Technical Evapo-Rust and/or citric acid questions

I'm going to try one (or both) of these soon to derust small parts that are either inconvenient to sandblast (bolts, nuts, etc.) or have places (cracks/crev***es) that sand won't get down into. I'm pretty tired of cleaning bolts and nuts with a wire wheel on a bench grinder. About 1 in 10 get thrown across the shop never again to be found. Also wire wheels are not finger friendly. I've been doing this my entire adult life and it's time to do something better/easier.

Question 1:

Do these evaporate if left in an open container? My plan is to buy new 5 gallon bucket(s) and lid(s) and just leave the liquid in sealed container(s) when not in use. Am I missing something?​

Question 2:

Does the rusty part need to be completely submerged?​

Question 3:

What, if anything, do I need to rinse the parts with when they come out of the solution?​

Question 4:

Will cold affect these? My shop is unheated. Even though it almost never freezes in there it does get mighty cold at times.
​

Queston 5:

I'm guessing these loose effectiveness eventually. Should I throw out the old and replace with new? Or can I just add more new?​

I've Googled and searched JJ, GJ, FTE, etc., and not found answers.

Thanx in advance folks.

 

As for citric acid, which is what I use, I will throw out my opinions. Question 1: yes, and a small container with a lid is how i keep mine for small parts. Question 2: Yes Question 3: I usually just rinse my parts with water and then blow dry them. I'll then apply some por15 metal ready and then dry them off again. Question 4: Yes. The citric acid works faster in warmer weather/water, but it will still work in cold weather. Question 5: There are only so many chemical reactions in a batch, so yes it eventually wears out. I have added more powder to an old batch before and it work, but I think you're better off to ditch the old and make a new batch. Hope this helps.

 

As I've posted before, I was a total skeptic of citric acid when I heard about it here on the Hamb, UNTIL
I tried it. To answer your questions:

1. Since you mix citric acid with only water, yes it will evaporate over time if left uncovered
2. Yes.
3. Clean water, thoroughly rinsed.
4. I have never had an issue with colder temps. I normally just leave the parts submerged
for 2-3 days. Depending on the rust, some parts take longer or shorter.
5. I usually mix it stronger at 2 cups citric acid to 3 gal. of water. I just dispose of it in the
sink or yard, and make up a new batch when needed. No reason you couldn't try to
save it. No harm done.

Here is a picture of my bumper ends, before and after soaking in a big tub for 48hrs...

 

Evaporust turns black when its dead, you'll know when it no longer works. Very good stuff, but Rust 911 is the same thing but cheaper. Warm is good, maybe run a heat lamp overnight ?

 

I left citric acid in a small container and the water evaporated, leaving crystals in the bottom. I put more water in and stirred it up. I think it'll be fine.

 

I think the above answers are what you need. I’ll just add I use citric acid and I’m always amazed. I use an old plastic tub with lid and just lay the lid on top. I add just enough water to completely cover the parts. The parts have a black coating on them after a few days when I remove them which I wash off with a hose and water and a brush, then blow dry. You could also rinse them with water and baking soda to neutralize the acid if you like. I’ve done both and haven’t really noticed a difference.

 

I have used evapo-rust on bolts and small rusty panels. Not cheap by any means but I pull parts to scrub them then re insert them into container several times to get rust off pieces. I use an old crock pot and set the temp to keep fluid warm. Works much better. Am going to try the Citric acid on some bigger parts.

 

Citric and oxalic acid take about the same amount of time, pretty safe, works great on chrome parts.

Phosphoric acid is faster (concrete / metal etch and prep at home depot) MSDS sheet lists it at 35-45% strength phosphoric acid.

Neutralize either with baking soda water to be safe. I just use dish soap - it's basic on PH and have not had an issue with it.

Part needs to be submerged or kept wet. On body panels, you can soak a towel or blanket and cover it with plastic to slow evaporation.

Evaporust - works great - pricey compared to other acid treatments.

Clean all you parts well before using acid treatments, it's not a degreaser, it'll just mess up your derust tank.

