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Galvanic Compatibility of Aluminum and Copper

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Q. I am restoring a vintage Airstream travel trailer. It has an interior (and exterior) aluminum skin. I am thinking of installing wood paneling over the interior skin, and using copper pop rivets (strictly for aesthetics), to fasten the paneling to the aluminum skin. Interior moisture is passionately mitigated, but is a realistic possibility.

Will using copper rivets in this application produce a significant degradation of the aluminum skin ?

Steve adams
Hobbyist - Anchorage, Alaska
April 2, 2023

Black aluminum pop rivets

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A. Hi Steve. Pop rivets with copper heads and aluminum cores are sold, so some vendors think it's okay, and your installation location is relatively non-corrosive, so you could certainly take a chance.

On the other hand, there is essentially no galvanic couple that is worse than copper and aluminum, and if it was me, I'd look for copper colored all-aluminum rivets, and if I couldn't find them I might talk myself into black :-) Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey

⇩ Related postings, oldest first ⇩

Q. We would like to know the galvanic effect when we have a bolted joint Aluminum-copper, maybe there is a table experience or calculated values data.

Thanks for your help.

Gonzalo Ramirez
- Mexico city, Mexico

A. Aluminum will be very susceptible to galvanic corrosion in contact with copper, assuming that the two metals are also in contact with a common electrolyte (such as water with some ionic content.) Almost any text or handbook on corrosion will have galvanic series table. The farther two metals or alloys are separated on the table, faster the corrosion of the less noble of the two will be when they are in contact.

larry hanke
Larry Hanke
Minneapolis, Minnesota

A. Just additional note - Tin plate the copper bolts or other copper parts this will help stop or slow the galvanic attack.

Chris Snyder
plater - Charlotte, North Carolina

A. Also look into getting your copper busbar with a silver coating factory applied. This will improve bolted joints by reducing the resistance, and resists corrosion. Also, since it turns reddish black copper to a nice uniform grey, it blends nicely with the natural aluminum color. "Silver Flash" coatings are very thin, so additional cost runs only pennies more, per foot than plain busbar.

W. Carl Erickson
- Rome, New York

Q. I am also thinking about placing copper and aluminum in contact, this time in an antenna installation. Every comment above I can relate to and understand until W. Carl Erickson's about silver.

The only galvanic tables I can find relate to corrosion in seawater, but they still rank metals from most anodic to most cathodic. For example:

On that page, the author lists some design rules, including the need to have a low C/A Ratio (corollary IV). Therefore, tin/aluminum is better than copper/aluminum. But silver is at the far end of the cathodic spectrum, and by this logic making silver/aluminum very undesirable. Other sources say silver/gold/graphite are very noble. What does this mean for corrosion of the poor little anodes?

Also, electrical conduction is optional for me. Would conformal coating of the copper board, or anodization of the aluminum part, be better?

Mark Nelson
- Melbourne, Florida

A. Take a look at this link to see the galvanic series. There appears to be -.50 volt difference between copper & aluminum using a standard hydrogen electrode.

Despite all the responses here. Aluminum/copper corrosion is quite complex. Why? Because aluminum has an oxide on the surface and the oxide stability determines its performance. Galvanic series does not always predict the reaction in absolute terms since we would need to take into effect the area of the 2 metals. Chloride & copper can cause pitting in aluminum. Finally a table of corrosion rates is specific to an area. In Mexico, pollution is highest in the world. SO4, CO2, Cl-, F-2 can easily form acids with moisture and create corrosion. Atmospheric corrosion varies from place to place.

Kam Dianatkhah
- Dallas, Texas

Q. Hi! I am interested in the subject as I intend to connect copper pipe to aluminium part (threaded connection, nipple on aluminium with crox nut for copper pipe, or similar). Water flowing through the system is clean water (potable). Is there an issue with this joint? Is it going to help if I insert a section of PVC pipe in between?

All the heat transfer coils around the world are built with aluminium fins mechanically fixed onto a copper pipe, and they all work very happy for many years on the roofs and various environments, without corrosion. How come they do not rust?

Chris Moana
- Auckland, New Zealand
June 22, 2010

Q. I've been thinking of building a solar collector using the instruction found at but am concerned the copper tubing with aluminum snap on absorbers will be setting up the system for premature failure? Or is that not likely as there will be no fluids passing between these dissimilar metals?
Hope to hear back from someone with knowledge about this.


Kenneth Forrester
- Richmond, Virginia, USA
November 19, 2012

Q. In the presence of galvanic corrosion, can other dissimilar metals be drawn to the area of galvanic corrosion? Example: when aluminum and copper create a galvanic corrosion nodule, can soluble iron be drawn to that nodule?

