than iron or steel will become the sacrificial anode!

In marine applications, copper in an epoxy medium (used as a long term antifoul agent to prevent marine growth on the hull of a boat or ship)is expressly forbidden for use on aluminium hulls, plus copperslip is a no no for a lubricant on any outboard engine or outdrive for the reasons previously stated.

After 40+ years in the motor trade I have seen the results of people using copperslip as the "lubricating" agent to prevent alloy wheels getting stuck on the cast iron wheel hubs, & its not a pretty sight, plus its expensive to rectify (you have to throw away the affected alloy wheel & purchase a new one as the damage is irrepairable.

I therefore stand by my original post.

 

[ValA.]

HonestJohn, (Motoring Correspondent) in this Saturday's telegraph, actually recommends Copper Grease for lubrication between the alloy wheel and the iron hub, in response to a query from someone about sticking wheels.

 

[GeorgiePorgie]

Val A,

With all due respect to Honest John, in this respect he's wrong!

Early Volvo 740 estate tailgates used to corrode around the numberpate lamp fixings, why? because the tailgate was aluminium & the copper earth return wire for the lamp was connected to the tailgate in that area.

Result, Volvo changed numerous tailgates under warranty & redesigned the earth mounting point (made an insulating gasket to isolate the copper wire from the tailgate.

Copperslip is brilliant in all other respects but for this type of application its a no no!

 

[Lord Braykewynde]

Perhaps Honest John ain't so honest and he's got his money invested in Beijing Acme Alloys.

Lutz is staying quiet on this one, I bet he's Googling it ... heh! heh! heh!

 

[machighlander]

no worries, sproket will be in with a link.

 

[GeorgiePorgie]

Just to explain galvanitic Reaction, the following extract is from the U.S. General Services Administration

Historic Preservation Technical Procedures

Corrosion:

All metals have a property called nobility. It is a measure of a metal's resistance to corrosion when in contact with another metal. A greater relative difference in nobility between the two metals in contact indicates a greater corrosion potential.

Table 1.1.4 ranks the most common metals used in construction in increasing nobility, called the galvanic number.

Table 1.1.4 - The Nobility of Common Metals

1. Aluminum

2. Zinc

3. Steel

4. Iron

5. Stainless Steel - Active

6. Tin

7. Lead

8. Copper

9. Stainless Steel - Passive

Custom Search For This 3000+ Page Website

When dissimilar metals are in contact with one another in the presence of an electrolyte, galvanic action occurs, resulting in the deterioration of the metal with the lower galvanic number. The electrolyte may be rain water running from one surface to another, or moisture from the air containing enough acid to cause it to act as an electrolyte.

Since copper has one of the highest galvanic numbers or nobility of the active metals, *it will not be harmed by contact with any of them. It will, however, cause corrosion of the other metals if in direct contact. The solution is to prevent such direct contact with the use of separating materials, such as specific paints or gaskets.

It is not necessary to isolate copper from lead, tin or stainless steel under most circumstances. The principal metals of concern in terms of direct contact are aluminum and zinc.

If paints or coatings are used for isolation, they must be compatible with both metals. Bituminous or zinc chromate primers can be used between copper and aluminum. Either of these or a red lead primer can be effective in separating copper from iron and other ferrous metals.

Taping or gasketing with nonabsorptive materials or sealants are effective methods of separating copper from all other metals. In areas with severe exposure, lead or similar gasketing materials should be used, except between copper and aluminum.

Regardless of the method used to separate the metals, wash from copper surfaces should be prevented from draining onto exposed aluminum. Traces of copper salts in the wash may accelerate corrosion of the aluminum.

 

[C_374479958]

Obviously no one believes my blog!!

 

[machighlander]

hi c, i belive ye mate. my bike has every stud and fastener taken off and coated with this stuff, its a godsend when coming to undo them at a later date for servicing, repairs etc.

also, it covers the ally and stainless steel ones, brill stuff.

 

[Sproket]

Now for you science lesson

 

[gary]

While I understand what is being said, it flies in the face of what happens in use?

