Technical Does anybody have a definitive "recipe" for mixing citric acid?

I think "Evaporust" and "Rust-911" are wonderful products, but a little expensive. I have heard that the main active ingredient in both is citric acid. I just purchased 5 lbs of powered citric acid from Amazon for $13.19. I think I saw on here that it is mixed with water and a little detergent (to act as a surfactant) to make an equivalent solution. Does anybody out there know how much of each ingredient should be combined to make an effective solution? If not, I'll do some experimenting, but it would be nice to know where to start.

 

I understand that citrus acid removes rust and evaporust is a rust converter.
Vic

 

I don't think so; I have used several "Rust Converters" (Rustoleum makes a good one), and they leave a black paintable surface. "Evaporust" leaves a clean raw steel surface (as does "Rust 911").

 

I've used 1 kg (2.2 lbs) of citric acid in my cooling system, which I got a local wine supply store. If you haven't gotten any oil in your cooling system, I have my doubts that an added surfactant would be necessary.

In my case, my cooling system holds 12.3 litres so the citric acid concentration was 1 kg / 12.3L = 8.13%. This had enough strength to make my engine's interior look freshly cast.

See Cooling System.

 

https://www.jalopyjournal.com/forum/threads/dip-tank.1079667/

 

What is the strength of the citric acid you bought? Are we talking 5% or 100%USP pure? This will change how you mix it.

Sent from my SM-G950U1 using The H.A.M.B. mobile app

 

Most Rust converters use phosphoric acid.

 

What Tubman bought was 100% pure. Actually food grade. I found it on Amazon but ordered a different brand. I'd like to know the preferred mix ratio too.

 

I'm sorry, but I don't see a thing about citric acid in that thread. This is NOT about molasses.

 

What's white vinegar acid content?.Might be a place to start, as it does a good job on rust when you soak it. Then again white vinegar may not be citric acid, I dunno, I'min school for Industrial Electronics, not chemistry

 

There is a thread a few years ago that was pretty good on citric acid.

https://www.jalopyjournal.com/forum/threads/rust-busting-a-new-way.849395/page-2

 

Actually, that was the thread that prompted my post. I have been through it, and there are mixture levels quoted anywhere from 1 lb to 1 gallon of water to 1 lb to 8 gallons of water. That's quite a range. I also saw the use of detergent as a surfactant on another forum, and it was mentioned in this thread, but in relation to using vinegar. Since both vinegar and citric acids are relatively weak acids, it looks like there may be something to the addition of detergent to the mixture. I just thought in the last 4 years this subject may have matured enough that a definitive formula might have been developed. This is just me being lazy and looking for the easy way out.

 

I buy the food grade stuff from Amazon in 5 lb bags. Looks like something out of Scarface...

Anyway, I mix 1 pound to 5 gallons of water and it works out pretty well for me. It eventually gets weaker with contamination. I use a smaller container, cat litter, for smaller parts and use an old pool skimmer basket to do hardware.

 

Just thought i would provide some info on an alternative if you did not find what your looking for.

 

NaOH. A very strong base. That will remove rust too.

 

Thanks for your input. That's the kind of information I was looking for. I also got my citric acid from Amazon. Let's see, at $90 for 5 gallons, "Evaporust"" is $18 per gallon; a gallon of "Rust 911" concentrate for $60 makes 16 gallons which makes it $3.75 a gallon. At your ratio, 5 lbs of citric is $14 and makes 25 gallons, which is a little over $2 per gallon. At a 1 lb to 8 gallons ratio (which someone the original thread said worked fine), the cost would be slightly less than $2 per gallon.

If I had my 'druthers, I'd use "Evaporust" all day, but at about $2 per gallon, citric acid looks like a reasonable alternative. Now if I can just find out about the added detergent....

 

I've always used vinegar with very good results. I was going to use a bigger tank with vinegar, but hadn't had time to set it up. Then the citric acid discussion started. So I bought a 40 lb bag of citric acid. Then I heard that the citric acid stopped working after a while, like a year later; which I never experienced with vinegar. So I've hesitated to start over with citric acid if it is going to go bad later. As soon as I get a bunch of stuff ready for the tank I'll set it up, to maximize the citric acid. As I know it now, citric acid might be a little cheaper, but I think that vinegar will last longer.

 

I soaked the front of my rusty '59 Ford hood a few months back. Let it sit for about a week in the bath. The rust came off very nicely.

 

I tried it a couple of months ago. Ratio wasn't too strong, about 3-4 ounces in a gallon. I gently agitated it, and took the rust out of the 34 Ford seat tracks I was testing in a few days. Nice thing, once it was rinsed, it didn't start to flash rust, like I experienced with the muriatic dip I did a few years ago.

 

So you're in the ballpark. 4 ounces per gallon would be 1 lb to 4 gallons, 3 would be 1 lb per 5 1/3 gallons. I see a pattern starting to emerge.

Now, who knows about the detergent?

 

Do you need to do a soda bath after dipping in citric acid? I did it after using vinegar to derust some parts to kill any acid left on the surface.

