I bought a string of maybe 85 or so Chinese turquoise round beads,
from about 17 to 20mm. I really like them, and they seemed like a
pretty good price–because they were not really polished. I had just
bought a small used tumbler, and a set of rock tumbling compounds
from Rio, so I figured a little tumbling with the finest grit would
take care of them. Well, you guessed it. After a couple of hours of
tumbling, they were totally “frosted”. Here I am with egg on my face.
I can hand-polish them quite nicely with tripoli and then zam–and a
lot of time. Is there any short-cut, or do I have to write this off
as another one of those “learning experiences”?
Dear Noel, Most of the Chinese beads are not hard enough to take a
high polish. They are waxed to give that acceptable look of turquoise.
Zam is the only thing which will give that back to you. There must be
some zam compound available for a tumbler which can be used with
walnut or corn cob. Otherwise you have to balance the cost of the
beads (vs) the cost of the new compound, etc., etc, etc. I love those
beads but the look is limited to old looking jewelry. Sam, Tucson
Noel, I don’t know what the best way by tumbler will be, but if you
are reduced to polishing by hand, there is a shortcut. String the
beads on a piece of stiff wire. Attach this wire at each end to
something that will keep it taut, such as a portable vise on one end
and an eye hook at the other. If using a bench polisher, you can just
hold onto the wire at both ends, using shorter lengths of wire and
keeping it taut. Use your buffs and compound against the beads. They
will turn as the buff hits them, thus preventing flatspotting, and
polish them evenly. Rather than stay in one place, drag the buff
across them from one side to the other, polishing them all to the same
degreee. Old Indian trick. Even if you don’t use it for this instance,
keep it in mind. You will come across having to polish some metal
beads sometime, and this is the easiest way, outside of a tumbler.
Noel, Chinese turquoise can be some of the prettiest turquoise in the
world. It is usually harder than the turquoise found in the
Southwest. Polishing beads on a string on a bench polisher can be very
dangerous. Great care must be taken to prevent the string from
warping around the buffing wheel. The wheel can grab the end of
the string and whip it around which can cause serious hurt to fingers
and hands. )nce the end of the string is caught it will pull the
rest of the string out of your hand and become a whip. The best bet
is to make a fixture of a piece of wood with a solid method of
fastening the ends of the string on each end of the wood. Run the
beads parallel to the wheel, not cross to the wheel. This way the
wood will hold the string and the wheel can not wrap the string.
Hope this helps. Lee
Cool trick Katherine described for rapidly polishing beads on a
buffer. Especially great for metal beads. Word of caution… don’t do
this to polish beads that are permanently strung, or you will be
restringing them. The edges on the holes of the beads act as an
abrasive and cut through the string. One of those situations when I
was a little too clever for my own good…
All the best, Dave
Dave Sebaste
Sebaste Studio and
Carolina Artisans’ Gallery
Charlotte, NC (USA) dave@sebaste.com
As to compounds to treat corn cob or walnut, IJS offers 2DL cream, a
paste that is tumbled into the woody media, and is very gentle to the
workpieces. Also, a person could get creative with their powdered
chrome oxide, tin oxide, cerium oxide, or Sapphire/Linde A powder,
plus a dab of mineral oil.
All, I’ve been lurking on this one…seems no one has addressed
some pertinent considerations on this thread.
No. 1 Never tumble polished items that have been drilled. You will
inevitably carry over grit from batch to batch and the results will be
disastrous.
No.2 The softer the material is the more careful one must be about
using the tumbling method of polishing. Turquoise is rarely hard
enough to cost effectively tumble polish unless one uses an extremely
cautious approach. Furthermore, since most of the Turquoise that is
produced here in America is essentially plastic why bother ?
No.3 When I was mining Turquoise in Nevada I developed a method of
polishing Turquoise which was very effective. After doing a clean-up
tumble ,using a small amount of 600 grit carborundum, I would then
thoroughly dry the stones and add them to a tumbler to which had been
added a substantial amount ( approximately half full ) of small, clean
pine shavings and sawdust. To this I would also add about a half cup
or less of Tin oxide. Theoretically, if I were going to do it all over
again, I think I might experiment with Mesquite chips. Mesquite is so
oily that it is very difficult to finish using ordinary methods. Here
in California it is readily available for barbequeing. Ron at Mills Gem,
Los Osos, CA.
All, Thanks for the suggestions, and concern, about my
bead-polishing. Lee, let me reassure you–I unstrung the beads, and
have been repolishing them by hand, one by one, using tripoli and
then zam. They look beautiful, it’s just terribly slow. I like the
group polishing idea (maybe a rigid piece of steel wire would be
best–tougher to catch on the wheel) but I would think that would
leave the “poles” unpolished. Guess I’ll give it a try!
Noel
Noel, I forgot to mention when doing the group polishing on wire, you
should leave some extra space for you to be able to get to the poles
of the beads. A loose buff will insert itself between the beads as
you’re going across the line, thus effectively polishing the
in-between places. Some people have a tendency to be a little more
heavy-handed on the side with their dominant hand. They solve the
problem by flipping over the wire assembly, so what was held in their
right hand, will be held by their left hand. Very stiff ‘wire’ can be
had by getting some cold-rolled round stock in very fine sizes from a
machine shop. This material is very difficult to fashion a ‘loop’ on
each end to hold onto (you don’t insert fingers in the loops, they
just provide more surface area), but a vise with soft grips (or
leather pads) and a pair of vise grips, works well. If there is a
concern with working with a bench polisher, just use your flexshaft.
Don’t press too hard, let the buff and the compound do the work for
you.
Very stiff 'wire' can be had by getting some cold-rolled round
stock in very fine sizes from a machine shop.
Just to amplify Katherine’s suggestion a little, another type of
stiff wire is ‘piano wire’. In the US, many hardware stores sell it
in 3 ft lengths of various diameters. It’s usually $1 or less for a
3ft length.
If it were me, I’d mount the wire to a board so the beads were free
to revolve without touching the board. This can be accomplished by
using a machine screw to raise the wire above the board the necessary
amount.
Here’s how: 1. Obtain 2, 1/4"-20 machine screws 2" long. 2. Obtain 6
nuts for the 1/4"-20 screws. 3. Cut a 3/4" thick board about 2" x
about 4" longer than the strand of beads to be polished. 4. Drill 1/4"
holes through the 2" side of the board about 1" from each end. 5.
Thread 2 nuts all the way on one of the 1/4"-20 machine screws. 6.
Insert the 1/4"-20 screw through one of the holes. 7. Thread a 3rd nut
on the 1/4"-20 screw so the end of the screw is just flush with the
nut. 8. Screw the middle nut down on the board. Tighten it securely.
Leave the top nut loose for now. 9. Repeat steps 5 thru 8 for the 2nd
1/4"-20 machine screw. 10. Form a loop in one end of the wire & place
it around one of the screws, just below the head. 11. Position the
wire so it is in line with the other 1/4"-20 screw. Run the top nut
up to hold the wire in position. 12. Thread the beads onto the wire.
13. Draw the wire taut, wrap it around the 2nd 1/4"-20 screw just
under the head. Form a loop in the wire & twist the end around the
wire. 14. Run the top nut up to hold the wire in position.
Note: Use a wrench or pliers to tighten all the nuts securely.
The length of the machine screws can be changed to suit the size bead
being polished. The wire should be placed high enough off the board
at the ends so that the beads don’t rub on the board when the center
beads are being polished.
For metric screws a M6x1 about 50mm long would be a good size.