Cleaning Brass Using Citric Acid
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Dframe
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I've used citric acid for years but only on really dirty stained brass. As others have recommended, I just put a couple of spoons in a quart, soak and shake. I remove the brass, spread on paper towels to dry, and use another paper towel to wipe off any residual stains. Great product for extremely dirty or stained brass.
ironworkerwill
Member
I sure that them Alabama hillbilly crank cooks don't have any chemistry hours- they seem to do fine.
Elkins45
Member
THere's a product called LemiShine that you can buy in the grocery next to the dishwasher detergent. It's essentially citric acid with a little lemon scent. It does a fantastic job...just drop a couple of spoons into a gallon of water. Proportions aren't at all critical, but lower concentrations can be compensated for by increasing temperature or time (or both).
JackDaniel
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Where is that coming from??? The OP asked a legitimate question for help in solving his problem. Several experienced members came to his aid and that is what THR stands for. By your own admission all you brought to the table was sarcasm.
“…get a life…“ What kind of life do you have putting people down for no good reason? Not one that I would want.
Unclenick
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And I'm very late to this, but it came up on another board, and I found this thread and am not sure the OP ever got a concise answer to his question.
In general, in chemistry, all percentages are by weight. This is because the bulk density of powders are not necessarily consistent. This is due to differences in grain size, moisture content, how much vibration it was subjected to in transport, etc. Anyone who has seen the effect long drop tubes have on stick powder packing in a case will appreciate this.
In cool weather I like fresh bread with dinner, and since my wife hates the effort, the task of making it falls to me. In doing some research, I read an experiment by a cooking science laboratory in which 18 different cooks each scooped one cup of flour, all using the exact same tool and scooping technique: pushing a flat top measuring cup with a handle down into a bin of flour, then raising the heaping cup out and then scraping the top level with a spatula. The flour from each cup was weighed, and the extreme spread in weight was 13%. Just how hard or fast someone ran the cup down into the flour made that much bulk density difference. So, volumetric measuring just isn't precise.
That said, the citric acid level in the arsenal formula is, as mentioned by others, not critical. 5% makes a reusable solution that will do a lot of cases, and if it's 4% instead, it will still do a lot of cases. I also add a squirt of Dawn dishwashing liquid to the 5% solution to help suspend dirt. But citric acid by itself is a good water softener (neutralizes dissolved calcium carbonate pretty neatly) so the detergent may be doing more to make me feel good than anything else. I really need to run some side-by-sides to see.
A formula:
Basically, a gallon of water at room temperature weighs 8.343 lbs, or about 133.5 ounces. But wait! Isn't a gallon 128 ounces? It is 128 fluid ounces by volume, but a fluid ounce is the volume of one ounce of boiling hot water, at which temperature water is less dense than at room temperature. As a result of the density difference, a fluid ounce volume of room temperature water will weigh 1.043 ounces on a scale; and those are the ounces that matter.
Divide 133.5 ounces by 19 to get the amount of anhydrous citric acid you will need to dissolve in a gallon of water to make the combined solution 5% citric acid by weight. That works out to 7.028 ounces. 7 ounces is more than close enough.
So, what is the volume of 7 ounces of anhydrous citric acid? Per what I said earlier, this will vary. All I can do is report the weight of anhydrous citric acid powder I have, as I scoop it and level it from the 10 lb box I bought. A half cup (4 fluid ounces) of the powder weighed 3.83 ounces. The bag is mostly powder with lumps that are not very hard to break up, so it has a bit of moisture in it. I am not set up to do a titration to determine exactly how much moisture, so that just has to be part of the normal error. It would take 7.31 fluid ounces of my powder to get 7.00 ounces by weight. Given the non-critical nature of the mix, if I didn't use a scale and was forced to use volumetric measures, I would just measure 7 fluid ounces of the powder out (1 cup minus two level tablespoons), and add that to a gallon of water.
In general, in chemistry, all percentages are by weight. This is because the bulk density of powders are not necessarily consistent. This is due to differences in grain size, moisture content, how much vibration it was subjected to in transport, etc. Anyone who has seen the effect long drop tubes have on stick powder packing in a case will appreciate this.
In cool weather I like fresh bread with dinner, and since my wife hates the effort, the task of making it falls to me. In doing some research, I read an experiment by a cooking science laboratory in which 18 different cooks each scooped one cup of flour, all using the exact same tool and scooping technique: pushing a flat top measuring cup with a handle down into a bin of flour, then raising the heaping cup out and then scraping the top level with a spatula. The flour from each cup was weighed, and the extreme spread in weight was 13%. Just how hard or fast someone ran the cup down into the flour made that much bulk density difference. So, volumetric measuring just isn't precise.