Robert Aguirre
- Naperville, Illinois USA
March 1, 2013

A. Hi Robert. Your understanding of the phenomenon may be deeper than mine, and I may be misunderstanding the question, but I'd say "no".

Let's start by looking at a single metal unconnected to any other metal. It is made of atoms that have positively charged nucleuses (okay, "nuclei", Miss Crabapple) which are surrounded by electrons which balance the charges, and all is well. Then let's say these atoms become exposed to a corrosive media (an electron stealer). The corrosive media steals an electron. Now that atom is no longer an atom, but a positively charged ion in search of an electron; so it dissolves into the media in search of an electron to balance it. So, what actually causes corrosion is the loss of electrons from the metal.

Metals are electrically conductive, i.e., electrons can run through them from one spot to another just as they run through a wire. So if two different metals are mechanically connected in any fashion at all without an electrical insulator between them, electrons can run through them.

Now take a chunk of two different metals connected together and expose them to a corrosive media which is stealing electrons. The way galvanic protection/corrosion occurs is: when the nobler metal (the copper in this case) has an electron stolen from it by the corrosive solution, it has a greater affinity for electrons than the baser metal and immediately steals back an electron from the baser metal (aluminum in this case). The result is that the copper atom remains a balanced atom of metal, and the aluminum atom comes up short and corrodes into solution.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

Q. A contractor has attached short pieces of 25 mm copper to the aluminium corner posts by flattening one end and fixing with ZINC bolts. The posts were mistakenly cut short by one of his operatives. The copper will then extend into the sill/floor and will be filled with concrete.
Should I worry? The aluminium/copper joint itself will be covered with clip on PVC, and exposed to IRISH damp air only.

Patrick Mullin
- Omagh Tyrone Ireland
May 14, 2013

A. The zinc plating on the bolts will be the first to go.

Khozem Vahaanwala
Khozem Vahaanwala
Saify Ind
supporting advertiser
Bengaluru, Karnataka, India
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A. Hi Patrick. A photo would sure help me -- sorry, I'm lost :-)


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

Compatibility of copper wall caps on aluminum vent piping

Q. My homeowners association is very strict and requires copper for flashing and other exposures. I obviously have aluminium vent piping for my dryer and range vent hood. If I put copper wall caps on these pipes am I asking for trouble or does it matter?

Bryan Ellis
- Chesapeake Virginia
May 12, 2014

A. Hi Bryan. Theoretically, the aluminum will galvanically corrode near the area where it's connected to copper when it's wet. But it's not a critical application like on an airplane, and rainwater is not highly conductive. As a practical matter I just wouldn't worry about it.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

Q. I have a related question on this topic. We are investigating the use of copper in an appliance application. I have a thick copper plate (99.9% pure) and put an aluminum pan on it. When I heated the plate (gas flame below), we got a flaky black oxidation on the copper surface where the two metals touched. It also took longer for the water to boil (vs. a typical cast-iron plate). However, the copper should have higher thermal conductivity. So how could it have been slower to boil? We're thinking we had a galvanic response between the two and the black oxidation acted like an insulator and slowed the heat transfer. Does this sound plausible? Is there a coating or plating we could use on the copper to prevent this oxidation layer from forming? Many pots and pans are aluminum, or anodized aluminum, so just using SS pots is not a good enough solution.

Hans Wenzel
- Fullerton, California USA
June 16, 2014

A. Hi Hans. No. it doesn't sound plausible to me. Galvanic corrosion involves two electrical paths: a metallic path which electrons can flow through, and an ionic path (liquid) through which ions can flow. If one path doesn't exist (in this case a liquid path), I don't think you can have galvanic corrosion.

Galvanic corrosion is certainly not the only possible kind of corrosion though.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey


Q. I'm interested in this subject because I'll be connecting two AA batteries through an Aluminum foil (aluminum conductive 3M tape) jumper -- do you think galvanic corrosion can be raised in this connection? It will be only 3 volts.

I'll appreciate your help

Carlos Villanueva
- Chihuahua, Mexico
August 12, 2014

A. Hi Carlos. Galvanic corrosion is not usually as issue in the favorable environment that electronic devices are usually in. I'm not really familiar with that conductive tape, but I believe that the adhesive is conductive, as bare aluminum would not serve properly as a contact surface of this type. What happens when the batteries need to be replaced if one end of them is taped together? (I think the contacts on both ends of the batteries should be nickel or electroless nickel plated rather than aluminum tape).


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

Q. I'm building a spot welder and I'm thinking about using aluminum bars to hold copper electrodes. Obviously, this has the potential for a galvanic reaction, but it will stay in my garage and will not get wet. Will a slow galvanic reaction be a problem? Will it affect the conductivity of the copper-aluminum junction? I'll be running close to 1000 amps through this, so good conductivity is critical.

