Home Chelation? Anyone tried?

So I know rust is an issue for everyone here, and removal is a real desire.  The current market leader for rust removal is Evaporust, and it's been around for a while.  But it's expensive, right?  Remember not long ago, someone posted an alternate maker that they bought at one of the discount stores.  Almost drove over to one to get some, but lazy and travel made it never happen.

Then the other day, I this video popped up in my feed- https://www.youtube.com/watch?v=fVYZmeReKKY&t=285s&ab_channel=BeyondBallistics

He did some research, and made his own chelation rust remover from water, citric acid, and sodium carbonate.  He also put up the recipe for sodium bicarbonate.  Since I was doing wine making a long time ago, I happened to have some powder citiric acid, and sodium bicarbonate is just baking soda.  Why not experiment?

Before

After

Not enough of a chemist to say anything intelligent on the matter, but I know one of the reasons EvapoRust is liked is how gentle it is to the material.  I also know that you start throwing acids and salts at metals and you often can get weird reactions that are not good for strength.

I'd want more info on the reactions before I tried it on structural members, myself.

So maybe hard to see, but the important part is that the threads are really clean and smooth now.  So it works.

Citric acid is cheap to get in volume on the big river outlet, and sodium carbonate and sodium bicarbonate is pretty easy to get locally (one on the laundry area the other in baking).  

The one thing I would change is a more neutral soap- I used some antibiotic hand soap, as it was handy vs. a spray dish soap I had.  But something really basic without any additives that will act as a surfactant- as I think some of the residue is from the soap additives.  Or even a better surfactant only- but I've not researched a neutral surfactant.  

Something to consider if you have rust to remove.

Mr_Asa said:

Not enough of a chemist to say anything intelligent on the matter, but I know one of the reasons EvapoRust is liked is how gentle it is to the material.  I also know that you start throwing acids and salts at metals and you often can get weird reactions that are not good for strength.

So the guy doing it is a gun restorer (I assume) so not attacking the base metal is pretty important.  That's why he added sodium carbonate to the citric acid- to raise the PH and change the chemistry.  

Given people have used straight vinegar, which is just acid, I'm less worried about the problems for what I'm doing.

So a little looking up what is happening. 
 

citric acid plus sodium bicarbonate results in sodium citrate and co2. 
 

sodium citrate is a rust inhibitor for steel. 
 

this is an edit. The citric acid is completely changed. And the left over sodium citrate does chelate with the ions in rust- making it soluble in water. Thus dissolving the rust and not reacting with the base steel. Which is how Evaporust works. 

How long did you soak the bolts in your solution concoction?

I've been letting them sit for 24 hours. 

That's pretty cool. Thanks for sharing!

alfadriver said:

Mr_Asa said:

Not enough of a chemist to say anything intelligent on the matter, but I know one of the reasons EvapoRust is liked is how gentle it is to the material.  I also know that you start throwing acids and salts at metals and you often can get weird reactions that are not good for strength.

So the guy doing it is a gun restorer (I assume) so not attacking the base metal is pretty important.  That's why he added sodium carbonate to the citric acid- to raise the PH and change the chemistry.  

Given people have used straight vinegar, which is just acid, I'm less worried about the problems for what I'm doing.

I used salted vinegar and it derusted the parts I was interested in cleaning very well.  (351 Cleveland head and exhaust manifold bolts) They also rusted again extremely fast.

This looks a lot more interesting.

In reply to Pete. (l33t FS) :

Reading up on it, the sodium citrate does leave a protective surface. Supposedly. 
 

I've washed everything with water and then "fogged" them with wd40.  

Bring this back from the past (a little)- just saw a video where someone thickened the above solution with corn starch- and works really well as a gel.  The gel part is at the end of the video- https://www.youtube.com/watch?v=Gi4DqtpYAOI

Awesome. I have some brackets I need to de-rust before painting and I might give this a shot. 

Huh, I always thought "home chelation" was what my wife's former brother-in-law went to prison for. 