That said, the citric acid level in the arsenal formula is, as mentioned by others, not critical. 5% makes a reusable solution that will do a lot of cases, and if it's 4% instead, it will still do a lot of cases. I also add a squirt of Dawn dishwashing liquid to the 5% solution to help suspend dirt. But citric acid by itself is a good water softener (neutralizes dissolved calcium carbonate pretty neatly) so the detergent may be doing more to make me feel good than anything else. I really need to run some side-by-sides to see.
A formula:
Basically, a gallon of water at room temperature weighs 8.343 lbs, or about 133.5 ounces. But wait! Isn't a gallon 128 ounces? It is 128 fluid ounces by volume, but a fluid ounce is the volume of one ounce of boiling hot water, at which temperature water is less dense than at room temperature. As a result of the density difference, a fluid ounce volume of room temperature water will weigh 1.043 ounces on a scale; and those are the ounces that matter.
Divide 133.5 ounces by 19 to get the amount of anhydrous citric acid you will need to dissolve in a gallon of water to make the combined solution 5% citric acid by weight. That works out to 7.028 ounces. 7 ounces is more than close enough.
So, what is the volume of 7 ounces of anhydrous citric acid? Per what I said earlier, this will vary. All I can do is report the weight of anhydrous citric acid powder I have, as I scoop it and level it from the 10 lb box I bought. A half cup (4 fluid ounces) of the powder weighed 3.83 ounces. The bag is mostly powder with lumps that are not very hard to break up, so it has a bit of moisture in it. I am not set up to do a titration to determine exactly how much moisture, so that just has to be part of the normal error. It would take 7.31 fluid ounces of my powder to get 7.00 ounces by weight. Given the non-critical nature of the mix, if I didn't use a scale and was forced to use volumetric measures, I would just measure 7 fluid ounces of the powder out (1 cup minus two level tablespoons), and add that to a gallon of water.
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Unclenick - This is EXACTLY what I was looking for.
It’s obvious that you took considerable time and effort to post this information as well as giving sound opinions and advice.
I appreciate the trouble you went through; many thanks…..Frankie
It’s obvious that you took considerable time and effort to post this information as well as giving sound opinions and advice.
I appreciate the trouble you went through; many thanks…..Frankie
passivation
I also read that the pinkish color doesnt hurt the brass either.
The citric acid not only cleans but also passivates the brass; that is it forms a layer of reacted brass (analogous to rust oxidation, but 'passivation' since it occurs in alkaline environments) which actually prevents further corrosion. And that pink layer is the passivated layer.
So you can leave it, but the purists do still wipe it off.
Any chemists know for sure if that pink indicates a passivation layer?
C-
I also read that the pinkish color doesnt hurt the brass either.
The citric acid not only cleans but also passivates the brass; that is it forms a layer of reacted brass (analogous to rust oxidation, but 'passivation' since it occurs in alkaline environments) which actually prevents further corrosion. And that pink layer is the passivated layer.
So you can leave it, but the purists do still wipe it off.
Any chemists know for sure if that pink indicates a passivation layer?
C-
RetiredUSNChief
Member
Why over think this?
Use distilled water for the rinse. Then you don't have to worry about "water deposits", which are really due to impurities in the water and not the water itself.
stubbicatt
Member
Man I'm glad to read this. I had a thread on using ultrasonic cleaner with vinegar, and was told that the tinge of pink meant that it had leached the zinc out of the brass and now it was weak. Here I hear that it is simply passivation layer.
Also I am learning that perhaps the ultrasonic cleaner is not so important, it sounds like a simple soaking in this acid solution will do the trick without the ultrasonic vibes...
Good job UncleNick and others...
Also I am learning that perhaps the ultrasonic cleaner is not so important, it sounds like a simple soaking in this acid solution will do the trick without the ultrasonic vibes...
Good job UncleNick and others...
Unclenick
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I'm pretty sure the pink is copper, but it's copper at the surface where zinc was already attacked by oxidation. Citric acid does not attack the brass itself; only the oxides. The pink appears where oxides are greatest, such as the neck and shoulder where annealing oxidized the brass, and which polishing didn't remove 100%.
Below are before and after photos of my use of the 5% solution in a heated ultrasonic cleaner. The .30-06 cases were LC 72 and were in a plastic bag in a flooded basement. The bag apparently failed to keep the water out entirely.
