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Ultrasonic cleaner problems


Hello folks, Sorry if this is a foolish question but its the second
time I have run into this problem. Marks being produced in the
ultrasonic cleaner on my silver jewelry. The first time I used a
larger, stainless steel type which cost about $300. but it didn’t
have one of those little plastic baskets to put the jewelry on in the
cleaner. So I thought that I maybe had left it in the machine
touching the bottom too long and so got that strange fuzzy cloudy
mark in the center of the flat brooch. I was using some one else’s so
haven’t had one to use in several years. Then last month I saw a
cheap plastic Chinese version for cleaning home jewelry for $50. and
thought it might do until I save up enough for a better one. Well
after finishing a piece which had to be delivered to the Embassy for
Canada Day I put it into the cleaner for only about 10 minutes, if
that, watching it all the time and lifting the basket out fairly
often to check if the rouge was cleaned off and even before it was
off I saw that fuzzy mark on the middle of the highly polished brooch
back!! Needless to say it was panic city as I had to re-polish and
now I want to throw the thing out the window. So can anyone explain
exactly what the machine does and what rules there are for use and is
it worth using at all. Should I just bite the money bullet and get a
better one or what!! I am beginning to think its an over rated
machine for jewelers.

Thanks for all your help now and in the past. P.S. The mabe pearl
advice of sanding the domed back and adding a wire inside the bazel
was perfect and it set like a dream! Forgot who told me so thanks to
whom ever.

Sharron in Saigon having just taken photos of the banana tree fruit
bud which burst into flower yesterday.


Sharron: RE your problem with brooch.

  1. did the brooch touch the tank ? contact however slight can cause
    the item to be cleaned to become scratched

  2. how dirty was the solution? dirty solutions could act like an
    abrasive and “cloud” the highly polished piece.

  3. did you attempt to “preclean” with soap and water before the
    ultrasonic? this would reduce the time in the ultrasonic

  4. 10 minutes in an ultrasonic is generally more than enough time
    to clean most designs.

Mike & Dale
Lone Star Technical Services
The ultrasonic repair guys. “If you don’t need us today we’ll be here


Hi Sharron, I’ve seen these same marks-- whitish, whispy, cloudlike–
on sterling left in the ultrasonic. I’ve attributed them to some sort
of imperfection in the surface of the metal. Ultrasonics can be
brutal machines and will find pits, firescales and uneven areas in the
metal that you never picked up on with your naked eye. I believe also
that once a small imperfection is exposed the cavitating action of the
breaking bubbles-- which scrub the item being cleaned-- continue to
work hard on that area, leaving a wider and wider mark.

I’ve noticed this most often on cast pieces-- which are inherently
less dense and often porous-- and definitely accelerates in the
presence of ammoniated solutions.

Andy Cooperman

 So can anyone explain exactly what the machine does and what rules
there are for use and is it worth using at all. 


Ultrasonics work by driving very high frequency sound waves through
the solution. What that does, is to create many microscopic pockets
in the liquid of near vacuum for a moment, which become a tiny gas
bubble, expanding and collapsing in time with the vibrations. These
are too small to see, for the most part, and form most often at any
"weakness" in the liquid, which usually means some point of focus for
the sound waves. Surfaces, particles of dirt, suspended particles in
the solution, all act this way. These “cavitation” bubbles are
expanding and contracting at very high speeds, about the speed of
sound within that liquid. And though they are not actually bits of
abrasive, the effect can sometimes be aggressive enough, and abrasive
enough, simply through this very high speed motion of the liquid
around those bubbles, that an ultrasonic cleaner can litter ally
damage softer surfaces. The classic test to see if your ultrasonic is
working well is to suspend a piece of aluminum foil in the tank.
Often it takes just a few seconds for the energy of the vibrations to
punch myriad little holes in the foil. Turns it quite literally into
a sieve, sometimes. And that’s quite what it is supposed to do.

