CITRIC ACID: Suggested Utilization techniques
By Tom Chegash. This article is dated 21 April 2006
INTRODUCTION .
Hi, I'm Tom Chegash; Alias “Candog” or whatever anyone calls me at the time. (Usually just “DOG”), you will find me on the newsroom message board periodically. Well, I have been asked many times to do this article, and I have written up pieces of it in Rustlings a couple times, but I think this might be a good thing to add to the website for all interested can dumpers to read.
If you can't decide between using Oxalic acid or Citric acid to soak your rusty gems you'll have to make up your mind on your own, I'm not going to try and sway you, (well Ok I will.) However, I do get my drawers in a wad when Oxalic users say that Citric doesn't work. That is just plain wrong! Anyway, supposedly there is an article coming on the use of Oxalic acid, and hopefully we will be able to offer advice on both methods; you'll just have to determine what's right for you.
When I started using citric years ago, there was a raging debate going on in the BCCA about the health risks of using Oxalic. (The RB did not exist then.) I don't know the real truth about one or the other, but I had very young children at home, and I was not going to chance using what I knew to be a toxic agent around the house. You can do your own research on Google now, so I don't need to go there. The Material Safety Data Sheet for Oxalic can also be obtained at http://www.jtbaker.com/msds/englishhtml/o6044.htm it is hazardous. On the other hand , Citric acid is recognized as safe for use in food by all major national and international food regulatory agencies. It is naturally present in almost all forms of life, and excess citric acid is readily metabolized and eliminated from the body. Contact with dry citric acid or with concentrated solutions can result in skin and eye irritations, so don't get it in your eyes, and wear gloves if you have a cut. I usually wear a protective apron, and use padded tongs to handle the cans. Oh, by the way there is no MSDS for Citric Acid!
HISTORY.
Now, I've been using citric acid in one form or another since 1981 when I started collecting and dumping. So I have about 25 years of experience using this stuff. At first I used concentrated lemon juice as it was just .75 a quart back in the early 80's, but as the cost went up to $2.75-$3.00 a bottle I started looking for the powdered form. When I moved to Chicago in 1993 I discovered "Sour Salt" (this is a kosher seasoning) which could be bought for $2 a bottle. One bottle (like a seasoning bottle) would clean one load of about 40 cans. There were 4 oz in that bottle, and that's where my initial use measurements came from; 4 Oz of Sour Salt in 2 Gallons of water. Later, as I did more dumping I was buying out the food stores of all their sour salt and the sour salt became harder to find. So in 1995 I finally made the transition to buying citric acid in bulk, after I found a source for supply. I prefer the powdered form as it dissolves easier and more completely. You can purchase it from www.chemistrystore.com and you will usually get the powdered form.
Now, there are really two types of Chemical Citric, powdered and crystal form. The powdered form is very fine, finer than iodized salt; the crystal form will have granules larger than salt. Be sure to determine which type you are using. Either type works just fine, but if you get the crystal form you need to make sure the crystals are completely dissolved BEFORE putting your cans in the solution. You also should not add additional Crystal Citric as it will not readily dissolve in cool water. This is a major difference in the use of the two chemical solids, so please remember this tip if you get the crystal form shipped to you. To dissolve the crystal citric try using a cooking pot, boil the water on the stove; dissolve the citric in the pot, then pour the water into your soaking solution. This seems to work best for crystal citric. Powdered citric does not have this issue.
GETTING STARTED.
Now if you only have a couple of items to clean or are just getting started and you don't want to spend bucks on a bucket of citric acid (from $3 to $1.40/lb), then I suggest trying concentrated Lemon Juice first. Use the cheap lemon juice (store brand) as REAL LEMON can get expensive. The mixture is 1 quart of lemon juice to 1-1.5 gallons of water. If you need less water to cover the item, then reduce the amount of lemon juice by the appropriate amount. What I used to do is place the cans in hot water until they are just covered, then dump in a bottle of room temperature lemon juice.
A lightly rusted item would only need to soak for an hour or two; a heavily rusted item could need to soak for up to 24 hours. You can check the can while it's soaking for the level of rust removal if you want. After an hour or so take it out and use a soft toothbrush under warm running water and brush off the rust, rinse the can off, and place it back in the lemon juice if it needs to soak more. I would suggest keeping notes for yourself, so you can determine soaking times and cleaning levels for various stages of rusty cans.
CITRIC ACID.
( The remainder of this article will deal with the powdered form of citric.)
