derusting

Ronnieroadster said:
I use powder citric acid and water. Easy to use and easy to get on Ebay. Mixing amounts are easy to find on line.
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This makes a solution that is essentially the same as "Evaporust" or "Rust-911". I have found the most efficient mixture is 1 lb to 5 gallons of water. It will work quicker mixed stronger, but then the cost goes up. If you use this, add a couple of caps of Dawn dishwasher liquid to act as a surfactant. The detergent will help break down any oil that may be present and will make the solution work better. This method, either commercial or home-made, is probably the best way to go about this. It will get rid of the rust and not damage anything else.
 
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ATF and Acetone is a superior penetrating oil (or so I have been told), but for removing rust, an "Evaporust" type solution can't be beat. Two different methods for two different purposes.
 
I have use molasses from feed store and water in a 4 to 1 mixture. Need to be careful as it can eat metal. Must watch progress. A friend used it on a Bristol block and ruined it as he left it in for months. Dave/Green Bay
 
Ronnie roadster: Thanks all. how long do I soak it? We are talking about the entire 39 Tyranny. Previously I soaked it for several days in white vinegar. All the rust was removed from the open surfaces. Looks great. It did not get the rust where the teeth were meshes, on the bearing surfaces and bearing-race contacts with the case. The gears do not turn as yet.
 
Remember any acid you use will also remove good metal as well. That is the advantage of a non-acid rust remover.
 
Evaporust and Rust-911 are not acids, they work using a chelation process.

"EVAPO-RUST works through selective chelation. This is a process in which a large synthetic molecule forms a bond with metals and holds them in solution. Most chelating agents bind many different metals. The active ingredient in EVAPO-RUST bonds to iron exclusively"

Citric acid does seem to have some good qualities:

"Another crystalline organic acid that actively dissolves rust without attacking the metal is citric acid. It occurs natural in many fruits and has the added benefit of not being appreciably toxic. In fact the supersoar candies sold in stores are lace with crystals of citric acid! None the less, eating citric acid is not recommended as it might damage your tooth enamel. Like oxalic acid a fairly dilute solution can be used. When rusty parts are left overnight, the rust will be gone."
 
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Citric acid is used as a chelating agent....but you have to adress the PH level to make it softmetal safe.
EDTA and Citric acid is among the more common base agents for the "safe" derusting products.
A simple way to adjust the PH is to add amonia...this will make it less agressive...but the ion exchange of the chelating process will still be there.
 
I have an interesting experiment going right now. My neighbor gave me a complete SouthWind gas heater he literally found in the woods. It had to have been there for years. I brushed most of the crap off and put it in some "Rust-911" I had going for something else and wasn't completely "used up". After two days, it looked a lot better than I thought it would, so I put it in it's own batch in a 5 gallon bucket. I'll post some pictures when I get done.

For my next trick, I have the world's rustiest '35 wire wheel, a brand new 5 pound bag of citric acid, and a big plastic tub. It'll be interesting to see how that turns out as well! Stay tuned, boys and girls!
 
I've used muriatic acid & water where I could put the part in & let it soak .
Don't use it with aluminum as it will dissolve it . Works great if you have aluminum piston scuffs in a steel cylinder --rather than honing it out , wipe the scuffs w/ a cloth w/ the acid & they will be gone . Then a cloth w/some water, dry , then oil . Just be careful as this acid is very caustic & not to be inhaled .Also have used this in a non aluminum radiator by filling w/ all in & out holes plugged .
 
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what would you use on a large item like a transmission case? Is there anything you can paint on or does it just dry up.
 
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