Ok - last weekend I scored a box of miscellaneous small parts, some in better condition than others, but there were a lot of parts all the same. Which got me to thinking - what is the best way to clean and restore small metal parts, given that sooner or later some parts may just not be around anymore.

So I retired to my lab and set up an experiment

First I found three groups of items that were as equally rusty or degraded as each other.



Some BB cups


Stem Bolts (black oxide finished)


Bearings


Here's the products I decided to soak them in












The measured dose of each



In go the parts

Note the effervescence of the Phosphoric acid almost immediately!




Here they all are after half an hour

Slight bubbling in the Lemon Juice


Small bubbles in the vinegar


The OA seems quite stable


The Phosphoric acid is quite active





After five hours all containers were lightly agitated and lids with holes in them were placed on top to try and avoid any evaporation.




24 hours later they looked like this











All containers were flushed with water until they ran clear



The only cleaning implement I used was this, no heavy scrubbing, just a wipe down and slight scouring to remove residue




The items were dried in paper kitchen towels

And now for the end results...

Lemon Juice






Vinegar






Oxalic acid





Phosphoric acid

Great write up Ben. Love the details and the results speak for themselves.

Cool experiment!

Lemon Juice? I had no idea...

The price of lemons is about to go WAAAY up!

Damn, I didn't think the lemon juice would do anything!

Should have used a cup of coca-cola too.... that stuff eats rust like nobody's business.

http://www.wattyl.com.au/library/MSDS/Exte...%20Aug%2005.pdf

I don't wish to blow your experiment up, because I think it's great! But you neglected the most important factors. 1. Strength of solutions 2. time of dip, and 3. reactivity of the materials involved. You must either; A. adjust your solution strength to the time of the dip (24 hours), or, B. Adjust your time of dip to the strength of the solution. 3. Change the materials in the reaction. Your results will change dramatically.

According to the MSDS, that solution of OA you are using has a PH of 1.3 right out of the bottle. That is a wicked strong mixture of OA. That is a severe skin burn hazard at that concentration. Just as the MSDS shows. 24 hours at that concentration will cook things to bits, and it did!

Cut that solution of OA you have down, with about 20 parts of water to one part of OA solution you have, ( for starters ), since we have no idea how much is really in there, other than the PH of 1.3, and dunk some more parts for 24 hours. And wipe them with a tooth brush every 4-8 hours. And take them out if the rust is gone before the 24 hour timer goes off. (Hence the preferred use of crystals, you can control the mixture, and know where you are starting from.) Your solution is probably about 20 times the strength you wanted. (off the cuff, guessing from the looks of the parts)

Anytime you are using things that potent, you need to get them out of there very quickly, or they will blacken things, and even remove the nickel plating. Which I can see the nickel and even chrome has been stripped from the bearings here in more than one photo. The fast results, and strong mixtures, are never as good as the slow soaks. The bubbles in the OA and in the Phosphoric Acid show WAAAAAY too much activity, especially the later. That is to the point of major chemical reactions, and plating stripping going on there.

When the OA is mixed correctly, it should look exactly like the Vinegar photo after about an hour. A few bubbles on the surface of the parts. Even the lemon juice has way too much going on there.

Concentrated Lemon juice has a PH of about 2.3. Which means the OA solution you were using was exactly 10 times more acidic than the lemon juice, as the PH scale is logarithmic. So you would need to dilute it 10 parts water to 1 part of your solution just to get it down to the PH of the lemon juice, and dilute it even more to get it to the PH of 3 of the Vinegar. And with OA, it doesn't need to be even that strong.

Here is another one for you to try. Sour Salt. Pure citric acid crystals found in the Kosher section at the grocery store. We found a box of it cleaning our 30 year old beer can collection out of the basement a few months ago. Along with vintage glass bottles of Real Lemon Lemon Juice. Sour Salt is pure citric acid pellets for cooking. But I know exactly what you are going to find, but find it out anyway, it's all good. Here again, for small parts it will indeed remove rust. So will Coca-Cola, But filling a bath tub, or pickle bucket full of Real Lemon Lemon juice... is not practical.

I don't care what the chemical is, it's not really about the chemical at all... , it's about the strength of the solution, and the time exposed, and the reactivity of all elements within the chemical's environment to that chemical . You can get phosphoric acid so strong that will burn your skin off instantly, and at the same time, I just took a sip of Phosphoric acid, in my Coca-Cola. You can't just buy stuff, and pour it in, and arbitrarily set the timers all the same. That Phosphoric acid solution went to work violently stripping the nickel and the chrome off of the parts, as shown by the bubbles. (reaction). The plating is all cooked off. Way too potent, and Phosphoric Acid goes after nickel too, not just the rust.