Unfortunately I didn't have the foresight to mark the cases in a way that would let me line the finished cases up the way they were in the first photo. Still, you can see that all are pinkish where the annealing stain was. A couple are pinkish all over, having been the most heavily oxidized, but others are pink below the shoulder only where the water oxidation was bad.
In any event, an hour in a tumbler with Lyman green media had them all looking like polished yellow brass, so the depth of the pink is no more than the thickness of metal removed by normal polishing and tumbling at the end of each load cycle. Not much.
As to passivation, it is simply leaving metal in a non-reactive state. Sometimes this involves the addition of oxides (chromium oxide in stainless steel, for example) or other surface compounds. Citric acid probably leaves citrates behind, which may help.
In the case of vinegar, I've used the old NRA vinegar and salt mix before and the brass was left activated. Left unpolished, it gradually got purple and green oxide colors and looked badly in need of polishing. If you use citric acid, unless you have oxides that leaves pink behind after reduction by the acid, the brass will just remain yellow. It will darken a little over time, but basically it remains yellow brass colored. This is why citric acid is used by brass part makers as a treatment for brass that's to be left in storage for a long period.
Below are before and after photos of my use of the 5% solution in a heated ultrasonic cleaner. The .30-06 cases were LC 72 and were in a plastic bag in a flooded basement. The bag apparently failed to keep the water out entirely.
Unfortunately I didn't have the foresight to mark the cases in a way that would let me line the finished cases up the way they were in the first photo. Still, you can see that all are pinkish where the annealing stain was. A couple are pinkish all over, having been the most heavily oxidized, but others are pink below the shoulder only where the water oxidation was bad.
In any event, an hour in a tumbler with Lyman green media had them all looking like polished yellow brass, so the depth of the pink is no more than the thickness of metal removed by normal polishing and tumbling at the end of each load cycle. Not much.
As to passivation, it is simply leaving metal in a non-reactive state. Sometimes this involves the addition of oxides (chromium oxide in stainless steel, for example) or other surface compounds. Citric acid probably leaves citrates behind, which may help.
In the case of vinegar, I've used the old NRA vinegar and salt mix before and the brass was left activated. Left unpolished, it gradually got purple and green oxide colors and looked badly in need of polishing. If you use citric acid, unless you have oxides that leaves pink behind after reduction by the acid, the brass will just remain yellow. It will darken a little over time, but basically it remains yellow brass colored. This is why citric acid is used by brass part makers as a treatment for brass that's to be left in storage for a long period.
stubbicatt
Member
Thanks UncleNick. Man you are an encyclopedia of information! I ordered up some of the Midway brand USC solution, I think they call it Frankford Arsenal, and it should be here tomorrow. I shall try the USC again with this stuff and see if I don't get a little bit better results.
Is there a "recommended density" of cases in solution which gets them cleanest fastest? I.e., is it better to only put a few cases in the tub, or to stack them on their case heads, or to lay them on their sides as one would stack cordwood, or...
Thanks in advance.
Crashbox
Member
I have found that about two rounded teaspoons of citric acid per gallon works very well. For a detergent/surfactant I now use Tergitol NP-9 at about a 1:1000 +/- dilution which equates to about four eyedroppersful per gallon.
I run them for about six minutes at approximately 120 degrees Fahrenheit and they do come out nice and shiny-bright.
Citric acid is a must-have IMO.
I run them for about six minutes at approximately 120 degrees Fahrenheit and they do come out nice and shiny-bright.
Citric acid is a must-have IMO.
Unclenick
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An ultrasonic often has a load density limit. I just mainly don't want the cases forced into contact with one another. Also, the more you put in, the more surface area the same transducer is supplying energy for, so the longer it takes to work.
The cases in my image were run in about 120°F water, too (the 48 in the second photo is 48°C or 118.4°F, which is all the heater could get to at the room temperature then in the house). With the ultrasonic running at that temperature it only takes about 15 second for all verdigris to be gone in the 5% solution. However, it took more like half an hour for primer pockets on that old ammo to be 100% clean, so that's how long those cases were in there altogether. The useful thing is, that shows that even with that much time involved at that acid concentration, the brass isn't being attacked.
I was also using a rack with that 2.5 gallon ultrasonic unit that held the cleaning mix and the rinse water in beakers suspended in the bath. The glass in the beakers absorbs a fair amount of ultrasonic energy, transferring it with less-than-perfect efficiency, converting some to heat and loosing some to the plastic rack as heat and some to the air as sound. If I use a stainless perforated rack with the cleaning solution and tune the liquid level to achieve maximum roiling, it cuts the time almost in half. Still, that limits me as to how many cases fit in. I just line them up with bases down and about 20% free space around them. I've also tried this with cases directly on the bottom of the ultrasonic unit, but it didn't seem to like that and performance was lackluster. That may just be how the resonances play out in my unit. It may not be the case with another.
