The joy Of Citric Acid

[scockram]

Just what I've been thinking.

 

[Vulcan]

^^^^^^^^^^^^^^^^^^^^^^
I have used both methods.
Never have I had the acid etching the metal.

Really, you couldn’t see the difference between the two? Using acid will etch the surface resulting in a matt grey finish. Using washing soda and a battery charger simply removes the rust, any shiny non rusty areas remain untouched.
I’ve seen many measuring tools and calipers etc ruined by attempts to remove the rust with acid.

 

[Jake]

The idea is that it makes sodium citrate, which is a chelating agent. Rather than just attacking with acid, that reduces the rust by pulling the iron out of the rust and into the solution. I think, being way over the ends of my crappy chemistry skis.

 

[diytoolbox]

I have a question based loosely on the chemistry classes I took in high school, early 70's. That being an acid when mixed with a base neutralizes the solution to water and a salt. So how does mixing citric acid with the soda not reduce the effectiveness as it is neutralized?

Pete

Good question. Answer? I don't know.

 

[diytoolbox]

I have now used the citric acid, baking soda and squirt of handwash soap mixed in tape water solution for removing rust from my vintage wood carving gouges.

It seemed working very fast. Within 1 - 2 hours, the gouges rust were disappearing. After 3 hours, they were taken out from the solution, and rinsed in tap water, and dried with clean dry towel.

The rust seemed to have gone, but the metal of the gouges have dark grey surface now. They used to be shiny silvery surface before (with rust spots of course). But after de-rusting, the metals look dark grey on the surface? Why is that?

 

[Cozzer]

I have now used the citric acid, baking soda and squirt of handwash soap mixed in tape water solution for removing rust from my vintage wood carving gouges.

It seemed working very fast. Within 1 - 2 hours, the gouges rust were disappearing. After 3 hours, they were taken out from the solution, and rinsed in tap water, and dried with clean dry towel.

The rust seemed to have gone, but the metal of the gouges have dark grey surface now. They used to be shiny silvery surface before (with rust spots of course). But after de-rusting, the metals look dark grey on the surface? Why is that?

Pass.
Never had that myself, but in fairness most things I've done have been "dull" to start with...although the seized secateurs were shiny and still are.
From your previous posts I'd guess you were fairly accurate with your measurements (although I suspect they're not crucial to a few grams).
If so - and you can rule out the container? - there's only one element left.
The tap water.
Hard? Soft?
Could it really make a difference?
Find it hard to believe, but.....?

Edit : Forgot the plane chip breaker...was, and still is, shiny....

 

[Chris152]

I went to buy the stuff on amazon, had the washing soda in the basket, then saw the price of citric acid and realised it's not much more for the (very cheap) car battery we need. So that went in the basket instead and we ended up trying electrolysis. It's very exciting to watch all the bubbles fizzing away from the tool, I've yet to try citric acid but can't imagine it's as much fun!

 

[Vulcan]

The rust seemed to have gone, but the metal of the gouges have dark grey surface now. They used to be shiny silvery surface before (with rust spots of course). But after de-rusting, the metals look dark grey on the surface? Why is that?

This is what I have been saying. The acid has, however slightly, *etched the surface. Washing Soda and an old cheap battery charger Does Not do this.

I’ve used both methods a couple of times before giving up on Citric Acid.

* Others can be pedantic and use another term but it still amounts to surface damage, however slight.

 

[diytoolbox]

I went to buy the stuff on amazon, had the washing soda in the basket, then saw the price of citric acid and realised it's not much more for the (very cheap) car battery we need. So that went in the basket instead and we ended up trying electrolysis. It's very exciting to watch all the bubbles fizzing away from the tool, I've yet to try citric acid but can't imagine it's as much fun!

This is what I have been saying. The acid has, however slightly, *etched the surface. Washing Soda and an old cheap battery charger Does Not do this.

I’ve used both methods a couple of times before giving up on Citric Acid.

* Others can be pedantic and use another term but it still amounts to surface damage, however slight.

Problem with electrolysis is that it takes too long time for de-rusting because you can only do 1 tool at a time. If you had 3 dozen of carving gouges to derust using electrolysis would take days and weeks or even months.

Citric acid solution can take 10 gouges in a bottle at one go, and just leave them for an hour two, and rinse wash and dry, and you are done.

I am not sure the acid etching is happening with the citric acid solution derusting, and if it were, it still looks rust free with dark grey coating on the metal surface which might prevent rusting. It is better than the tools with loads of rust.

 

[diytoolbox]

Pass.
Never had that myself, but in fairness most things I've done have been "dull" to start with...although the seized secateurs were shiny and still are.
From your previous posts I'd guess you were fairly accurate with your measurements (although I suspect they're not crucial to a few grams).
If so - and you can rule out the container? - there's only one element left.
The tap water.
Hard? Soft?
Could it really make a difference?
Find it hard to believe, but.....?

Edit : Forgot the plane chip breaker...was, and still is, shiny....

I am not sure what type of tap water we have here. It is just cold tap water in the bathroom used mixing with citric acid, baking soda and hand soap. The tap water was used to rinse and wash the tools after the soak.

I was wondering if I am doing something wrong, which could be adjusted or changed. Will keep experimenting. My old tools being derusted with the acid solutions are almost for scraps anyways, and they have been used for practicing sharpening practices.
Nothing valuable or expensive in the rusty tool pile in the garden shed.

 

[Chris152]

Problem with electrolysis is that it takes too long time for de-rusting because you can only do 1 tool at a time. If you had 3 dozen of carving gouges to derust using electrolysis would take days and weeks or even months.