Nitric Acid, Hydrochloric Acid, and Phosphoric Acid will all take rust off. However, those 3 chemicals are also what the platers use to strip chrome and nickel off of parts.

Dilute that Phosphoric Acid you have down by about 20 to 1 or maybe even 50 or 100 to 1, Maybe even 200 to 1 with that, and try it again. Your results will be vastly different.

Mild solutions are what is needed. Mild, mild, mild.

...Then you will start discovering a whole different set of test results. For example, do you see how there is still rust on the threads with the lemon juice? That is common. It works great on the surface rust, but for what ever reason it tends to get used up, and loses it's oomph rather quickly, and the bigger and deeper stuff often gets left behind. (One of the reasons we quit using it way back when) ...Unless you keep adding more fresh stuff. But it works pretty good for long soaks on small parts without any major corrosion.

...Then you will also discover that the OA just keeps on taking layer after layer of rust, slowly, until it's gone. But too long, with only nickel, and no chrome, and you will see it start taking the nickel too. But with weak concentrations, you can watch that exact point in time, and pull the part out when it's done just right.

The phosphoric acid works well too, but really goes after the wrong things, even at low concentrates.

Vinegar, I think it just plain sucks in many ways, because it too loses potency quickly, but goes after the wrong things too, and ....I really don't like the stuff for this purpose. But, the fact is, the Vinegar, and the lemon juice are the only two that had appropriate concentrations of solution for your test.

Try this.... Pour some Coca-Cola into a cup, and test that. It will take a while, but you will discover some crazy stuff. And that is at a concentration which you will drink. (If left long enough, it will eat the rust, eat the nickel out from under the chrome, then eat the steel, and in time, with some fresh Coca-Cola added once in a while, will dissolve the whole part, but don't take my word for it, try it.! ) (Take one of your kid's baby teeth, and put that in a bottle of Coca-Cola, the tooth will vanish in a month or 2....) lol.

Cheers,

Keep going... more testing is better testing....



BTW, since photos are good, I have been goofing around with stuff myself lately. I am dealing with getting rid of 1500 beer cans. Here is one I goofed around with last week.


This was a couple of lumps (few tablespoons max?) of OA diluted in 5 full gallons of water in a pickle bucket. Filled with other rusty cans. Filled 3 times with rusty cans, and this was in the 3rd load, 18 hour soak. (just messing around for old times)










But that would be the starting point for a restoration, and preservation. It also shows how OA plays nice with paint. A hint here. If you used Lemon Juice for this can, with this quantity of rust, it would take the whole bottle of juice, and it would take longer, and the juice would stop working after only a can or 2 like this, leave alone load after load with a bucket stacked 2 layers high full of them. (But seriously, figuring all this out is what we did way back when, trial and error.)


But, If you want you can see how worthless these cans are, and see why our VBMX parts are time better spent on restorations... Any why I didn't do it up right... This is the first batch of many, and I will get... ? 20 bucks? lol.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...=STRK:MESELX:IT


I totally want to see some more experimentation going on here, and as always, love to see it!

But I needed to point out that what you are showing is how NOT to use Phosphoric Acid and Oxalic Acid with those results. The Lemon Juice, and Vinegar was exactly as I expected to see. You just burned the parts up with too much chemical on the other two, for too long of time, in those photos.

Really rusty stuff is another good topic for your experiments too...

T

Done this a variations lately and it is a trip. the chemical reaction will actually start a current. I recommend having your kids watch

Great thread contribution. Ted Carl is correct, but it's still a great effort.

Lemon juice is a favorite of mine, I recently tried vinegar for some hex bolts and got good results as well.

Um, Gasoline after a good soaking, seems to allow for nearly immediate cleaning of rust. Gas will not compromise any of the material and you can just leave parts in it forever.

The longer you leave them in ( 1-2-5 days 1-2-5 hours) the newer and shinier they are when they come out. You can just swish the parts around in a container and they self clean and rust just falls away.

Anyway...

Hi Ted and thanks for your input.

You have pretty much summed up the conclusion of the experiment when you say "you are showing is how NOT to use Phosphoric Acid and Oxalic Acid".

