Phosphoric Acid to clean cases


Sky King
May 12, 2011, 01:49 PM
Just found a jug of 75% Phosphoric Acid. What mixture would I make to clean cases before I put then in a tumbler? I've used Iosso case cleaner, but that only works for about 1500 cases.

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May 12, 2011, 01:55 PM
Much safer to use straight vinegar.

May 12, 2011, 02:00 PM
75% Phosphoric Acid. Use that to clean the lime out of your toilet bowl.

You don't need to clean cases before tumbling.
Thats what tumbling is for.


May 12, 2011, 02:10 PM
Do a little more research. You can use it. Some of the commercial brass cleaning solutions contain it. Just water it down. Something like a teaspoon per gallon.

May 12, 2011, 03:43 PM
I'll go with rc, the guru emeritus "I think thats what I want to say" here at THR.

May 12, 2011, 04:16 PM
Mr. King,
Let us know how it works out and what mix ratio does the job. Curious what level of cleaning you’ll get in the primer pockets.

Sky King
May 12, 2011, 04:35 PM
Used an old NyQuil measuring cap and used 7.5 ml to 1/2 gal of water with a couple drops of Dawn. Outstanding, after they dry I think a few minutes in the tumbler and they should look better then new. Don't know about the primer pockets, as I left most of the primers in. The ones that I did remove still had a little junk in them, not perfect but good enough. Insides looked good too. Used plenty of water to get Dawn and acid off.

May 12, 2011, 07:48 PM

For that brass that has some of that 'brown death' all over them, bad stains, or really tarnished I use some Limeaway toilet bowl cleaner. The active ingredient in Limeaway is Phosphoric acid. On these rough specimens I just saturate a rag with some Limeaway and wipe down. The bad stuff disappears instantly.. Saves hours of tumble time... Then a quick soak in a vinegar/salt solution and then rinse. Finally a short stay in the oven at 220° to evaporate all the water out.
Phosphoric acid doesn’t harm brass.. At least in a product like Limeaway.

75%..? Hmm.. bet it would kick butt in a shower stall.. Probably don’t need that concentrated of a solution for cleaning brass.

I would like to know.. what kind of tumbler and what media is used to clean cases this bad quickly.. If using another product is unnecessary..
I have a Midway large vibrator tumbler.
I've used the walnut with red rouge and just walnut shell. When using red, all that does is 'hang' on the stains or corrosion and never really 'cleans'. All I get after much time of tumbling is red corrosion instead of brown.

What is the difference between the walnut shell you get at the pet shop and the stuff you get at the gun shop?

May 12, 2011, 08:11 PM
Birchwood case Brass cleaner is a combination of 2 acids plus other "stuff" the % of phosphoric acid is less than 20 % If you source of acid is 75% Then I would guesstimate using 1 cup to water to make a total of 1 gallon.

That is not a true percent mixture but close enough for Govt work.

To start of safe I would use 1/2 cup in a gal of water. Let the brass sit for only 10 minutes or so and then rinse thoroughly 3 times in fresh water.

May 14, 2011, 02:29 PM
I use that stuff to clean RUSTY motorcycle gas tanks.
16 oz. to 5 gallons of water will clean the rustiest fuel tank ever found to white metal. It is NOT intantaneous -or even- overnight.
It takes a good while, but CAN do a perfect job if you are diligent & patient.
If your not careful it will destroy a paint job.
Nuetralize with copious amounts of warm water and final rinse with STEAMING hot water to finish.

I know it's not brass, but I thought you might realize an alternative benefit.

May 14, 2011, 10:50 PM
Just as a suggestion for safety, when mixing strong acids with water, always add the acid to the water, not the other way around.
Doing it the other way can result in a violent chemical reaction, and a face full of acid.

May 16, 2011, 09:29 AM
yep, Acid to Water, Just Like you Otter!

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