Lee Ratliff
- McKinney, Texas, USA
August 15, 2014

"No-Ox-Id" Compound
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A. Hi Lee. You're probably right that galvanic corrosion per se won't be a problem in a dry environment -- but the surface of aluminum oxidizes to a high resistance film, and non-plated aluminum is rarely a satisfactory conductor for this reason. If the joint is assembled with a "No-Ox-Id" compound it will probably be okay though.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

Q. It seems contrary to galvanic corrosion, but if I put a Cu pan in the dishwasher with SS flatware, everything comes out fine, but if I include an Al pan, the Cu comes out black. Can you explain this?

David Denley
- Houston, Texas, USA
December 10, 2014

A. Hi David. I'm not sure that I understand what you are describing, but galvanic action requires a conductive metal path between the two metals. If the aluminum pan is not touching the copper pan, and neither is touching the flatware, then no galvanic corrosion is taking place. If two of those three metals are touching, but not the third, galvanic action may be occurring between the two, but not the third.

Aluminum pans don't belong in a dishwasher. The usual detergents are highly alkaline and readily attack the aluminum.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

Q. Hello. I would like to put a solar copper "ionizer" in a cedar wood fired hot tub. I wish not to add chemicals such as bromine, chlorine, etc., to the water, which will be changed about once a week. The "stove" is an aluminum box immersed in the fresh water. The metals would not be in direct contact. Should I worry about damaging my stove? Would placing a sacrificial zinc bolt protect the aluminum? Thanks!

Bruce Baird
- Watertown, New York, usa
April 28, 2015

A. Hi Bruce. There can be no galvanic corrosion if the parts aren't touching, but that doesn't necessarily mean that copper and aluminum can completely resist corrosion. Zinc anodes will not protect aluminum in fresh water -- you would need magnesium anodes.

Although I'm not really familiar with copper "ionizers", it sure sounds like they are designed to put copper ions into the water. That copper would try to plate out onto the aluminum, and it could be an issue (I know that copper dust is very corrosive to aluminum), but hopefully the magnesium anode will protect it. Good luck.


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey

Q. I don't know anything about all the technical stuff people are posting, but I am hoping to find out if it will be a problem to install my new gutter guards made of "mill finish aluminum" our our copper gutters. They also have a stainless steel mesh but don't think that would come in contact. The company said I could apply a coating on the aluminum but that sounds like a lot of extra work.
thank you!!

Lulu Cucuel
- Santa Cruz, California USA
November 13, 2015

A. Hi Lulu. Assuming you don't use salt on the roof, or spray mildew preventer or anything on it, so the only moisture is rain water, I doubt that it will be any problem. Galvanic corrosion requires a conductive liquid and rainwater is rather non-conductive. Further, gutter guards are not a critical application at all.


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey

Q. Hello,

I'm researching the effects of galvanic corrosion due to copper chips and dust imbedded in aluminum coils from high pressures in machining. I am trying to find cost effective ways to remove copper dust from the machine (steel) before introducing aluminum.

If that isn't a plausible solution, would it be better to plate the aluminum with a sacrificial metal to prevent pinholes in the coil? Would this significantly impact the heat transfer of the coil? If not what metal would you suggest to plate it with?



Nick Scott
- Grenada, Mississippi, USA
December 2, 2015

A. Hi. I don't really understand what you mean by "coils" or what heat transfer you're talking about. Keeping the dust away is probably the best solution, but you could copper or nickel plate the coils, or even electroless nickel plate them.


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey

Galvanized framing nails and copper siding

Q. Hello, my entire house is copper cladded with 4x2 sheets interlocking. We are building an addition and instead of removing copper, contractor nailed framing directly into copper sheets with hot dipped galvanized nails. Do I need to worry about corrosion and my addition falling apart? It's such a mass of copper around the framing nails, I was unsure how I felt about it. I see that hot dipped galv. is basically steel with a zinc coating. Let me know if picture of house would help

Brittany Kelly
- Rock Hill, South Carolina
September 8, 2016

A. Hi Brittany. As a homeowner myself, I wouldn't expect it to take much time to remove the siding; and the copper siding has good scrap value. So it does sound a little strange to me to leave the old copper siding in place rather than removing it. But I'm not a builder, and I suppose it's possible that he didn't think it was practical to attach the now loose end of the siding to the house if he cut it instead of just leaving the whole sheets attached.

Galvanic corrosion is an issue in wet environments, so if you told me he cut the sheets and nailed the edges with galvanized nails, I'd probably expect severe staining at the nail heads. But in what will now be dry interior framing, I don't think I'd expect corrosion of the nails.


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey

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