Vinegar leaves a black substance on the item that needs to be cleaned off. And don’t leave it too long. Ask me how I know.
Evaporust
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Combat Doc
ArboristSite Lurker
I've used lots of Evaporust as well as Rust 911. Initially I found that the Evaporust worked a little better that the Rust 911 but I began adding a tablespoon of Dawn dishwashing detergent to the gallon of diluted Rust 911. With that they are so close that I can't tell the difference. The Evaporust contains a surfactant that gives it a slippery feeling and a slight foam when you poor it. The surfactant (and Dawn) helps dissolve any oils or dirt that may still be on the metal so that the chemicals can contact the rust more effectively. I also use a bucket heater to make them work faster. It heats the water up to 185F. Can pretty much derust anything in 8 hours with a fresh batch. The bucket heater also melts any oil or grease that I may have missed so I don't spent so much time cleaning. I still wash it as best as I can but don't fret that it's spotless. It slows down(regardless of temperature) as you use up the active chemicals until it will eventually stop working altogether.
if you clean the heavy rust off first it works much better and doesn't contaminate the evaporust as much and you can use it more times.
SS, this is my preferred method. 1 TBLSP. Arm & Hammer washing soda per gallon of water, enough to cover the part. Use a sacrificial anode, a 12V battery charger (old style), connected + to anode, - to the part you want to clean, leave in 4-8 hrs., depending on severity of rust. Remove, rinse, and dry. Either oil lightly, or prime for painting. Waste liquid is non-toxic.
It’s been about 18 hours 
Definite progress
Definite progress
I like evaporust for small stuff. Larger things get wire wheeled/de scaled or blasted then coralseal or por-15 mopped on. Getting rid of the rust is only part of the issue, keeping it gone is another issue, especially on things that live outdoors or drive on our heavily salted winter roads. The coralseal has been a trial for me. Por-15 is just too expensive and still needs a topcoat, but works amazingly well. Never tried rust 911. May have to grab some and try it. Good topic!
That’s the method I used on several vintage motorcycle tanks. It works great.
3 1/2 days looks pretty good to me
Before
After
So at 1/4 the price of Evaporust I think it’s a good deal
Before
After
So at 1/4 the price of Evaporust I think it’s a good deal
KostasVolos
ArboristSite Operative
Oxalic acid .
It's sold in the form of crystal powder.Used by honey producers to treat an illness of bees.
Dilute it inside water and apply to rust with a brush.
Let it act for 30 minutes.
Rinse with clean water.
Rust is gone .
"Applications
Oxalic acid's main applications include cleaning or bleaching, especially for the removal of rust (iron complexing agent). Its utility in rust removal agents is due to its forming a stable, water-soluble salt with ferric iron, ferrioxalateion. "
https://en.m.wikipedia.org/wiki/Oxalic_acid
https://beekeepers.com/products/wood-bleach-1-lb
https://www.loudwolf.com/storefront/index.php?route=product/product&product_id=2190
It's sold in the form of crystal powder.Used by honey producers to treat an illness of bees.
Dilute it inside water and apply to rust with a brush.
Let it act for 30 minutes.
Rinse with clean water.
Rust is gone .
"Applications
Oxalic acid's main applications include cleaning or bleaching, especially for the removal of rust (iron complexing agent). Its utility in rust removal agents is due to its forming a stable, water-soluble salt with ferric iron, ferrioxalateion. "
https://en.m.wikipedia.org/wiki/Oxalic_acid
https://beekeepers.com/products/wood-bleach-1-lb
https://www.loudwolf.com/storefront/index.php?route=product/product&product_id=2190
KostasVolos
ArboristSite Operative
Or you can make plenty of Evaporust with just mixing 90% w/w of distilled water with 10% w/w of EDTA .
https://www.loudwolf.com/storefront/index.php?route=product/product&product_id=1744
https://www.loudwolf.com/storefront/index.php?route=product/product&product_id=1744
Combat Doc
ArboristSite Lurker
Evaporust and Rust911 have a reducing agent and a chelating agent. EDTA is a chelating agent. Acids are reducing agents. The reducing agents in evaporust and rust911 are non acidic, if your'e not careful acids will eat into the iron/steel. The reducing agents in evaporust and rust911 only remove one of the oxygen atoms from the ferric oxide molecule(rust) The chelating agent then binds with the new molecule(ferrous oxide) and suspends it in solution. Neither the reducing agent nor the chelating agent in evaporust and rust 911 will react with elemental iron or steel. I don't work for either company. I've tried to discover which agents they use so that I can save some money but their formulas are proprietary. maybe a real chemist can help.
I tried EvapoRust (several brands, now that patents have expired (?), such as WD-40 rust soak, etc.), along either several types of acids, and electrolysis in my ‘Challenge Chain’ thread.
‘Inorganic acids’ (hydrochloric, sulfuric, nitric, etc.) are harder on metal. Some will damage adjacent chrome or aluminum. They can also case brittleness. ‘Naval Jelly’ is phosphoric acid.
‘Organic acids’ (citric, acetic, oxalic, etc.) remove rust and are more gentle on the underlying metal. Vinegar (acetic acid) can turn the metal black. Oxalic can turn the metal green. Citric acid was very cheap (powder bought on Amazon) and worked well without color changes.
The EvapoRust seemed to work best on surface rust.
As noted, clean and degrease the item first, so that the chemical can reach the rust. Knock off heavy or loose rust with a brush, ScotchBrite pad, etc., under water.
****Keep the soaking pan covered**** A chemist at EvapoRust told me that the product loses effectiveness as water evaporates from the solution. He said to reuse the solution until it no longer works.
Philbert
‘Inorganic acids’ (hydrochloric, sulfuric, nitric, etc.) are harder on metal. Some will damage adjacent chrome or aluminum. They can also case brittleness. ‘Naval Jelly’ is phosphoric acid.
‘Organic acids’ (citric, acetic, oxalic, etc.) remove rust and are more gentle on the underlying metal. Vinegar (acetic acid) can turn the metal black. Oxalic can turn the metal green. Citric acid was very cheap (powder bought on Amazon) and worked well without color changes.
The EvapoRust seemed to work best on surface rust.
As noted, clean and degrease the item first, so that the chemical can reach the rust. Knock off heavy or loose rust with a brush, ScotchBrite pad, etc., under water.
****Keep the soaking pan covered**** A chemist at EvapoRust told me that the product loses effectiveness as water evaporates from the solution. He said to reuse the solution until it no longer works.
Philbert
I am just wondering about vinegar and salt. Yes it will turn black so it must be treated but so do things when you use other agents.
