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Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Plating the inside of a gas tank
April 25, 2021
Q. Hello everyone, Im new to this and struggling.
I'm trying and failing to zinc plate the inside of my fuel tank to rust proof it. It's an old bike. Derusting is not a problem. Brown vinegar
⇦in bulk on
eBay
or
Amazon [affil links] did a good job the first time. Electrolysis worked better the second time. Preventing flash rust after rinsing out is a big problem.
Beyond that,Im working with homemade zinc electrolyte (salt, white vinegar and zinc. Brewed for 5 hrs +/- at 500 ma.)
I have many questions as to how to make this work. The first one is, is it possible to plate the inside of a tank? (I've been told that Faraday would say NO)
The second question is, What am I doing wrong? Obviously,I have to overcome the flash rust problem. I'm working on that but any suggestions would be welcome.
I've had good results doing nuts and bolts, small brackets, etc., but the tank is a different beast. I could use advice.
Thanks in advance.
- Amsterdam North Holland
⇩ Related postings, oldest first ⇩
2004
Q. I am repairing an old motorcycle, the gas tank is rusted on the inside. I can buy a kit to clean the inside, and apply a liquid that cures into a plastic. I would rather plate the inside with tin, or lead. I can use an old battery terminal, or a roll of solder for an anode . The inside of the tank will be the cathode. I don't know what to use for an electrolyte. If solder is used for an anode will the individual element with the lower number on the galvanic scale be the one that plates out onto the cathode, the solder, being an alloy?
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True Story , I sand blasted a brake drum , cast iron , and wanted to warm it up in my oven before spray painting it. Well, its a gas oven, and produces water vapor which flash rusted my freshly sandblasted part! I went down into the Basement , and dunked the brake drum into an acid solution that I previously used to De scale My tankless hot water heater ( copper tubes ). Much to my amazement, The brake drum became copper plated without a power source! I think Iron is lower than copper on the galvanic scale, if that had anything to do with it. Could you describe in layman's terms What happened? 3rd Question, some parts on my motorcycle are plated with a dark color I can only describe as Olive Drab- Almost Black. I need to know what this is called so when I talk to a plater, so I can ask them if they plate such a finish . |
Hobbyist - Old Bridge , New Jersey, USA
2004
A. Applying your liquid that plastic coats your tank is probably a better idea, Paul. There are many reasons it's not practical to copper plate the tank.
Yes, when you dissolve an alloy like solder, the more noble component metal usually plates out preferentially.
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In times that were less environmentally sensitive, scrap metal (like scrapped cars) used to be placed into streams, downstream of copper processing facilities, to "plate out" the dissolved copper as you've described. You are correct that copper is more noble than iron and will spontaneously plate out onto iron. Although all explanations are simplifications, you can think of it this way: copper is better at holding onto electrons than iron is, so positively charged ions of copper will grab electrons from the iron, thus reducing the copper ions to copper atoms, and thus oxidizing the iron atoms to positively charged iron ions. So an atom of iron dissolves and replaces the atom of copper in solution. Immersion plating like this is very limited in thickness because as soon as there is a coating of copper, the underlying iron can no longer dissolve so no more copper will be replaced by it. And one issue is that if the metal you immersion plate onto the steel is not pit-free and pore-free (and it probably won't be) will accelerate the corrosion of the steel. Just as zinc is used as a sacrificial anode to protect steel, steel is a sacrificial anode to anything that you can immersion deposit onto it :-( The parts that you describe are probably zinc plated or cadmium plated with an olive-drab chromate conversion coating. Yes, olive drab is the correct term. But please use the search engine to find threads about those copper immersion deposits and olive drab finishes and continue the discussion there. You're bringing up very interesting topics for discussion, but we have 60,000 threads about metal finishing, and unfortunately readers can't find stuff if it's scattered across threads on other topics -- especially because google 'de-indexes' threads which it considers duplicative, meaning that entire discussions (perhaps including this one) simply disappear from the search engines :-( |
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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A. Most likely the solution that plated your brake drum was ferric chloride ⇦this on eBay or Amazon [affil links] , with a large quantity of copper dissolved in it. When you add a chunk of steel or iron to it you create a weak electric charge, which bonds the copper to the iron (I've used this trick myself on some show knives, oxidized the copper blue with ammonia ⇦this on eBay or Amazon [affil links] afterward). Marc Banks- Elizabeth City, North Carolina 2004 A. That olive drab color you are looking at was initially black from the factory. I use black oxide to refinish those parts and it fades out to olive almost black after time. sharrod stonerestorer - mesa Arizona August 6, 2021 |
August 5, 2012
Q. I want to galvanize the interior of my fuel tank. I just finished an electrolysis Rust removal and now I want to Galvanize it.
I have a piece of zinc.
For rust removal I have a positive charge steel as the sacrificial anode and Negative charged the tank. It took 36 hours to do and is very clean.
Now to Galvanize I fill the tank with water and sodium carbonate
⇦this on
eBay or
Amazon]
solution. Then I need to attach the positive to the tank and negative to the zinc.
Is that correct?
Let run until a galvanized coat is uniform throughout the tank?
Thanks
Chet
- Monroe Virginia USA
A. Hi, Chester.
You seem to be talking about electroplating, not galvanizing. The tank (the cathode) remains attached to the negative for electroplating, and the zinc (the anode) is attached to the positive. Sodium carbonate is probably sufficiently alkaline to hold zinc in solution and thus allow electroplating in theory. But there is much more to successful electroplating than that, so I don't think you'll meet with success soon, if at all. I would strongly suggest that you practice on something else and see for yourself what you are up against, rather than ruining something that you have worked on so hard already. Best of luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
August 6, 2012
Q. Dear Sirs,
I have a question for you.
I have a rusty gas tank of a motorcycle. I thought it would be good solution, the first to take off the rust so it will perform electrolysis solution of sodium bicarbonate (300 g in 17 l of water) and iron bar (+) inside of tank and tank (-). And when I derust it to copper plate it. The simple question is HOW?
My wish is to protect the tank so that it does not rust again.
Best Regards
Radmilo
- Belgrade, Serija
October 5, 2013
A. An easier solution would be to use a tank sealer like "Gold Standard Tank Sealer" or one of the many others widely available. You'll find that and many other options if you simply type 'sealing rusty tank interior' into google. Sadly, it's a common problem when restoring motorcycles.
Fauna Tester- Seattle, Washington, USA
October 9, 2013
A. If you spend a lot of time and money, you have about a 1% chance of doing a good enough job electroplating the inside a gas tank.
There are several companies who will properly hot dip galvanize the inside of gas tank for a reasonable price, and it will then last longer than the rest of the bike.
Check on the internet.
Jeffrey Holmes, CEF
Spartanburg, South Carolina
October 10, 2013
Q. I restore antique and classic motorcycles and since spares are non-existent I was wondering if there is some way to coat the gas tank from the inside. There are no leaks and if you could do something like a zinc coat from.the inside to extend their lifespans?
Hugh DonnellyRestorer - Lonavla Maharashtra India
October 23, 2017
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