If you want to use a concentrated surfactant, Kodak Photo-Flo is another that a few drops will do for. Back in the day of darkrooms, there were a number of good ones available. At a couple of teaspoons of citric acid per gallon, you would be making a disposable use-once solution.
Still, citric acid is cheap. I buy mine from Duda Diesel, an alternative fuels supply outfit. For $27 they send you 10 lbs, postage paid. That's enough for almost 23 gallons of the 5% mix. They got my order to me in about a week.
Incidentally, citric acid may also be used to passivate stainless steel. If you have something made of stainless that nonetheless picks up rust spots on the surface, that's due to free iron from tooling or other contamination and you can passivate the steel by eating the free iron off the surface. The right concentration for that is usually 10% and you have to degrease first. The best temperature depends on the type of stainless steel you have. The article in the link covers that.
The Wikipedia says that 6% citric acid solution will dissolve water spots off glass. It doesn't say what you do afterward, though I can tell you that rinsing with distilled water is the answer unless you want to use tap water and dry with a dish towel. The choice is just about how old-fashioned you are comfortable with being, I suppose. I can still remember my grandfather drying the dishes with one. Grandma cooked; granddad did the dishes. Surprisingly modern in retrospect, considering they were born circa 1890.
The cases in my image were run in about 120°F water, too (the 48 in the second photo is 48°C or 118.4°F, which is all the heater could get to at the room temperature then in the house). With the ultrasonic running at that temperature it only takes about 15 second for all verdigris to be gone in the 5% solution. However, it took more like half an hour for primer pockets on that old ammo to be 100% clean, so that's how long those cases were in there altogether. The useful thing is, that shows that even with that much time involved at that acid concentration, the brass isn't being attacked.
I was also using a rack with that 2.5 gallon ultrasonic unit that held the cleaning mix and the rinse water in beakers suspended in the bath. The glass in the beakers absorbs a fair amount of ultrasonic energy, transferring it with less-than-perfect efficiency, converting some to heat and loosing some to the plastic rack as heat and some to the air as sound. If I use a stainless perforated rack with the cleaning solution and tune the liquid level to achieve maximum roiling, it cuts the time almost in half. Still, that limits me as to how many cases fit in. I just line them up with bases down and about 20% free space around them. I've also tried this with cases directly on the bottom of the ultrasonic unit, but it didn't seem to like that and performance was lackluster. That may just be how the resonances play out in my unit. It may not be the case with another.
If you want to use a concentrated surfactant, Kodak Photo-Flo is another that a few drops will do for. Back in the day of darkrooms, there were a number of good ones available. At a couple of teaspoons of citric acid per gallon, you would be making a disposable use-once solution.
Still, citric acid is cheap. I buy mine from Duda Diesel, an alternative fuels supply outfit. For $27 they send you 10 lbs, postage paid. That's enough for almost 23 gallons of the 5% mix. They got my order to me in about a week.
Incidentally, citric acid may also be used to passivate stainless steel. If you have something made of stainless that nonetheless picks up rust spots on the surface, that's due to free iron from tooling or other contamination and you can passivate the steel by eating the free iron off the surface. The right concentration for that is usually 10% and you have to degrease first. The best temperature depends on the type of stainless steel you have. The article in the link covers that.
The Wikipedia says that 6% citric acid solution will dissolve water spots off glass. It doesn't say what you do afterward, though I can tell you that rinsing with distilled water is the answer unless you want to use tap water and dry with a dish towel. The choice is just about how old-fashioned you are comfortable with being, I suppose. I can still remember my grandfather drying the dishes with one. Grandma cooked; granddad did the dishes. Surprisingly modern in retrospect, considering they were born circa 1890.
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stubbicatt
Member
Well, I received my Frankford Arsenal USC solution! It is citric acid! LOL. I wonder now whether I hadn't ought to have just gone to the canning section at WallyWorld and bought some there, but this bottle will last me several months I am sure.
Question: Can one reuse the solution, or should it be discarded after one use?
Question: Can one reuse the solution, or should it be discarded after one use?
