Citric acid..

Chris C

Chris
Senior User
Has anybody used citric acid for rust removal? I've seen it discussed so I though I'd give it a try. If so... What was your mix ratio and was it effective?

20200708_122131.jpg
 

MarkE

Mark
Corporate Member
I used it quite a bit. It works pretty well.

A weaker solution takes a bit more time, but seems safer. I never really measured, just dumped a small amount in a container and added water. Once the rusty item was placed in the solution I checked it after 10-20 minutes or so and looked for bubbling/fizz on the metal surface and added more acid or more water depending on how active the bubbling looked. Not really very exact, but it worked fine.

If you use a strong solution, leave your items in for a shorter period of time. Weaker solution, more time. Steel parts, screws and such could stand more time. Cast iron can get pitted if left in too long.

Just keep checking your parts every few minutes to see how they look. After a while you will get a feel for how long things take. I used a stiff nylon brush on flat surfaces to see how the solution was working.

Don't forget to rinse with clean water when you are done and dry as thoroughly as you can. You will get flash rust pretty quickly after, but it removes easily with a non-woven pad (Scotch Brite)
 

nn4jw

Jim
Senior User
I've used it when restoring bits and planes. I really didn't do anything different than Mark described once the ratio of water to powder (from internet searches) just didn't seem strong enough. I adjusted the same way.
 

Oka

Oka
Corporate Member
Yup, it works well, it can also be used to discolor wood if you want to, so can Baking soda, depends on the wood.
 

Chris C

Chris
Senior User
Agreed that Evaporust is an awesome product...I use it all the time.

It's also expensive and I've found it's re-use efficiency falls quickly. I was looking for an alternative that's more friendly to the wallet.
 

KenOfCary

Board of Directors, Secretary
Ken
Staff member
Corporate Member
Does the citric acid leave the same dull look that Evaporust does? Never liked that about Evaporust, but for an old metal hammer or such, it didn't really matter much.
 

Jeff

Jeff
Corporate Member
Agreed that Evaporust is an awesome product...I use it all the time.

It's also expensive and I've found it's re-use efficiency falls quickly. I was looking for an alternative that's more friendly to the wallet.
I see Evapo-rust online for $17-24/gallon. I don't know how much of your 5 lb bag would be used in a typical rust remover solution or how fast it will lose it's efficiency (3-4 times?).

Your Spicy World citric acid is about $17
 

bbrown

Bill
User
I pour water in the half gallon milk jugs, stir in a 1/4 cup of citric acid, and put plane parts in it. If no bubbles come, then just add more citric acid. 1/2 cup citrate to a gallon water - can use large HD or Lowes buckets for plane bodies. This works well for me. Rust scrubs off easily
 

Jeff

Jeff
Corporate Member
I pour water in the half gallon milk jugs, stir in a 1/4 cup of citric acid, and put plane parts in it. If no bubbles come, then just add more citric acid. 1/2 cup citrate to a gallon water - can use large HD or Lowes buckets for plane bodies. This works well for me. Rust scrubs off easily
What does it look like after scrubbing the rust off? I've never seen a before and after picture but lots of folks claim it works very well as does Evapo-rust.
 

Chris C

Chris
Senior User
I use a piece of 4 inch PVC pipe capped on one end for plane bodies....Made a little wooden box to hold it vertically. It doesn't take nearly as much liquid to cover.


I pour water in the half gallon milk jugs, stir in a 1/4 cup of citric acid, and put plane parts in it. If no bubbles come, then just add more citric acid. 1/2 cup citrate to a gallon water - can use large HD or Lowes buckets for plane bodies. This works well for me. Rust scrubs off easily
 
Last edited:

Chris C

Chris
Senior User
Thus my original question...

I see Evapo-rust online for $17-24/gallon. I don't know how much of your 5 lb bag would be used in a typical rust remover solution or how fast it will lose it's efficiency (3-4 times?).

Your Spicy World citric acid is about $17
 

Gofor

Mark
Corporate Member
Although it is difficult to translate weight to volume when measuring, based on the above statements, it takes about 1/2 - 1 cup of the citrus powder (4 to 8 ounces??) to 1 gallon of water for a good solution, so that would give you 10 gallons or more of mix. I doubt the mix would stay viable for multiple uses, so it would depend on how man times you could re-use the evapo-rust. I have reused Evaporust up to three times, but I have not used it extensively enough to really give a definitive answer.

Another consideration is the ability to use citric acid in other applications. It makes a very good spot remover for some carpets for example ("try in an inconspicuous spot first").
 

Chris C

Chris
Senior User
So I mixed about one cup of acid in about 3 gallons of water last night about 7:00 pm. This is what it looks like now... Bubbling away.

20200711_112732.jpg


Before...

20200711_113653.jpg


20200711_113557.jpg



After...

20200711_112922.jpg


20200711_112906.jpg


The pics don't do justice... The rust residue you see just wipes away.

I'm a believer.
 

MarkE

Mark
Corporate Member
Although it is difficult to translate weight to volume when measuring, based on the above statements, it takes about 1/2 - 1 cup of the citrus powder (4 to 8 ounces??) to 1 gallon of water for a good solution, so that would give you 10 gallons or more of mix. I doubt the mix would stay viable for multiple uses, so it would depend on how man times you could re-use the evapo-rust. I have reused Evaporust up to three times, but I have not used it extensively enough to really give a definitive answer.

Another consideration is the ability to use citric acid in other applications. It makes a very good spot remover for some carpets for example ("try in an inconspicuous spot first").
I have used a batch of citric acid solution to de-rust several several hand planes. It seems to last quite a while. If it starts to slow down, you can add incrementally more to the solution to get it going again. In my opinion, it is more economical than using a commercial product like Evapo-rust.

Another inexpensive option is electrolysis, although the startup cost can be high if you have to buy a power supply of some sort and/or an anode. I had a five gallon pail set up and used an old car battery charger for the power supply and an old lawn mower blade for the anode. It works great for large pieces, not as well for smaller items.

FYI, citric acid is also used to reduce the PH of homemade tomato sauce so it can be safely water bath canned. only need about 1/4 teaspoon in a quart. :)
 

Chris C

Chris
Senior User
I'd say about the same.

I put more parts in the solution to see how well it works on a second run. Just checked and it's bubbling away.

I didn't add any more acid to the bucket.


Looks good, but how does it compare to Evapo-rust?
 

junquecol

Bruce
User
Have you tried a soft drink? Coke removes rust, and I'm sure Pepsi would do the same. Two bucks a gallon (on sale.)
 

Jeff

Jeff
Corporate Member
I'd say about the same.

I put more parts in the solution to see how well it works on a second run. Just checked and it's bubbling away.

I didn't add any more acid to the bucket.
Thanks. The metal may still a bit pitted but that's not a surprise I guess. I wouldn't expect it to have a smooth and polished look like new.
 

Jeff

Jeff
Corporate Member
Have you tried a soft drink? Coke removes rust, and I'm sure Pepsi would do the same. Two bucks a gallon (on sale.)
Lots of soft drinks have an acidity (pH) similar to citric acid which is also used in the food and drink industry.


 

Our Sponsors

LATEST FOR SALE LISTINGS

Top