If you have used Oxalic Acid in the past and are trying Citric for the first time please be aware that the two methods of use are different. I think that Citric cleans cans better. That is my opinion, and I also contend that if you get bad results with citric, you are using too much acid, too hot of water, or leaving them in to long or not long enough. Remember, you need a lot more Oxalic Acid than you do Citric Acid, but Citric cleans slower. There is also a modification of the technique needed for silver crowntainers.
So why use citric instead of oxalic acid? Well, there are no fumes to inhale, you do not need to worry about ventilation issues, citric acid is used in many different foods and drinks so there is no immediate danger to children, (I would not put the stuff on my tongue though!) We know that citric will not kill the bacteria in your Septic tank, so there's no need to neutralize the acid before you dump it down the drain.
What is the danger in citric? Well as a powder it will sting like heck if you get it in a cut on your hands. The same goes for the dissolved liquid. The powder, although not likely to become airborne, can sting if it gets in the eyes, and it will make you cough if you breath it in powdered form. Once it is dissolved, the fumes will not hurt you, but it will stain things yellow over time, and it does smell after a day or two. (after a week it will get moldy!)
USE:
First; always pre-clean your cans before soaking them. Get the excess dirt, leaves, mice, and ants out of your cans, and brush the excess rust off of the outside. For this I use nothing more than plain warm water. No soap, no cleaner, and I do not try and scrub the rust off of the can; just clean off the dirt. Place the pre-cleaned cans off to the side when you are done. (Don't sink them yet!)
The mix of acid to water ratio should be less than 1/4 cup of Citric (about 2-3 Oz) to a gallon of water. Using more acid will not clean any better. You will just be dumping unused acid down the drain. With this ratio I can clean 60 mystery cans with about 8 gallons of water in a 12 gallon cooler using no more than a level cup of citric. Other ratios I have used: 1 teaspoon of citric for a single can soaking in a small candy jar; 2 teaspoons for 4-5 cans in a small cooler; ½ cup of citric for 30 cans in a medium cooler….you get the idea.
I use hot tap water at about 120-125 degrees. I run the water into a cooler with a lid pour in the acid, mix it up so it is dissolved, and then sink the cans. After sinking close the lid, and let it go. I soak heavily rusted mystery cans for 20-24 hours; readable cans for 4-6 hours, lightly rusted dumpers for 1-2 hours. Now if you are just cleaning a little rust off of a good can, use a smaller container, "warm" or “cool” water, and watch it while it soaks! Just like Oxalic! You can use citric in COOL water too! Silver crowntainers will clean in citric using cool water from the tap. The crowntainers may need to soak a full 24 hours. I would use warm-cool water for Metallic cans too, if you are worried about it.
One thing citric does exceptionally well is clean seams and rims. If you like rusty looking rims and seams use oxalic, if you like your seams and rims cleaner use citric. I think part of the issue is if you use citric you MUST scrub off the seams, lids, and rims and that's a little more work. Whenever I trade for, or buy a can that is cleaned in Oxalic, I always re-soak them in citric (for a couple hours) and the rims and seams always come out cleaner. One thing I have discovered with powdered citric is that you can only get 1 soaking out of a batch of acid if you are soaking mystery (heavily rusted) cans. Also, because citric is a bio-chemical, sometimes if conditions are right, you can get fungus like growths on the lids. Why this happens I don't know, but they scrub off fairly easily. I have never seen these small growths on the labels.
That's pretty much it. The rule is “Less acid, more time”.
Once again its personal preference and I would take home those bad dumpers to experiment with citric. The citric will not clean as quickly, that is true. However, you will use less acid, which will save you money in the long run.
From Dave Wheaton: All I can say from personal experience is that hot acid in heavier concentration works great on many standard-issue dumpers...but never, NEVER go hot and heavy on indoor cans - particularly those done up in metallic. Weak and cool is the name of the indoor game, if you even want to risk it. Metallic's often bleach and fog with acid treatments, so watch the concentration and duration CAREFULLY.
My note on this is that indoor cans will sometimes have been waxed by a previous owner or dealer. If you sink waxed cans into HOT acid, the can will fog up and appear to loose its color. This is not the fault of the acid; it is because of the hot water! Sometimes fogged up cans will come back on their own, sometimes they won't. They only way I have found to un-fog the cans is spray them with an acrylic spray paint. Usually the color comes right back. WD-40, Vinyl sprays, more wax, does not seem to work.
CANDOG