Rust Removal Tricks

[Peter]

OK guys. this is kind of funny, but honestly it isn't a joke.


The information that follows was compiled by me and is legit as far as I can tell.....
I'd love to hear your thoughts/experiences/feedback/chuckles or just plain reaction to it.

I've given the EvapoRust stuff a go and it works pretty well.
I am also a fan of "The Must For Rust" by Krud Kutter for taking out "ditch marks" and rust stains from fiberglass.
I actually have citric acid in my kitchen. I can tell you that stuff is super sour!


TRICKS FOR DEALING WITH RUST


EvapoRust

non-toxic and effective, but the parts should be immersed in it. Then scrubbed clean while still wet if a shiny surface is required. Or left to dry darkened to protect them from future rust.

After the process the EvapoRust can be strained and stored for re-use.

Disposal is to wash it down the drain. It is totally non-toxic.

Ingredients are proprietary and not listed as part of any safety regs because they are non-toxic. It most likely contains water, phosphoric acid; citric acid; and sugar. These are the basic ingredients of Coca Cola. EvapoRust looks suspiciously like flat Coca Cola.


HANDLING ACIDS:

*ALWAYS ADD ACID SLOWLY TO WATER NEVER ADD WATER TO ACID

ADDING WATER TO ACID CAN CAUSE IT TO SPLATTER.

“A” BEFORE “W” => => ACID to WATER

THINK OF ADDING ACID TO WATER BECAUSE THE FIRST FEW DROPS OF ACID IN A BIG BUCKET OF WATER MAKE A VERY, VERY DILUTE SOLUTION, THEN YOU GRADUALLY BRING UP THE ACID CONCENTRATION.

PH STANDS FOR “POTENTIAL HYDROGEN” IT IS THE H+ IONS THAT MAKE AN ACID, SO MORE H+ IONS, THE MORE ACIDIC THE SOLUTION….

BUT THE PH NUMBER IS TELLING YOU HOW MANY SPACES TO THE RIGHT OF THE DECIMAL POINT YOU ARE. SO PH OF 3 = 0.001 IS MORE ACIDIC THAN A PH OF 7 WHICH = 0.0000001 EVEN THOUGH “3” IS LESS THAN “7.”

THIS IS NOT INTUITIVE AT FIRST. THE CONVENTION LEAVES OUT A MINUS SIGN!

PH OF 7 IS NEUTRAL


Phosphoric Acid

Go-To rust remover for decades. Use in concentration of 20 to 30 %.

Phosphoric acid converts iron oxide to iron phosphate. Iron phosphate is water soluble. Technically this means that phosphoric acid is a “converter” not a “remover” but once converted the rust is now usually a dark film which can be washed away with a stream of water and a scrubber.

Phosphoric acid is also used as a rust converter where the rust is neutralized but left in place. Then it can be painted over, but because of the water solubility I doubt water based paints would be a good choice. Also the converted rust should not be left unprotected in the elements because normal rain would wash away the converted rust and you would only get right back to where you started.

Also used as a prep solution for painting metal parts.

Also used as a metal etch for cleaning gas tanks

Neutralize with soda ash from pool supply stores

Phosphoric acid is a big ingredient in colas and some other foods to make them sour. It has been said that Coke would be more sour than lemon juice if there wasn’t a ton of sugar in it.

Phosphoric acid is readily available and relatively cheap.

It can be obtained in high concentrations from sources such as Amazon for food use. Observe safety precautions when diluting to use as rust remover!

1 part 99% phosphoric acid added to 4 parts water is a 20% solution.

1 part 85% Phosphoric acid added slowly to 4 parts water is close enough to a 20% solution.

Phosphoric acid was and still may be sold in hardware stores as “OSPHO” by SkyBrite. I do not know the concentration.

It is the active ingredient in products like “The Must for Rust” by Krud Kutter.

Phosphoric acid can be strained and stored and re-used. A drum of it diluted to 20% would last most people a lifetime. A few gallons several years.