 

i have done many panels using a ratio of 10parts water 1 part citric and had great results in a short time frame...
also done some at 5parts water ..1 part citric and pretty much the same result.
depending on the rust build up it can take from 4 or 5 days to 2 weeks and on panels with a fold in them,as in double skin i think it best to rinse them in bi carb bath just to make sure they are neutralised so nasties when it comes to painting.....on some of the panels i did they had alloy attached and it did not seem to effect it....not that i recommend
it....after rinsing the panels clean they will flash rust so then i give them a wipe down with ranex and they are good to be stored in a dry place for ages....i have some that have been done this way 5 years ago and they are still clean

 

forgot to mention that it is easier to dissolve the citric in warm water then add to your larger tub.....and with the larger tub or whatever you use i have a length of plastic conduit that i squirt compressed air thru to agitate the tank

 

Lemme see; "a pints a pound the world around", so that means 1 lb of citric acid to 10 pints of water. 10 pints is 1 1/4 gallons, so it looks like you are mixing it much stronger than most of the others. Not being critical here, but trying to figure out what works for most people at the lowest cost. What kind of citric acid are you using? Maybe it's not as concentrated as the stuff from Amazon.

 

^^^ This. Citrus soak, yes. Agitate like described. Recommended 'soda rinse'...Baking soda mixture in a jar picked up by water velocity.
But...I use distilled white vinegar. Soak big Terrycloth towels in it, wrap the parts, then wrap the towels with PlastiWrap. Check in 24 hours, usually takes 36 for crankshafts, big stuff. Rinse with water, 'black' rust residue comes off with good water rinse and a sponge. Won't hurt the lawn. WILL turn driveway white.

 

don't have any at hand at the moment....but the citric i used was for cleaning the pipes at wineries and paid
25$ for 25 kilo bag (about 50lbs)
we had a lengthy thread on this topic in our local forum but have been unable to find it so far.
the overall strength of the mix from what i have worked out don't matter,just means leaving part in there longer or shorter amount of time

 

by Grazza on Sat Mar 18, 2017 6:21 pm

I mixed 10Kgs to around 300 liters of water. In and out with the rusty item in 2 days. Next lot went in and out in 2 days also, result just as good as the first. So far I have had 4 lots of stuff go through the tank and everything done in 2 days. Last couple of items have only been small - brake pedals, brake rods stuff like that. Mixture doesn't seem to be getting any weaker with use. When I did the '27 Tudor I did the whole body in one tank, bit at a time and noticed no reduction in results.
Graeme

 

:43 pm

With the citric acid, I found that a 25kg in a 1000lt ICB (big cube container, with the top cut out) of water is a good mix. Eg 40:1 = water in liters to acid in kilograms. Adjust the volume to suit the job, did inside a Ducati 900 tank recently and came up a treat using 1/2 kg in 20lt. When mixing in the ICB I just put in the bag and allowed the flow of the hose to mix it while filling up, and a little stir when full.
By the way, I've got acid for sale in classifieds....
Cheers, Dan.

 

Joe (or Graeme), thanks for the info. Hmmm. 10 kilos is about 22 lbs. 300 liters is roughly 320 qts or 80 gallons. 80 divided by 22 is 3. 63, so it looks like 1 lb per 3.6 gallons. I'm starting to see a pattern here. (Excuse the approximations; I want to keep the math simple.)

Just saw the latest post; 1/2 kg to 20 liters is about 1 lb per 5 gallons. just about what I'm seeing elsewhere. Excuse me for thinking aloud, but I want to get this straight in my mind.

What do you know about adding a little detergent? I just heard from a friend in Sweden that it helps break down what oil residue that may remain on the parts to allow the solution better access (for want of a better term) to the metal.

 

by ekdave on Sun Jan 15, 2012 10:32 pm

finally set up my 1000 ltr tank for de rusting the 41 chev
24 hours in the tank with 1000 litres and 25kg of citric great results

ng my scintific test on citric acid with various ratios of citric acid with water or vinegar
All tests have a patch of a rusty sun visor , all same size and same rust with No stamp and containers numbered
1st test was soaked for 25 hours , then rinced in clean water then scrubed with 3M dish washer pad

Test 1 350 ml water with 2gr of citric acid
Test 2 350 ml water with 4gr of citric acid = to 25 kg / 1000 liters
Test 3 350 ml water with 8gr citric acid
Test 4 350 ml water with 16gr of citric acid
Test 5 350 ml water with 20gr of citric acid
Test 6 350 ml water with 30gr of citric acid
Test 7 350 ml water with 40gr of citric acid
Test 8 350 ml white vinega
Test 10 350ml 1/2 water 1/2 white vinega with 8gr of citric acid
Test 11 350 ml white vinega with 8gr of citric acid

Day 1 results
Test 1 rust starting to move but least effective
Test 2 better than No 1 & = to No 8
Teast 3 better than 1 & 2
Test 4 better than 1,2 & 3
Test 5 better than 1,2,3 & 4
Test 6 better than 1,2,3,4 & 5
Test 7 Better than 1,2,3,4,5, & 6 almost clean
Test 8 = to test 2
Test 10 almost = to test 7
Test 11 = to test 5
Rusty patchs No stamped