Citric acid as rust remover

[Stein.S]

Hi.
I usually use citric acid when removing rust from gas tanks. Normally I use a mild solution and let the tank stand filled for a few days. Will this be a problem when the tanks are soldered together with tin?

[T. Cotten]

Citric acid flushes with water easily, Stein,..

And is perhaps the best agent, although I cannot find it locally any more (except Kosher at the grocery,...)

Since vinegar, muriatic, and other acids do not flush as clean, leaving distinct coatings, I suspect citric is more friendly to soldering.

My experience with it was Federal R&D, so we filled baths with reagent grade! ("Budget" meant: Use it all or you won't get as much next year.)

....Cotten

[Stein.S]

Thank you for answering my question.

[T. Cotten]

Thank you for answering my question.

The important thing, Stein,...

Is to let us know how it goes!

....Cotten

[aumick10]

Is there a concentration of citric acid that works best? Cheers

[T. Cotten]

Is there a concentration of citric acid that works best? Cheers

Its been too many decades to remember the Fed lab recipe, Mick!

(I could make up a number if I had to, and even convert it to a molarity.)

But since the heated tanks had crusts on the sides, I'd say it was 'supersaturated' in practice, although that's probably not the optimum, especially considering the expense.

...Cotten

[aumick10]

Thanks Tom, that helps.

[T. Cotten]

Thanks Tom, that helps.

Not really, Mick,

The heated tanks were used mostly for lab glassware, not fuel tanks, so a quick websearch seemed prudent, until none of the sources agreed.

One source cited a pound per pint, which sounds pretty saturated to me! Another prescribed a tablespoon per cup, so I guess its back to trial and error.

Let us know how it goes,

....Cotten

[aumick10]

I am still undecided whether to use electrolysis or citric acid. I have some cylinders that need cleaning, so i will have to check out the action of citric acid on cast iron.

[Stein.S]

I once used citric acid for cleaning rust from a cast iron 2-stroke cylinder. Had no problems. When drying the cylinder after it very quickly came a thin layer of new rust. So think good idea would be to dry it with air from compressor at once after picking up from acid solution.

Think solution I have been using is about 30 gram citric acid mixed with 5 liters of water. If possible the temperature should be high( max 60 degrees Celsius) Process works faster if temperature is high. Las time I cleaned tanks I just filled the tanks and let them stand outside for maybe 3 days. Sun heated the tanks daytime.

I know the mix acid/water I have been using is mild compared to the mix other people use. I dont know what is the right mix , but it worked for me.

[T. Cotten]

The flash of fresh rust, Stein,

Can be avoided by quickly using WD-40 after the last hot water wash; The WD stands for 'water dispersant', and should be used to scrub the bore cross-hatch clean before oiling.

...Cotten

[Stein.S]

Wd-40 will work. I am sute. The cylinder I cleaned was supposed to be spray painted with black heat restant paint, so had to keep it clean and dry. And that instant rust does not matter much. All in all I think citric acid works fine. When doing carburators made by aluminium it will be a white/grey coloured surface after. Not sure, but suspect it will eat the aluminium if treted in the acid bath for a long periode of time. So Maybe not a good idea….

[T. Cotten]

I have no experience with citric acid on carbs, Stein,

The only carbs that crossed my benches that seemed like an aluminum alloy were GX Scheblers. and those required a LOT more than a soak!

Even white vinegar can get you in trouble if too hot or soaked too long, and invariably needed mechanical cleaning anyway.

My ultrasonic never took anything all the way either, but citric acid would be a worth a try.

....Cotten

[aumick10]

I find vapor blasting is the best process for cleaning carbies. Wash with hot water and air. The glass is too small to block most ports. I think from memory citric acid will eat aluminum over time.

[T. Cotten]

The biggest problem I have with citric acid, Folks,..

Is that I can only purchase it on the interwebs.

Even the dear Kosher went missing at the "grocery".

....Cotten