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Lotus Europa Forums => Garage => Topic started by: Grumblebuns on Friday,May 30, 2025, 08:14:11 AM

Title: Chemical Rust Removal
Post by: Grumblebuns on Friday,May 30, 2025, 08:14:11 AM
In the process of investigating rust removal for my Europas spare seat runners, I came across a YouTube video for a chemical method that looks promising. I was initially going to use the standard EvapoRust but at the current price of $28 per gallon at Harbor Freight I started looking for alternatives when this video showed up on my YouTube feed.

https://www.youtube.com/watch?v=fVYZmeReKKY

Reading the first 30-35 comments, the consensus is extremely positive from the people who had tried it. So, I’ve ordered a 2 lb bag of citric acid powder and a digital grams scale from Amazon and will try the process myself. The attractiveness of this process is the minimal effect on the base metal, the low cost of the materials and the effective longevity of the solution compared to EvapoRust . I’ll report back on its effectiveness on my seat runners in a couple of weeks, If anyone wants to try the solution here are the ingredients:

The recipe:
 Per 1L of H2O
1: 100 Grams Citric Acid.
2: 40 Grams - Sodium Carbonate /OR/ 63 Grams - Sodium Bicarbonate /OR/ 30 - Grams Sodium Hydroxide.
3: Add ingredients from 1 & 2 to the water.
4: Wait for reaction between Acid and Base to complete.
5: Add final ingredient: Arbitrary amount of liquid dish soap (or other wetting agent / surface tension reducer).


Title: Re: Chemical Rust Removal
Post by: gideon on Friday,May 30, 2025, 10:22:40 AM
Interesting video.  What do you plan to do after soaking parts in this liquid to prepare for paint?
Title: Re: Chemical Rust Removal
Post by: TurboFource on Friday,May 30, 2025, 01:21:17 PM
Cleaning vinegar and salt solution works well ….
Title: Re: Chemical Rust Removal
Post by: dakazman on Friday,May 30, 2025, 03:01:22 PM
  I like white vinegar. 2x on vinagar :I-agree:
Dakazman
Title: Re: Chemical Rust Removal
Post by: gideon on Friday,May 30, 2025, 06:13:16 PM
Vinegar will dissolve rust and also a very small amount of good metal.  Products like Evaporust work by chelation which is a different process that doesn't dissolve the non-rusty metal.  If you should ever be unfortunate enough to suffer from heavy metal poisoning, and get treatment for it, then they will treat you with chelation rather than pickling you in acid.  It's more gentle.  You can drop a piece of rusty steel into Evaporust, check on it a week later and there will be barely any loss of non-rusty steel.

The author of the video claims to have found a simple formula using household chemicals that is as effective as Evaporust, but is much cheaper and also the solution remains effective much longer.  That's a pretty bold claim, and if he's right then it's worth knowing about.

Vinegar works, and if that's what you have and you can leave the parts in vinegar for the right amount of time then that's often good enough.  But if there were a better method available that doesn't cost any more, wouldn't you want to know?

By the way, for rust removal by acid I recommend citric acid instead of vinegar.  They both work, but citric acid smells nicer :)   Alternatively, you can remove rust by chelation in a molasses and water solution.  It's cheap, but very slow.


Title: Re: Chemical Rust Removal
Post by: 4129R on Saturday,May 31, 2025, 06:58:26 AM
Has anyone tried using Coca-Cola ?
Title: Re: Chemical Rust Removal
Post by: Bryan Boyle on Saturday,May 31, 2025, 07:47:51 AM
Has anyone tried using Coca-Cola ?
Phosphoric acid, I believe.

I'm a believer, for large items, especially things like gas tanks, etc. of electrolytic derusting using sodium carbonate (washing soda), an iron rod, and a 12v/5A power supply.  Doesn't remove base metal, and leaves the surface ready for refinishing.  YMMV, but I've had good luck with it.
Title: Re: Chemical Rust Removal
Post by: berni29 on Sunday,June 01, 2025, 12:05:45 PM
Hi

Great video, gonna try this out. Starting with a couple of Europa petrol tanks that I had powder coated. Chemicals arrived today.

What do people suggest to coat the insides of the petrol tanks with afterwards?

Many thanks

Berni
Title: Re: Chemical Rust Removal
Post by: kram350kram on Monday,June 02, 2025, 05:32:20 AM
Electroless nickel if your tank is solid, if you have pin holes you’re stuck with a liquid liner.
Title: Re: Chemical Rust Removal
Post by: Grumblebuns on Monday,June 02, 2025, 08:59:18 AM
I'm a day and a half into the citric acid and sodium process and the rust removal is visible but is relatively slow. I figure at this rate it will take another day, perhaps two before the process is good enough to remove the runners. I had to use two gallons of water to completely cover the parts. The issue was finding a container that the parts would fit in and still be fully covered.

All of the processes that people have mentioned will work. It's a matter of cost, time and damage to the base steel. I will use EvapoRust or other the commercially already mixed available products only for small items due to cost. All other tasks, either the acids (Coke/Pepsi, vinegar, molasses) or electrolysis. I found another video by Project Farms on the comparison of EvapoRust vs electrolysis. I'm impressed with how well electrolysis works.

https://www.youtube.com/watch?v=8dtDLQHjHBc&list=PLVI6drejxJEDFDJIzwMOTBdRd408aJqgF&index=64
Title: Re: Chemical Rust Removal
Post by: dakazman on Monday,June 02, 2025, 01:19:59 PM
If you really want to eat rust off immediately brush on or soak in muriatic acid available at Lowes or Home Depot or swimming pool supply.
 Use outside only and you can dilute it more than 50 percent . Always pour acid into water.
Spray off with water afterwards then sandblast for bare metal look.
Dakazman