 

I have used evaporust on chrome vintage bicycle parts with great success. I have found it is much cheaper on Amazon than my local ACE hardware. it does not evaporate, it gets thick like pancake syrup. do NOT put it on pancakes. as stated it does lose effectiveness after a while. I would recommend that on ANY piece of rusty chrome. not good for paint though.

another thing I have used for rusty bike frames and fenders is oxalic acid, sold as "wood bleach" at the hardware store. you mix it with water, one $12.00 can is ebough to fill a kiddy pool and do a bike frame and parts. I did a very rusty frame and fenders just to see what it would do before I tried it on a bike I want to keep and it removed every speck of rust to the point I could have sanded it a bit and painted it with no rust worries at all. it is good for painted parts and most times won't harm the paint unless it is a candy color over silver.

a couple years ago I did all the hardware from my 1949 Chevrolet in one of those ********y tumblers. that worked quite well.

EDIT: on the CABE vintage bicycle forum, (the HAMB for bikes) it is recomended to not use Oxalic acid on chrome parts. it has some sort of effect on the chrome, not sure what it is.

 

I haven't used citric acid, but for Evaporust:

Question 1:

Do these evaporate if left in an open container? Eventually, yes. If you pour it out in a pan or something for derusting the parts, when done pour it back in the jug and close the lid. (if the parts are dirty or greasy, clean them first before putting them in the Evaporust. If the rust is heavy, or loose and scaly, it's not a bad idea to wire brush them first to get the big chunks off.​

Question 2:

Does the rusty part need to be completely submerged? Yes. If the part doesn't fit completely in your pan of Evaporust, after cleaning the first half you can turn it over to submerge the rest of it. Another thing I've done with parts too large to put in a pan is to soak paper towels in the Evaporust, wrap them around the part, and then cover the paper towels with Saran Wrap to keep them from drying out.​

Question 3:

What, if anything, do I need to rinse the parts with when they come out of the solution? Rinse in soapy water. You'll probably want to scrub the parts a little with a Scotchbrite pad to get rid of the remaining black deposits.
​

Question 4:

Will cold affect these? It can freeze, so store it in a conditioned space.
​

Queston 5:

I'm guessing these loose effectiveness eventually. Should I throw out the old and replace with new? Or can I just add more new? Throw it out when it stops working and get a new jug.​

 

My go to for little parts these days is white vinegar. Use it full strength or dilute it. Cheap and easy to find. It may take a little more time for the same results but worth your time to try it. Also good for wiping off flash rust as well.

 

I was told that Rust 911 is just as effective, as Evaporust
A gallon is concentrated, and will make many many gallons.
Leave stuff as long as you like only attacks rust.
A lot easier on the wallet.$$
I've used it on hardware, tools, and a large fender brace,
Beautiful results

 

Vinegar or citric acid is my preference..... citric acid has no odor, though, so it's less obnoxious.
Degrease first with Dawn or cheap oven cleaner.
Rinse, rinse in a Dawn bath, blow dry.
A crock pot or small submersible pump (fountain or aquarium pump) will speed the process.

These also work great for removing mill scale (which takes some effort to grind off due to its hardness) on hot rolled steel!

 

For parts too large to submerge, make some sort of a "pool" or collection area where water can drain and collect. Put down a pallet or something to keep the piece slightly elevated. Now the set piece on the pallet. Build a tent around and over the piece with all outside of the tent set to direct water back into the pool area. Fill the pool area with your de-rusting agent of choice, Evaporust, Rust 911 or oxalic acid. Set a sump pump in the pool that has the garden size hose attachment, not the large discharge hose.
On the other end of the hose set up a sprinkler. Set the sprinkler so the water is directed to get into all the cracks and crevices. Now turn it on and wait.

 

I've used citric acid quite a bit. Most of your questions have been answered, but maybe I can add a thing or two.

By the by... you'll have better luck with your searches if you use Google instead of the search function here.
Search "hamb citric acid".
Or "hamb rust removal".
All kinds of threads.

You don't absolutely have to cover it. Plenty of reason to, though... keep animals out of it, keep the odor in it. But I've de-rusted large parts in a large tub of citric acid left outside with no lid and it was fine. Might evaporate a little, but then it rains and fills it back up LOL.

Buy your citric acid online. Better price and besides, it's hard to find in the stores, especially in any quan***y.

It leaves a black residue on the surface of your parts. Gets on your hands and stuff. Comes off fairly easily, though. Power wash, soap and water and a brush or a rag, whatever.

It's not a super strong acid, but an acid nonetheless. So it's good to neutralize with a water and baking soda solution. Dip your parts in it, and mix some baking soda in your rust removal solution before dumping it on the lawn.