CountryUgly
Member
LSD it! Much less thinking involved! Real Easy! Here's a Crash Course.... Buy Lemi-Shine dishwasher cleaner (granules in the can DO NOT buy the liquid) ant any Wally World. Pour an empty pistol case (.45acp, .40s&w or any comparable sized case you have handy will work) worth of lemi-shine into 1 gallon ice cream bucket or similar container, a squirt of Dawn dish soap, add nasty brass and fill with HOT water, replace container lid and shake it for a minute of two, set aside for 18hrs or so (overnight) and shake occasionally if you think about it. After it set overnight give it another good shake and empty into a dollar store plastic collander to drain, rise with cold water. Set brass on towel to air dry (you can use a hair dryer of fan to dry faster or even stick in the over for 20 mins at about 190 degrees to dry) When dry toss into corn cob and tumble for the final super shine. It also cleans the primer pockets for you!!
Wow, I must be the lazy one here. I just pour a dollop (cup or two) of cheap lemon juice or white vinegar in with warm water (2 or 3 quarts).
Throw my cases in, three times - shake it up ~ 30 seconds, soak ~15 minutes, pour out the solution.
Twice - fill with clean tap water, shake it up to rinse well.
Throw cases on a table outside in the sun to dry for a few hours.
No measurements just throw plenty of stuff together. Cleans them very well before processing in the press and keeps my dies nice and clean.
Andy
Throw my cases in, three times - shake it up ~ 30 seconds, soak ~15 minutes, pour out the solution.
Twice - fill with clean tap water, shake it up to rinse well.
Throw cases on a table outside in the sun to dry for a few hours.
No measurements just throw plenty of stuff together. Cleans them very well before processing in the press and keeps my dies nice and clean.
Andy
Unclenick
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Lemon juice is easy to obtain, but expensive in the long run. Lemon Juice contains an average of just 1.44 oz of citric acid per gallon. I'm paying about $0.24 for that much, and haven't found a gallon of lemon juice that cheap yet. Around here, buying citric acid as Lemishine or Dishwasher Magic is about 2-3 times more expensive than the citric acid I buy. Lowe's stores as well as some Walmarts have Ball pure citric acid for canning at about $0.57/ounce. You can also buy plain citric acid as Sour Salt from a number of places, but the prices are usually similar to the Ball product or higher. You pay for packaging of small quantities.
Vinegar is another matter. I can buy a gallon of store brand 5% white vinegar for under $2.00. It has about 6.7 ounces per gallon of acetic acid, and citric acid has 3.2 times the molecular weight of acetic acid, which means an equal weight of acetic acid has 3.2 times more acid molecules than citric acid does. Both acid molecules are single proton donors, so that means acetic acid has 3.2 times more potential capacity to eat away oxides than an equal weight of citric acid does. So, figure about 12 fluid ounces of white vinegar (5% acetic acid) has as much oxide consuming potential as a gallon of lemon juice, and 40 fluid ounces (5 cups) has the oxide consuming potential of a gallon of 5% citric acid. (Actual usable capacity is complicated by buffering behavior.)
So, why not flock to vinegar? Same reasons given earlier. I don't like the surface activation. The dark colors that appear make great camouflage for cases ejected into the grass. If I don't use a round for several years after loading it, as occasionally happens, oxide welding of the bullet to the case neck is more likely to start with an activated brass surface. Exterior case oxidation in accidental poor storage conditions would be worsened by an activated surface.
Vinegar is another matter. I can buy a gallon of store brand 5% white vinegar for under $2.00. It has about 6.7 ounces per gallon of acetic acid, and citric acid has 3.2 times the molecular weight of acetic acid, which means an equal weight of acetic acid has 3.2 times more acid molecules than citric acid does. Both acid molecules are single proton donors, so that means acetic acid has 3.2 times more potential capacity to eat away oxides than an equal weight of citric acid does. So, figure about 12 fluid ounces of white vinegar (5% acetic acid) has as much oxide consuming potential as a gallon of lemon juice, and 40 fluid ounces (5 cups) has the oxide consuming potential of a gallon of 5% citric acid. (Actual usable capacity is complicated by buffering behavior.)
So, why not flock to vinegar? Same reasons given earlier. I don't like the surface activation. The dark colors that appear make great camouflage for cases ejected into the grass. If I don't use a round for several years after loading it, as occasionally happens, oxide welding of the bullet to the case neck is more likely to start with an activated brass surface. Exterior case oxidation in accidental poor storage conditions would be worsened by an activated surface.
Elkins45
Member
Another option is the phosphoric acid brass cleaning solution sold by Birchwood Casey. I reused the same gallon for several years before I finally bought a tumbler.
An added advantage of phosphoric acid solution is that it will decontaminate the brass of radioactivity.
On a more serious note, if someone has a hard water problem and doesn't want to purchase distilled water they may use trisodium citrate.
On a more serious note, if someone has a hard water problem and doesn't want to purchase distilled water they may use trisodium citrate.
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