I'm a big fan of OA and use it regularly in granular form, in a fairly haphazard manner ie: sprinkle a bit in and see what happens.

One of the reasons I carried out the experiment with these products is that it was reducing the variables, I know exactly the amount of OA in the mixture (100gms per litre), the same with the Phosphoric Acid (345ml per Litre). The reduction of variables such as weights and measures allows myself to rely on the accuracy of the solution use, along with others that choose to use replicate whichever method they prefer. I purposefully avoided using any powders that would require mixing so as to remove any variation, the products I used are all available off the shelf in Australia and required nothing else but to be poured into the containers.

We now know that at that level the OA is far too strong and/or possibly the parts were in the mixture for twice as long as they needed to be. But we do know one thing is for certain and that is if we repeat the experiment the result would be the same. Not meaning to sound rude but replicating a mixture of "... a couple of lumps (few tablespoons max?) of OA diluted in 5 full gallons of water in a pickle bucket" consistently may cause some problems (sheesh as an Aussie I have no idea what a pickle bucket even is )

You are also correct in saying the phosphoric acid was way too harsh, it ate so much of the metal that the bearings simply fell out!

What was I really trying to achieve was show people the relative efficacies of the individual products under controlled situations with as few variables as possible. Rather than neglecting the important factors of 1. Strength of solutions 2. time of dip, and 3. reactivity of the materials involved, the experiment illustrated as a result the ultimate necessity to control these factors.

My hope was that people will see clear evidence of what happens when you know categorically the strength of the product you are dealing with, not champion one above the other.

So, in conclusion I totally agree with you when you say "I don't care what the chemical is, it's not really about the chemical at all... , it's about the strength of the solution, and the time exposed, and the reactivity of all elements within the chemical's environment to that chemical" and this experiment has proven that.

Absolutely.

It also shows the importance of experience. And the importance of test parts.

If a part is important to you, do some test parts first.

Once you have a solution dialed in, and a time dialed in, it's much easier. But, that only comes with practice, or by doing some test parts. Then you have it licked.

I always like to remind people that it took 2001 tries to make a light bulb, the first 2000 could be viewed as failures, but were considered successes, because 2000 ways were discovered of how not to make a light bulb, using those materials. So if you know it's possible to get good results from a materiel, and you are not getting good results, one needs to look at what they are doing wrong in the process, not necessarily what is wrong with the material.

FWIW, a pickle bucket is your garden variety 5 gallon plastic bucket, that holds 5 gallons of house paint, or drywall compound, or driveway sealer, or .... pickles when they are delivered to restaurants. Once they are empty, they tend to be called pickle buckets here, because if you need one, you don't go to the hardware store and buy 5 gallons of paint, and dump it out, you go to the restaurant and they will give you as many as you want...

So, oddly, one can use up their supply of drywall compound, and wash out the bucket, and strangely, it magically becomes a pickle bucket.

Good stuff.

Great Thread! Thanks to all for sharing your time and effort. I have a few old parts that need restoring and rust removal. This will help so much.

BTW, I discovered that you have to make sure that the baby teeth have fallen out on their own BEFORE you try any expierment.

Dan

Nice work Ben. It's always good to see someone checking out several different methods of rust removal and documenting it all so clearly. Excellent presentation...

The more methods researched, obviously the more we can get a better understanding of what works better than older, nasty or toxic ways.

From what I see in your pictures, the Lemon Juice clearly had the best outcome.

Bottom line, the best product to remove rust should ultimately be the least poisonous, cheapest, most easily available and least damaging to your parts.

Again, in your test, that would clearly be the Lemon Juice.

BTW, if you like the Lemon Juice results, want to easily control the pH from mild to strong at any time and save big cash, go for Citric Acid Powder in bulk form. Pound for pound it's the safest, cheapest and most effective too.

3/4 of a cup of CAP per gallon of water works very well and is quite mild... It won't "cloud" up parts with any nasty staining or even begin to remove anodized finishes in under 24 hours.

Here's an awesome supplier of CAP for less than $4.00 (US) a pound including shipping:

http://cgi.ebay.com/10-lb-Anhydrous-Food-G...0#ht_1228wt_941

If you have any Citric Acid Powder left over, you can use it to make all kinds of food and drinks not to mention countless other uses including tenderizing game meat and making bath balms!

That would be very hard to say for any of the other stuff!

Again, nice work Ben.

wow the lemon juice worked great on the bb parts, awesome never would have thought of that.