Don't be afraid of it. Simple process. Not a real fast process, but with enough time, completely thorough and won't hurt your parts. You'll be happy.

I've used it on chromed parts and I don't see that it affects the chrome at all. I've heard you shouldn't use it on machined surfaces. Might take a few molecules off that you wanted to stay on there.

It can change the color of paint but I haven't seen it take it off.

Have fun. Good luck.

 

Oh, as you might guess, it does nothing where there's grease. Degrease, then de-rust.

 

It's been asked, what's the best rust removal process? I always say, all of them.

Depends on the type of part and the results desired.

A single process will usually do it, but...

I've sandblasted, then acid dipped, and then sandblasted again.

 

I only ever use white vinegar. Leave it to soak for about a week

 

Evaporust does evaporate if you leave it in an open container.
I did this old chain when I was seeing how it would work a couple of years ago. This after soaking it in Evaporust overnight. I forgot to take a before photo. It leaves an iron oxide coating on the part.

I dump it back in the jug after I use it and just use a plastic pan from Dollar Tree to soak stuff in but a plastic container with a sealed lid might work better.

I have rinsed pr wiped part off after I took them out but just let the chain dry.

I have a box of citric acid that I have been wanting to try but have the same issue with cold weather. Mice may have eaten it where I had it stored though.

 

I use citric acid. I have used it in large bins for large parts, smaller ones like old cat litter vessels with a strainer basket for small parts and hardware. I use a mix of 1 pound per 5 gallons of water and it seems to work fine. I rinse with baking soda and water.

The biggest thing I did was the front of my Ford hood. I used an under-bed storage bin, stood the hood up on my deck and lashed it to the railing. Anything I have done took a few days to work. Once the mix gets funky, I toss it and mix up a new batch.

Any residue left comes off with a nylon or wire brush. I have done coil springs, control arms, etc as well as small parts like brackets.

 

Nuts and bolts in cleaning vinegar here. Hardend steel springs for carb throtles or other sorts of small springs can,t just stay in your bucket for weeks, they get eaten up. Same for pot-metal parts. Pot-metal can be destroyed in a matter of hours, you see bubbles first . Don,t mix copper or br*** parts with steel parts, the steel colour stays on the copper/br*** and then you have to scrub and polish. So for copper/br*** best to use clean vinegar .

 

I just did a windshield frame in Citric Acid , actually it is still in the bath.

Used some wood I had and a contractor garbage bag for the container. Here are a few pictures

 

Vinegar is an acid. It WILL eat the steel if left long enough. I ruined a small pocket knife doing so.

Ben

 

hey, we're both into vintage bikes like most things on CABE, one way or the highway.
I prefer oxalic on chrome, there is a yellow cloudiness that can develop if the mix is strong or left in too long, stir the acid bath and wipe the part down as it's soaking and it's not an issue. I've run dozens of frames thru oxalic acid. Started using citric recently, I see the same yellow reaction. Both oxalic and citric are simple to find - the bike guys get extremely defensive on which one is best. I've used both - they're both fine.

 

Here's a couple before and after Evapo-rust, a mildly used 5 year old 5 gallon bucket. I hang parts with bailing wire from the edge of bucket. A week of soaking, scrubed with a stiff brush & comet, then gone over the wire wheel on grinder.

 

I've used Evapo Rust. It works well, but I've found that plain white vinegar works just as well (removes rust quickly, environmentally friendly) but it's 1/25 of the cost and you can get it at any grocery store. $2-$5/gallon.

 

At one time there was lots of information here about using mol***es from the feed store, diluted 90% with water. There was concern about changing the composition of the metal; maybe the concern was hydrogen embrittlement. There was one comment about using vinegar to derust an old license plate; that person left it in the vinegar too long and it disappeared.

 

Thanx nomad. I've used vinegar and mol***es and am hoping for something better.

Between vinegar and mol***es I liked mol***es better.

 

Mol***es works great but the smell can get pretty nasty after a while. My grandfather would bring barrels of it home from the sugar plant to put on cattle feed along with the beet tops from the sugar beets that those cows loved to eat back in the 50's and 60's and if it sat out for a while it got pretty bad smelling. Not something you want in your garage.

 

Cattle-feed-type mol***es works because it has CITRIC ACID in it.

But as @Mr48chev said,
It's pretty stinky.

People got smart and started using pure citric acid.