Citric acid solution can take 10 gouges in a bottle at one go, and just leave them for an hour two, and rinse wash and dry, and you are done.

I am not sure the acid etching is happening with the citric acid solution derusting, and if it were, it still looks rust free with dark grey coating on the metal surface which might prevent rusting. It is better than the tools with loads of rust.

I've not really tried, but my understanding is, as long as components are connected to the negative, the process will work. So you can bundle several things together, or connect them all individually to the negative cable, and it'll work for all. I tried dropping an old spanner on top of a file we were de-rusting, and it too started fizzing away.

 

[kinverkid]

Problem with electrolysis is that it takes too long time for de-rusting because you can only do 1 tool at a time. If you had 3 dozen of carving gouges to derust using electrolysis would take days and weeks or even months.

Citric acid solution can take 10 gouges in a bottle at one go, and just leave them for an hour two, and rinse wash and dry, and you are done.

I am not sure the acid etching is happening with the citric acid solution derusting, and if it were, it still looks rust free with dark grey coating on the metal surface which might prevent rusting. It is better than the tools with loads of rust.

There's no reason you can't do more than one tool at a time using electrolysis. I often use it to de-rust multiple items. I might strip down a hand plane and put the body, frog, iron and screws separated in the same bath attached to a low powered car-battery charger. Chrome items are done outside if not using the vinegar or citric method. The best scenario would be to have all the above methods (they all work) available, look at the item to de-rust, and then decide which method to use. e.g. plane body and frog - electrolysis especially if you want to preserve the paintwork. The iron and screws, any of the previously mentioned methods. Brass items, metal cleaners like Brasso or use a buffing wheel. Un-handled or plastic-handled items any method above. Wooden handled items, to avoid staining, either remove the handle, try and soak in citric or vinegar mix with the handles hanging out of the solution or electrolysis making sure the buoyancy of the wooden part does not allow the tool to freely float around.

 

[Fergie 307]

I have now used the citric acid, baking soda and squirt of handwash soap mixed in tape water solution for removing rust from my vintage wood carving gouges.

It seemed working very fast. Within 1 - 2 hours, the gouges rust were disappearing. After 3 hours, they were taken out from the solution, and rinsed in tap water, and dried with clean dry towel.

The rust seemed to have gone, but the metal of the gouges have dark grey surface now. They used to be shiny silvery surface before (with rust spots of course). But after de-rusting, the metals look dark grey on the surface? Why is that?

You get the same effect using phosphoric acid. Don't know what it is, not a chemist!
But give them a rub with wire wool and it will come off and get you back to a nice shiny steel.

 

[Fergie 307]

There's no reason you can't do more than one tool at a time using electrolysis. I often use it to de-rust multiple items. I might strip down a hand plane and put the body, frog, iron and screws separated in the same bath attached to a low powered car-battery charger. Chrome items are done outside if not using the vinegar or citric method. The best scenario would be to have all the above methods (they all work) available, look at the item to de-rust, and then decide which method to use. e.g. plane body and frog - electrolysis especially if you want to preserve the paintwork. The iron and screws, any of the previously mentioned methods. Brass items, metal cleaners like Brasso or use a buffing wheel. Un-handled or plastic-handled items any method above. Wooden handled items, to avoid staining, either remove the handle, try and soak in citric or vinegar mix with the handles hanging out of the solution or electrolysis making sure the buoyancy of the wooden part does not allow the tool to freely float around.

Brass can be cleaned really well using white vinegar with a dessert spoon of salt per litre. Heat it up until the salt is fully dissolved. Keeps for quite a while in a jar. Will quickly remove verdigris and tarnishing.

 

[Fergie 307]

This is what I have been saying. The acid has, however slightly, *etched the surface. Washing Soda and an old cheap battery charger Does Not do this.

I’ve used both methods a couple of times before giving up on Citric Acid.

* Others can be pedantic and use another term but it still amounts to surface damage, however slight.

The grey does seem to be a surface deposit, rather than etching. If you rub the part with a scotchbrite pad it comes off, leaving a black deposit on the pad.
You are right of course that etching will take place, it is acid afterall.
You can show this by simply putting a highly polished piece in the solution. It will dull. However, with citric at these concentrations it is so slight that even a quick rub over with wire wool or a polish will restore the finish.
As you say, horses for courses.

 

[diytoolbox]

Yes, the dark grey stuff on the surface seems easily come off with soft wire wool or sand paper rub, if you want the shiny metal surface. It doesn't seem to be damage or hard etching into the metal.

I did another de-rusting session on the old rusty carving gouges with the citric acid and soda. This time the soaking was only for 45 minutes, a lot shorter time than before, and voila there was no dark grey surface. The old tools came out with shiny metal surface with the rust cleaned off. Great.

 

[Vulcan]

Problem with electrolysis is that it takes too long time for de-rusting because you can only do 1 tool at a time. If you had 3 dozen of carving gouges to derust using electrolysis would take days and weeks or even months.

Citric acid solution can take 10 gouges in a bottle at one go, and just leave them for an hour two, and rinse wash and dry, and you are done.

I am not sure the acid etching is happening with the citric acid solution derusting, and if it were, it still looks rust free with dark grey coating on the metal surface which might prevent rusting. It is better than the tools with loads of rust.

Untrue. I’ve done several small pieces at a time. It’s not difficult to put more than one lead on the negative side of the charger.
As for time, do you stand and watch your kettle boil or do you carry on with something else. Same with the washing machine or the oven …

If you’re removing the surface deposit with sand paper or scotchbrite you’re abrading it again.
If you want to derust anything that has a bright surface in some places or has markings etc then Electrolysis is still the way to go.
I’ve seen some lovely old tools destroyed with Acid de-rusting.