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Old 9th Feb 2021, 6:06 pm   #21
Uncle Bulgaria
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Default Re: Ultrasonic cleaning solution for variable capacitors

Momentary cleaning is fine, but I wouldn't want to leave a vinegar solution in a stainless steel (or any metal) container for long periods of time. My ultrasonic sits there with solution in it all the time, and I fear if that were an acidic one then the steel would be damaged, especially coupled with the periodic heating and ultrasonic agitation.
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Old 10th Feb 2021, 12:13 pm   #22
Trigon.
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Default Re: Ultrasonic cleaning solution for variable capacitors

Apparently even mild acidity can be damaging in combination with other factors...

https://iultrasonic.com/blog/ultraso...dic-solutions/
Quote:
Specifically, aqueous cleaning media with pH values in the acid range (pH <7) should never be used in the ultrasonic cleaner tank if fluoride, chloride or bromide ions will contact the stainless steel either from the cleaning formulation or from removed contaminants. Ultrasonic operation will cause these ions to destroy stainless steel tanks by crevice corrosion in a very short period of time.
...
Potentially damaging chemicals can be released into the bath when removing fluoride, chloride or tetrafluoroborate-containing fluxing agents from soldered metal parts and electronic components; when using citric acid solution to decalcify medical equipment contaminated with physiological salt solution...
Note that washing up liquid typically contains a significant amount of sodium chloride.

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Old 10th Feb 2021, 2:06 pm   #23
Bazz4CQJ
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Default Re: Ultrasonic cleaning solution for variable capacitors

Quote:
Originally Posted by Trigon. View Post
Apparently even mild acidity can be damaging in combination with other factors...

https://iultrasonic.com/blog/ultraso...dic-solutions/
Quote:
Specifically, aqueous cleaning media with pH values in the acid range (pH <7) should never be used in the ultrasonic cleaner tank if fluoride, chloride or bromide ions will contact the stainless steel either from the cleaning formulation or from removed contaminants. Ultrasonic operation will cause these ions to destroy stainless steel tanks by crevice corrosion in a very short period of time.
...
Potentially damaging chemicals can be released into the bath when removing fluoride, chloride or tetrafluoroborate-containing fluxing agents from soldered metal parts and electronic components; when using citric acid solution to decalcify medical equipment contaminated with physiological salt solution...
Note that washing up liquid typically contains a significant amount of sodium chloride.

Cheers
Quite so!!! While I cannot argue if people say that washing up liquid works well, as discussed previously on the Forum at various times, washing up liquid is full of sodium chloride and chloride is the best initiator of corrosion in the world. It is brilliant at starting pitting corrosion in stainless. My professional-quality (Ultrawave) bath is ~25 years old now and has never had chloride anywhere near it, and that day will never dawn!

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Old 10th Feb 2021, 3:06 pm   #24
Trigon.
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Default Re: Ultrasonic cleaning solution for variable capacitors

I wouldn't have thought pitting corrosion would be a significant problem when using washing up liquid, providing the pH remains above 7 ? (i.e. Whatever contamination is being washed off isn't creating an acidic condition.)

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Old 10th Feb 2021, 3:54 pm   #25
Bazz4CQJ
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Default Re: Ultrasonic cleaning solution for variable capacitors

I'd simply prefer not to have chloride in the bath or on the component being cleaned. I note your earlier posts refers to crevice corrosion being caused by chloride. Although the bulk liquid may have a pH>7, what the local pH is inside a pit or a crevice is unknowable.

Of course, we've had references to washing up liquid, vinegar and citric acid and Coke being used so there's scope for all sorts of interactions. I recall the use of "Harpic" being discussed some time ago.

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