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