Ultrasonic cleaning of Brass- corrosion of stainless?

A friend is cleaning brass prior to reloading in an ultrasonic cleaner using an old formula-
1 qt H20 1 cup vinegar
1 Tsp salt 1 Tsp soap
Seems like a couple of the pans have corroded through on different brands of unit- destroying the ultrasonic cleaner. The brass should not be in contact with the pan (there's a stainless basket, or plastic in the 3rd one he's trying).
Any reason why this would happen? There's not that much difference between (presumably 400-series) stainless and brass on the electrochemical series.
Thanks for any leads..
--
Best regards,
Spehro Pefhany
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On 05/26/2015 06:33 AM, Spehro Pefhany wrote:

If the brass is touching the bottom of the tank, the tank will erode. The brass is acting like a 20 KHZ jackhammer.
I used to build ultrasonic cleaners, the 1 KW+ type. They do have a tendency to self destruct.
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Gary A. Gorgen | "From ideas to PRODUCTS"
snipped-for-privacy@comcast.net | Tunxis Design Inc.
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The vinegar salt mixture is essentially poor man's hydrochloric acid. It is chewing the heck out of the stainless. It is probably also corroding the brass.
In any case, definitely get rid of the chlorine. Try citric acid or sodium bisulfate. But my real suggestion is to separate your brightening and cleaning operations. Use the acid to remove corrosion without the ultrasonic machine. Then clean in the ultrasonic with a mildly basic cleaner to neutralize any acid residue.
Paul K. Dickman
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I put about an inch of water in the ultrasonic tank. Anything to be cleaned goes into a glass beaker with a solvent. Place the beaker in the water in the ultrasonic machine. The only fluid that touches the ultrasonic tank is water. Clean up one beaker and the job is done. I don't have any large objects that need ultrasonic cleaning.
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I have a recently made "stainless steel" kettle that pitted through from heating tap water. I filled the hole with TIG and now the HAZ around it is rusty.
-jsw
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On Tue, 26 May 2015 12:44:24 -0400, "Jim Wilkins"

I've got an old commercial espresso machine and sometimes I take a housing off (400-series stainless) and run it through the dishwasher- the bulk of the stainless comes out gleaming but the spot welds are developing rust. Something to do with (lack of) passivation..
--
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Spehro Pefhany
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Get some cheap plastic bowls that will just fit in the cleaner tank, put the brass and cleaning solution in the bowl, put the bowl in the tank, and fill the tank with water to the full mark. Run for a month or two until you decide the inside of that bowl is getting rough, toss it, and repeat. I save 1-3 lb margarine tubs, coolwhip tubs, whatever (and have asked friends to give me theirs on occasion), both to use as cereal bowls and to use in my ultrasonic cleaner. Yes, you lose just a smidge of cleaning power but the stainless steel tank will now last "forever" :-).
----- Regards, Carl Ijames carl.ijames aat deletethis verizon dott net
"Spehro Pefhany" wrote in message
A friend is cleaning brass prior to reloading in an ultrasonic cleaner using an old formula-
1 qt H20 1 cup vinegar 1 Tsp salt 1 Tsp soap
Seems like a couple of the pans have corroded through on different brands of unit- destroying the ultrasonic cleaner. The brass should not be in contact with the pan (there's a stainless basket, or plastic in the 3rd one he's trying).
Any reason why this would happen? There's not that much difference between (presumably 400-series) stainless and brass on the electrochemical series.
Thanks for any leads..
--
Best regards,
Spehro Pefhany
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On Tue, 26 May 2015 09:33:56 -0400, Spehro Pefhany

Perhaps the fired gunpowder/primer residue creates a more exotic solution? But salt and vinegar in water are potent.
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