Naval Jelly

Is just phosphoric acid in a gel form to stick to vertical surfaces.

Muriatic Acid

AKA hydrochloric acid
Also used to remove rust but can etch metal if left in the solution too long.

I do not know what concentrations people use for this purpose.

Muriatic acid used to be sold as a mason’s supply for cleaning brick and concrete. I do not know if it is still available.

It is also used to lower the PH in swimming pools.



Citrtic Acid

Also suggested as rust remover. Common food additive available at places like Amazon. It is used to make things sour. Intensely sour.. a little goes a long way in cooking.

I have no idea what concentrations people would use this in for removing rust.



Feed Grade Molasses

also referred to as “BlackStrap” molasses.
“Molasses” are what is left after extracting the sugars from the cane or beet juice. There are differing grades of molasses. The lighter the molasses, the finer the grade. Blackstrap is the last version which has had nearly all of the sugar extracted and is very dark. It is mostly used for animal feed stock but also in some recipes for human consumption.

Low sulphur molasses is only available form sun ripened sugar cane. Green cane and other sources produce high sulphur grades of molasses. Repeated processing results in the blackstrap or feed grade molasses.

One person reports that diluting feed grade molasses 5:1 with water in a tub and immersing the rusted item will remove the rust in about 2 weeks. The liquid will ferment during this time so make allowances for that. The remainder liquid is a good fertilizer.

COKE:

Surprisingly this all adds up to support the urban legend that Coke is a pretty good rust remover. I can’t imagine why I would go looking for black strap molasses if I could just buy a Coke and use that.


Peter

[PeterPalmieri]

I only use

Rust-eze Medicated Bumper Ointment

[CamB25]

Coke is loaded with acids and makes a great cleaner. I use it to clean off the nasty dried on goo that forms on my saxophone moutpieces. Makes me wonder what it does to my stomach...

I just edited a rather lengthy and technical report on corrosion prevention/mitigation (don't ask, it's work). This stuff tested very well on carbon steel (rail steel) subjected to an extreme saltwater and humidity corrosion cycle.

http://www.eoncoat.com/" onclick="window.open(this.href);return false;

I haven't tried the bumper ointment yet...still too young for the proctologist!

[Bill Fuller]

Peter,

Very nice write-up. But you have one very important mistake. Muriatic acid is not sulfuric acid. Muriatic acid is hydrochloric acid. There a huge difference in what they each do. Hydrochloric acid is swimming pool acid and sulfuric acid is battery acid. You do not want to use sulfuric acid to clean anything, as it will vigorously attack anything organic.

Bill

[Rawleigh]

Also Evaporust works really well!! I use it on machine tools.

[Peter]

Good catch, Bill !

I edited the original to make the correction.

Thanks.


Muriatic acid IS still available at hardware stores.

I also found the following information (paraphrased by me):

Unlike phosphoric acid wash the hydrochloric acid wash does not leave behind any protective coating and instead may actually accelerate the formation of new rust. To prevent this one must neutralize the acid, which is very difficult to accomplish 100%. Neutralizing the acid on cast parts which tend to have surface pores is nearly impossible. Once parts are "contaminated" with hydrochloric acid it is said that they they will be nearly impossible to maintain rust free.

Also:

"Diluted muriatic acid rapidly dissolves iron at the same time that a large quantity of hydrogen is disengaged, and the mixture becomes hot."

"Phosphoric acid unites with iron, but very slowly."

So if you leave a part in the muriatic acid too long it gets eaten away. But if you leave it in phosphoric acid too long it gets a protective coating.

Ancillary to the discussion it turns out that muriatic acid is brutal on aluminum. It is sometimes used to etch/clean aluminum parts like wheel rims but it is pretty reactive with AL. If you Google "muriatic acid and aluminum" the first hits you get will be a video of a "muriatic/aluminum foil explosion." Still some car guys swear by it. You won't create an explosion spilling some on your aluminum rims or rub rail or whatever, but proceed with caution.

Peter