I use copper slip all the time to stop corrosion between either stainless or zinc plated screws and cast aluminium, I've recently had a job back after several years and said screws unscrewed like new.

I would suggest the reason is the fact aluminium readily corrodes in air, this corrosion forms an instant protection to the aluminium underneath and either prevents or massively reduces further corrosion.

The point being is the corrosion is a extremely robust protection layer, anyone who has tried welding aluminium without removing the layer will testify to that!

Once vigorously removed, it will generally reform inside 3 hours!

I wonder then if copper is capable of attacking this layer? if not then it would explain what I see in practice?

One other thought is copper is a 'third' dissimilar in the joint, no longer simply the stronger attacking the weaker, but one stronger than both between?

Finally, copper slip actually containing copper is banned for health reasons in most manufacturing, there are alternates then that look like but are copper free.

 

[Sproket]

There are various antisieze compounds

anti sieze compounds

 

[TD42]

this thread has left me a little concerned. The Citroen C5 suffers from rear brake screech caused by corrosion build up between the rear Alli calipers & the cast suspension mount

The recommended fix on citroen forums is to remove the calipers

clean off the corrosion & coat the surface with copperslip & reassemble it.!!

 

[Sproket]

I would still use it, but if you want you could use this

Alumslip

 

[Entwood]

As I have been using copperslip in this fashion for many years on both car and 'van the opening post had me somewhat concerned.... so I have been doing some "asking" in various places..... and the consensus of asking analytical chemists, metallurgists and several design engineers was quite interesting ..... they all agreed with the OP in theory .. but .. BIG BUT .. also stated that the start of such a process would be so slow that it would probably take over 50 years before any visible effect would be noticeable, although at a microscopic level about 10 years might be sufficient. Several of those asked are keen DIY mechanics and said that they used copperslip as it decreased the ferrous/aluminium dissimilar metal corrosion effects.

At which point I was totaly lost. If it's ok for them it's OK for me !!!

 

[GeorgiePorgie]

Hi Nigel,

Thanks for your input, but I have to say that Alloys on cars & caravans are of the "magnesium alloy " type and as such are way down on the galvanitic scale in comparison to copper, & I have 40+ years of practical experience in the motor trade & the rate of corrosion through galvanitic reaction is much, much swifter than your "experts" suggest, in fact I've seen alloy wheels rendered useless in less than 2 years by the use of copperslip as a lubricant to prevent the alloy wheels "sticking" to the wheel hubs.

My advice has always been, & will always be DO NOT use copperslip, but use some other type of grease/lubricant.

I know that there are many variables that come into play, but at over

 

[Parksy]

Nigel who replied is not to be confused with Nigel Donnelly who signs his posts as Nigel the editor.

 

[forestgump]

we used o use it in petrol cemchical ie oil refineres aout 2000 ma be before was told that copper slip was baned dyue to its cancer contributes it chaged its formularng and we use it tody sorry but havin probs with inter net rrkmga

 

[Sproket]

Dean

have you been sniffing highlanders Iron brew .. :O(

 

[James3]

Don't be so rude Sprocket it is obvious to all that Dean has used some of this copper based goo on his keyboard

 

[James3]

Don't be so rude Sprocket it is obvious to all that Dean has used some of this copper based goo on his keyboard

Sorry Sproket I also used the stuff on my keyboard

 

[Sproket]

The Keys will be sticking on the keyboard, they do on mine, i thought about removing them and treating them with some Molyslip AS40/AS60 Anti-Scuff Paste.

Anti-scuff, bedding-in paste, gelled lubricating oil with a high proportion of MoS2. AS60 contains 60% of MoS2; AS40 contains 40% of MoS2 with graphite, rust and corrosion inhibitors.

it's cheaper to buy a new key board (

 

[machighlander]

Dean

have you been sniffing highlanders Iron brew .. :O(

hey, ya wee bochle, i read that.

 

[forestgump]

sproky not his iorn brew may be his sporen.