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Makeing silver rock hard for durability


#1

Hi, everyone! I have developed a line of wire wrapped jewelry with
pearls and stones mixed in. My dilemma is the final polishing and
the upkeep of the silver. I bought a vibratory tumbler for that but
I noticed on a necklace that the carnelian stones were "pitted"
after tumbling. Is it due to the type of tumbler or shape of the
shot? I use a mixed shape steel shot with dishwasher soap (an
Orchid tip). Any suggestion?

Thanks to all in advance.
Vera B.


#2
 carnelian stones were "pitted" after tumbling -- 

I think the pitting comes from tumbling in media that is harder than
the stone. I never tumble finish with stones in place. You might
want to try a different media, but basically, it’s not a good idea to
tumble something with a finished stone in it. I guess diamond and
corundum would probably resist the steel shot, but I’d still be
hesitant.

Bill


#3

Vera, Streel shot is much harder than carnelain and will damage it.
For cleaning and polishing those types of pieces, whether gold or
silver or whatever, use crushed walnut shell in a vibratory or rotary
tumbler. You can add a few scrapings of rouge as well. I have been
using the same batch of wlanut shell and rouge for over twelve
years!!! Takes a litle whle but nodamage… You should be able to
get crushed walnut shell (or corn cob) at most lapidary suppliers or
at any gunshop, where it used to reclean and polish
bbrass ammo cartridges. Wayne


#4
     Hi, everyone! I have developed a line of wire wrapped jewelry
with pearls and stones mixed in.  My dilemma is the final polishing
and the upkeep of the silver.  I bought a vibratory tumbler for
that but I noticed on a necklace that the carnelian stones were
"pitted" after tumbling.  Is it due to the type of tumbler or shape
of the shot?  I use a mixed shape steel shot with dishwasher soap
(an Orchid tip).  

Vera - There are few if any stones that tolerate tumbling in steel.
I have seen successful tumbling of glass set in silver - although
some orange peel texture occurred on flat surfaces.

You might try using walnut shell or wood chip media charged with a
bit of chrome oxide or Simichrome (the car chrome polish). The
carnelian should be ok, but I’d run a small trial with a few pearls

  • I wonder if they wouldn’t pick up some of the color (green) from
    the chrome oxide.

Using dish soap is not as good as the prepared liquid sold for use
with steel shot. You need not only cleaning, but surfacants and
something to make it all slippery.

Judy Hoch


#5
 it's not a good idea to tumble something with a finished stone in
it.  I guess diamond and corundum would probably resist the steel
shot, but I'd still be hesitant. 

In general, I’d agree with Bill. I have, after careful
consideration, successfully tumbled jewelry with garnets and
amethysts in stainless steel shot. Stainless steel shot is softer
than carbon steel shot. Stainless shot is softer than most
quartz-based stones, and anything higher on the Mohs scale. Hardness
of the stone isn’t the only consideration, though… other
characteristics like cleavage and inclusions must also be
considered. Bear in mind that steel shot (stainless or carbon) has a
burnishing effect, which is different than abrasive media.

Blaine Lewis (New Approach School for Jewelers) teaches using a
stainless steel burnisher, made from a modified fork tine, to flush
set colored stones. He has established a correlation between Rockwell
hardness for metals to the Mohs hardness scale for stones. I believe
this is covered in the tools section of the second video
in his video set. <Subliminal message: “Get the videos… go to the
school… get the videos… go to the school…”> :wink:

On the subject of carnelian, I was surprised to see it listed as a
no-no for the ultrasonic on the lists that were shared last week. In
my mind, it is chalcedony, and chalcedony is generally quite durable.
In doing a bit of research, I read one comment that states most
commercially cut carnelian is dyed chalcedony. I guess that would
explain why one might have trouble with the ultrasonic? I’m making a
pin now with carnelian… I’ll have to be more careful with it than I
thought!

All the best,
Dave
Dave Sebaste
Sebaste Studio and
Carolina Artisans’ Gallery
Charlotte, NC (USA)
dave@sebaste.com


#6

The “dimple” effect you notice on carnelian is liable to be from the
stones chipping - due to impact - rather than wearing away from the
steel shot. It’s those same impacts that make the silver work
hardened.

Tony Konrath


#7

Carnelain is indeed a quite soft stone. In medieval(and earlier)
times, the stone was used to make signet rings and wax seals, because
it was so easy to carve and did not stick to hot wax. The advice
about walnut shells and a vibratory polisher are your best bet. I
use a prepared polishing paste w/ my shells(smells like shoe
polish…probably is for all I know), and get very good results out
of it w/ soft materials. Pewter can be so soft that a regular paper
towel will scratch it, but walnut shells do a good job doing a
prepolish on it.

David Cowling


#8

Hi, all,To Dave, about Carnelian: the reason that an ultrasonic’s no
friend of Carnelian’s is that the latter almost always begins as a
heat-treated Chalcedony (like the Brazilian Uberaba Agate), which
contains iron oxide. Upon heating, two things happen: first, the
iron disseminates itself throughout the tiny voids between the
cryptocrystalline quartz crystals that make up the Chalcedony –
much the same as titanium dioxide and iron filter throughout the
crystalline matrices of certain Sapphires, when heated – and,
second, as it the stuff cools, those voids that’re now dyed with the
iron cool at slightly different rates than those without, and minute
cracks form. End result: Carnelian is Chalcedony, but a slightly
less durable form of it. (At least, at the molecular level… to
anyone who’s actually had to cut the stuff, it’s still plenty hard,
and tough!)

Hope I’ve helped demystify things a bit.
All the best,
Doug