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Polishing cabs- low tech


#1

Hi folks, I picked up some cananea turquoise chunks recently and
trying to polish it is giving me something of a headache. Apparently
the bits are not even in density and when I try polishing, I am
getting some undercutting in the softer streaks. I don’t have a well
equipped shop (just a flex shaft and old grinder) so any low-tech
solutions to getting a more even surface would be greatly welcomed.
Thanks!

Dawn in central Texas


#2

Dawn,

Turquoise can be cut and polished in a very low tech way by hand.
You can use simple sanding sticks with different grades of emery
cloth.

Polishing can be done with a piece of leather charged with Cerium
Oxide. Of coarse this is a very slow process. My suggestion would be
to experiment with different cutting and polishing wheels in your
flexshaft as well as polishing compounds until you find what works
best for the stones you have.

Good Luck
Greg DeMark
Longmont, Colorado
email: greg@demarkjewelry.com
Website: www.demarkjewelry.com
Custom Jewelry - Handmade Jewelry - Antique Jewelry


#3

Dawn,

Greg is correct about hand cutting turquoise with various grades of
sanding paper…but we are talking silicon carbide right!

Polishing is a different matter. Cerium Oxide was an old staple for
polishing turquoise but these days it is much easier to polish it
with ZAM, which is also an excellent metal polish. ZAM on cotton
muslin buffs will bring turquoise to a very high polish. It also
does miracles on malachite, rhodocrosite and other phosphates and
carbonates.

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut2


#4

Dawn,

There are several abrasive wheels that can be mounted in your
Foredom which can be used to cut and shape stones with the hardness
of turquoise.

There are aluminum oxide cut-off discs that range in size from 7/8"
to 1 1/2" in diameter. They can be mounted on a mandrel in your
foredom handpiece.

There are silicone cut-off discs that range in size from 7/8" to 1"

There are diamond sanding discs that mount on the end of a mandrel.
These have the advantage in that the mandrel screw does not
interfere with sanding.

Check out the catalog of jewelry tool suppliers

The size of stone you can cut and shape into a cab is limited in
the size of disc you use. You can easily cut and shape stones up to
an inch in diameter with the larger cut-off discs.

The process is time consuming and creates a lot of dust unless you
cut under a water drip system. I made a lot of inlay jewelry using
cut-off discs and my Foredom until I bought a rock polisher.

Contact me off line if I can be of specific help in describing the
process. I could send photos of the process.

Lee Epperson


#5

Hi Dawn,

Sometimes when I deal with material that undercuts, I like to use
diamond compound paste with cup brushes in my flex shaft after
shaping grinding and sanding the stone. You can get it in grits down
to 100,000 from several places. Because they are local to me, I get
mine from Graves. You can order from them on-line at
www.gravescompany.com and they are supplied in syringes that are
labeled. Individual grits are available, as well as “kits” of more
than one grit. They also sell diamond powder in various grits if you
want to try making your own compounds, or charge faceting laps. For
your application, I’d recommend the compounds.

Cup brushes are just as they sound, little brushes with bristles
that point downward in an inverted cup shape. There are at least two
types: white bristles are harder, black bristles are softer. Start
with harder bristles and a heavier grit, working down to softer
bristles with a smaller grit. Faster than sandpaper, but still not
as fast as a cabbing machine. And that’s really the point. I’ve
always had better luck polishing materials that undercut by slowing
down the process. Good luck, and let me know how you fare.

James in SoFl


#6

Hi folks,

Thanks for the replies so far! I don’t know what they’re made of
but nail sanding sticks seem to work great - I got a nice smooth
flat surfaces on my turquoise pyramid. Not quite done with it, but
it is looking good.

I have a question about Zam - I started out using green rouge
because that is what my Grandma used, but I heard/read so many folks
rave about Zam that I got some. I like the silky smooth finish it
gives, but is the stuff supposed to be so dry? Also, I’ve found
that if I give a final buff with a chamois or nail buffer the stones
look even better.

Also, thanks Don for the tips on stones. I knew malachite was soft
enough to work with, but didn’t realize rhodocrosite (etc) was also.
Cool.

I love trying new things!
Dawn in Central Texas