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Color change in the ultrasonic


#1

For years now I’ve been using L&R ammoniated cleaner in a plastic
tub in my ultrasonic. Sometimes pretty concentrated. I use the tub so
it can be sealed and not fumigate the shop.

I pulled a couple of yellow gold rings out and good gosh they were
white. Louped them and it ‘looks’ like a silver coating. Only other
things in the tank were platinum rings and a copper wire, although
previously I may have cleaned some silver articles. I can say there
is not a direct electrical connection between items and the main
tank.

Anyone ever experience this?


#2

Yes, Neil, I have experienced this. Sometimes in the pickle as well.
I’ve chalked it up to dissolved silver in the solution that plates
out through the solution (the electrolyte) onto the work (the
cathode) due to a galvanic effect generated by the differences in the
potential of the hook or another object. Ammonia seems to hasten
this.

I am not, nor do I claim to be a metallurgist, engineer or chemist.
I leave the science of this to Peter Rowe or Jim Binnion. Just my
guess…

Take care, Andy


#3

Hi,

I have experienced something similar, couldn’t understand what was
going on until i found one of the sales assistants putting silver
chains in the ultrasonic straight from a dip in the silver cleaner.

Hope this helps,
Steven


#4
I am not, nor do I claim to be a metallurgist, engineer or
chemist. I leave the science of this to Peter Rowe or Jim Binnion.
Just my guess.... 

I know even less about such things, but out of necessity I made a
hanger for my ultra out of some wire I had laying around… It was
sterling.

I’ve never had that problem since.


#5

Thanks Andy. While its not really a big deal to polish it off, I
could envision while doing a larger batch of things, inadvertently
using white solder on a yellow gold item that had been silverplated
in this way. I guess I will have to add a silver dedicated tub to the
ultrasonic. Funny though I hadn’t experienced this for so many years
and then suddenly it appears. Keeps the game interesting though.

Hmmm…just having a thought…perhaps this phenomena could be used
as a replacement for depletion guilding? Something to try on
tinkering day.