Cleaning brass in Ultrasonic cleaner

[ColinR]

Rox Absolutely, the water is filthy black after the cleaning cycle. If the water did not go black when you used yours something was definitely not working properly and given the size of your tank I would expect you to clean 150 .308 cases with ease. Mine with 100 cases slows down and the pulsing is quite subdued butstill cleans in 20 minutes.

[ColinR]

Good point Phaedra1106 I will try moderating the heat. Never though of using Bicarbonate of soda - I have a 25kg bag, so now found a use for it!

[rox]

Rox Absolutely, the water is filthy black after the cleaning cycle. If the water did not go black when you used yours something was definitely not working properly and given the size of your tank I would expect you to clean 150 .308 cases with ease. Mine with 100 cases slows down and the pulsing is quite subdued butstill cleans in 20 minutes.

Oh it did go black.

PS - the bicarb process is exactly the 'neutralising' process I was talking about - trying to offset the effect of an acid of unkown strength using an alkali of unknown strength. In my opinion, and that of the chemist I spoke to, an exercise in futility that is likely to do more harm than good (although maybe it could remove the surface copper that remains after the zinc has been removed!). During my years working in metal finishing I don't remember any chemical cleaning process that was removed with anything other than water.

..

[physeptone]

I think you are using too much citric. I used to use 1/8th teaspoon (using food measuring spoon of that size) in 250ml water, but noticed the discolouration you discuss.
I have now dropped that down to 1/16th teaspoon in 250ml.

I use this to clean 10x 45-70 or 20x 44 mag cases- citric with a drop (literally) of detergent in 250ml water. Sonicate for 25mins. After this time add 1/2 teaspoon of bicarbonate of soda and sonicate for further 5mins - lots of gas bubbles in solution as acid/base react to produce CO2, these bubbles in solution should help the cleaning process from what i understand about the sonication process.
Cases then sonicated in water for a rinse cycle (5 or 10mins depending on how i feel) before drying on kitchen towel then low heat ~60deg C in oven for 20-30mins.

Larger quantities of citric don't help cleaning i would say.

[ColinR]

I think you are using too much citric. I used to use 1/8th teaspoon (using food measuring spoon of that size) in 250ml water, but noticed the discolouration you discuss.
I have now dropped that down to 1/16th teaspoon in 250ml.

I use this to clean 10x 45-70 or 20x 44 mag cases- citric with a drop (literally) of detergent in 250ml water. Sonicate for 25mins. After this time add 1/2 teaspoon of bicarbonate of soda and sonicate for further 5mins - lots of gas bubbles in solution as acid/base react to produce CO2, these bubbles in solution should help the cleaning process from what i understand about the sonication process.
Cases then sonicated in water for a rinse cycle (5 or 10mins depending on how i feel) before drying on kitchen towel then low heat ~60deg C in oven for 20-30mins.

Larger quantities of citric don't help cleaning i would say.

I think I may well be using too much citric acid, but what I can say is that it certainly does contribute to the cleaning as the brass goes bright almost immediately which has nothing to do with the ultrasound action - a bit like putting a penny in Coca Cola.Good idea putting detergent in the solution as this will certainly aid wetting, but not so sure about the bicarb given the advice in an earlier post here and the unknown (?) reaction with the brass given the bubbling you report. I will try 1 tablespoon of citric acid crystals to 2 litre and reduce the water temperature and see what, if any, difference it makes to the 'coppering' problem and efficiency of cleaning and report back.