Edit: Now that I have a big boy battery charger, I'm intending to make large electrolysis tank with my old one. Hopefully big enough for a pickup fender or a door skin.

In reply to Crackers (Forum Supporter) :

I did the electrolysis thing when i was refurbishing the suspension on a Miata several years ago. I used a 30 gallon plastic garbage can then. I also have an extra 60 gallon garbage cart if I were to need it for something larger. I used chelation for the bolts and stuff though.

Wow, good to know. Thanks!

Use phosphoric acid, that is what most rust remover/converter is.

Guy here mentioned metal prep from home depot, it works.  

For sensitive stuff use electrolysis.  

benzbaronDaryn said:

Use phosphoric acid, that is what most rust remover/converter is.

 

Guy here mentioned metal prep from home depot, it works.  

For sensitive stuff use electrolysis.  

The point of chelation is to remove the rust without damaging the metal.  Acid damages the base metal.

Chelation is how EvapoRust works, and this is a considerably cheaper (and more effective) home method to do the same thing.  It's gentle, and does not require electrolysis. 

I'll toss in a comment regarding base metal attack and strength. Most steel alloys used for structural bolts aren't sensitive to forms of chemical attack we amateurs are prepared to throw at them. Short of full immersion in a hot, agitated vat of hydrofluoric acid in the backyard, there's not much chance of incurring a chemical-induced stress concentration or reduction in strength--especially no worse than what the rust that's being removed has already done and/or would continue to do left untreated. Biggest risk area on a bolt & nut combo will be right under the bolt head. Rust can be a pretty potent hazard to the microstructure and crack risk. I once had a common GR5 3/8 UNC hex bolt head split in half transverse to the bolt axis, effectively making me a pair of hexagonal 9/16" steel pancakes. Split started at a microscopic rust inclusion. Kept that one for the wall of shame.

Now, for high-strength ferrous fastener alloys (steels over ~180 ksi yield), hydrogen embrittlement, stress corrosion cracking (SCC), and a few other less common sensitivities can be a concern. The more exotic the material, the more exotic its warnings. Components found in the average project car which would warrant caution include things like rod bolts, valvesprings, main & head studs/bolts, and potentially highly-loaded suspension fasteners. If those sorts of parts are compromised, just buy new. (Corollary: never let these steels dry out. Always keep them oiled.) Non-ferrous materials also have some environmental factors to beware of, but none of them rust...

So one thing that chelation also does is put a surface on the metal to protect it from rust.  Which is nice when you clean them and then have to wait to put it all back together.

Once the acid is cleaned off, rust will start back up pretty quickly unless it's oiled.  

This isn't limited to just nuts and bolts, if people are thinking of chemically removing the rust from suspension pieces, may want to compare a gallon of store acid with making a gallon of this citric acid solution.  

A gallon of phosphoric acid from Lowes is about $10.

To make 4 L of the rust remover it's 

400g of citric acid powder which is about $4.50 (a 900g bag is $10)

240g of baking soda (about $0.50 and you probably have some in the kitchen already)

some drops of dish soap.

4l of water.  

So for half the price of a gallon of acid, you end up with a better way to remove rust.

Are you trying to remove the rust or not?  I like to use stuff that works in my lifetime.  Phosphoric acid converts iron oxide into iron phosphate, the black stuff.  You might have to surface treat it for flash rust.  

I don't want to argue the point if it isn't being received.  

I always thought people used molasses for chelation but I would just hit it with acid and be done with it.  

In reply to benzbaronDaryn :

Yea, I do.  It took a couple of hours and it was done.  I posted my results as did the authors of the videos I posted. 

Not sure what point isn't being received.  The whole point is to remove rust, right?  You want to use expensive acid, I'd rather use cheaper chelation that is also safer for the metal, me, and disposing of what's left over.  And I do NOT have to deal with any flash rust, as the metal surface gets protected in the process.

Evaporust has been doing this for years with very popular results, and this is just a different, homemade, version of that.  There's more out there than molasses to do this.  

I get that you love using P acid, but you might want to learn about these other alternatives.