with gold jewelry and similar harder metals, and harder gems, this
action is not generally capable of damaging a surface. But Aluminum
is soft enough that the liquid can punch holes in a foil, or start to
etch anywhere there is a pit, casting pit, flaw, etc, in the surface
of a thicker item. Silver, either sterling or fine silver, is
similar. It depends much on the hardness of the piece, and the nature
of the metal. Annealed, cast sterling silver is soft, with a coarser
crystal structure, and almost certainly, a bit of porosity, whether on
a scale you can see or not. The pores concentrate the ultrasonic
energy, and you get particularly high amounts of surface abrasion
there. As a general rule, if you have new and clean solution in a
good ultrasonic, and you put a cast sterling item in there, it will
start to degrade the surface rather quickly. A dirty solution will
not do it as quickly, since the suspended dirt in the solution
dissipates much of the ultrasonic energy. And if you’ve got properly
rolled or forged metal, or you age hardened the silver, then the
ability of the ultrasonic to harm it will also be much less. Items
which have been burnished/tumbled in steel shot will also be less
likely to be damaged, since the burnishing tightens up surface pores
and hardens the surface.

Don’t toss your ultrasonic. Just be aware that for sterling silver,
it’s not the best machine. for your gold, and for most gems, it’s
safe and effective. There ARE some gems that should not go in there
either. turquoise, malachite, some pearls (especially mabe’s), and
other such soft gems (apatite, maybe even peridot, for example) can
sometimes be damaged by an ultrasonic cleaner. Stones under
considerable stress or strain, or those especially fragile for some
reason, should also not go in there. Tanzanite should almost never
go in an ultrasonic, as it’s often under considerable internal strain.
And any oiled or fracture filled stones, such as most emeralds, and
some rubies, will also risk having their filling removed, which makes
them then look terrible. So they shouldn’t go in. Lots of folks will
tell you as well, not to put opals in an ultrasonic, though i’m not
sure I agree. If an opal has no existing fractures, I’ve never had a
problem with them. but I guess I’d not put a larger or more valuable
one in the tank… Obviously, costume jewelry set with foil back
rhinestones will quickly be destroyed, as the ultrasonic removes the
foil backing from the stones at the same time as it unglues them…
And so it goes. Use common sense, recognizing that this machine does
in fact use a rather aggressive and powerful cleaning action, even if
you cannot see it. It’s a very useful cleaning tool. It’s just not
for everything.

Peter Rowe


Hello Sharron,

I have used Ultrasonic cleaners with silver jewelry for many years.

  1. You don’t want any highly polished flat surface to rest on the
    bottom of the basket. Hang the piece from a plastic coated wire hook
    that has minimal contact with the piece. You can buy or make a wire
    rack to hang several pieces.

  2. The number of pieces that you are cleaning affects the
    performance. Don’t put try and clean too many pieces at a time.

  3. Agitation will speed up the cleaning time. If you are using a
    basket, slowly raise and lower it in the ultrasonic. Most of the
    polishing compound will come of in the first minute.

  4. Almost any detergent will work in an ultrasonic. I have been using
    dish detergent for years.

  5. Hot cleaning solution works better than cold. A heated Ultrasonic
    is best.

  6. You get what you pay for. The better units have more power and last
    longer. I have not seen a plastic unit that is a true ultrasonic
    cleaner. They just have a buzzer attached to the bottom of the tank,
    not an Ultrasonic transducer.

  7. Don’t let sludge build up on the bottom of the tank. This will
    absorb power and can even wear a hole in the bottom of the tank.

I will put my vote in for Crest Ultrasonic Cleaners. I have been using
one for 7 years with no problems. I have opened it up out of
curiosity. It is a well made unit with industrial stack transducers,
not the flat piezoelectric ones. It is a better made unit than others
that I have repaired.

I’m not a representative of Crest. I’m just surprised that I have not
seen them mentioned on the list before.

Timothy A. Hansen

TAH Handcrafted Jewelry
P.M.B. 131, 305 N. Second Ave.
Upland, California 91786-6028

E-Mail: @Timothy_A_Hansen


Tim: Agreed, Crest makes a good unit. ELMA (German company) also
uses industrial stack transducer assemblies on all their units. Lone
Star is a factory authorized repair facility for ELMA units both
commercial and industrial/scientific. Just an additional note, The
unit manufactured by Dental Resources of Delano, Minnesota is a true
ultrasonic cleaner. You see them on e-bay a lot for about
$78.00(plus/minus) Actually a pretty decent little machine, can’t
compare to ELMA or L&R or Crest and others but for "quickie cleaning"
pretty darn effective. My wife has one.

Best Regards

Mike & Dale
Lone Star Technical Services
The ultrasonic repair guys. “If you don’t need us today we’ll be here tomorrow”