Edited and Published by Hale Sweeny
Web Site:
Associate Editors: Geo. Butts, JR Shroeder, Steve Henegar,
Margaret Malm, and Sam Todaro

This list digest contains the following message subjects:

1. LapDigest News for Issue No 269 - Sat 4/1/2000
2. NEW: Tin Oxide Buffing compound
3. NEW: Inexpensive Cabbing Machine
4. NEW: Polishing Jade in Tumbling
5. NEW: Cutting Something Concave
6. RE: Zebra Marble
7. RE: Zebra Marble
8. RE: Spencer Opal
9. RE: Spencer Opal
10. RE: Spencer Opal
11. RE: Heat Treating Carnelian Agate for Color?
12. HELP: Expanding Drums
13. BIO: Michael Workman


Subject: LapDigest News for Issue No 269 - Sat 4/1/2000

I want to introduce Sam Todaro, who's a new Associate Editor
for the Digest, specializing in interaction of lapidary and
health and safety. Sam has been, as he says, a cutter,
sculptor and jewelry designer for years. He is also a CSP
(Certified Safety Professional); his MS degree thesis dealt
with arts and crafts safety. I'm happy to have him with us.

I was ready to send the Digest last Monday, and then I LOST
over half the messages, and still don't know how I could
have deleted them!!! But I did. If you sent one to the
Digest in the past week, and you don't see it here, please
resend it! There was one message I remembered as it
fascinated me. I have poorly reconstructed it and it is
appearing below as a contest! Will the person who sent that
query about an inexpensive cabbing machine please write me?

The proposed Mentoring program will be started shortly. We
are still working out details. I do know that we are going
to start with a very few Mentors and add when we find that
we need more.

Noel Rowe sent in a very complete description for making
Spencer opal triplets (below). He also noted his new e-mail
address is and his new phone number for
both fax and voice is (408.292.9716).

I have been tacking on some suggestions which came from a
document named: "rules to live by". The rule for this week

"In disagreements with loved ones, deal only with the
current situation. Don't bring up the past."

Good advice. Solve today's problems and leave yesterday's
problems out of it! They just muddy up the waters.

Have a fun weekend!


Subject: NEW: Tin Oxide Buffing compound

I like using tin oxide in buffing opal. I have been carving
some boulder opal and don't like the mess the water based
paste makes when buffing the various contours. I am using a
small buffing cone with mandrel at the end of the flexible
shaft on a Dremel-type tool.

I would like to know if anyone has a recipe for making a
buffing compound that is similar to the bar style used
with a standard buffing wheel on a basic bench grinder.
I want to make a tin oxide bar and don't know what works
best as a binder to hold the tin oxide in a solid form
(most likely a wax). If anyone has knowledge of the
binding material(s) and mix proportions, please respond.

Thank you.


Subject: NEW: Inexpensive Cabbing Machine

One of the messages which was lost expressed a great need
for an inexpensive cabbing machine - one in the $100-$200
range; that is all he could afford.

Aside from finding a great bargain on eBay or elsewhere,
the only thing I could think of was to put one together
from component parts, as many scrounged as possible. The
cheapest one might be using an arbor, motor, SiC wheel
maybe of 100 grit, expanding drum, SiC belts, and a
polishing pad disk on the end. But I am sure there are a
lot of other configurations.

OK, guys, put on your thinking caps and dig out those
catalogs and design the least expensive cabbing machine you
can. You don't have to meet the $200 maximum, but the cost
will be a big, big factor. Specify the parts you would use
and why you would use them, and specify where you would buy
them - also specify the
catalog used, their costs and the total cost. If you know
of any way to get parts cheaply - for example, a used motor
from some household appliance - spell it out and spell out
how you would modify it for the cabbing machine. Send your
plan and list of materials and costs to me at; the best ones will be published and
the winner will receive a prize - yet to be selected - but
I guarantee any lapidary will like it!

If you want to send in a sketch of the proposed design,
send it to me at 3500 Cambridge Drive, Durham, NC 27707


Subject: NEW: Polishing Jade in Tumbling

Do you have any information on the tumble polishing of Jade?
I have polished some small nodules of Jade, but I'm not able
to bring up the final polish.

Is there some recommended polishing medium or procedure?


Subject: NEW: Cutting Something Concave

Hale -

I have a very old wrist watch with a broken crystal. I can
cut a piece of glass or quartz that would be the right
length and width, and can cut the dome for the outside, but
have no idea how to form the inside of the dome. I have
tried to have the watch repaired, but local repair people
cannot get a crystal that will fit the watch.

Can anyone help me?????

Tom Wilkie
Kingsport, Tenn
Hi Tom: Let's see what the members say, but I just opened
my top bureau drawer and found two lenses from an old pair
of glasses which seemed as if they could be cut down to make
a watch crystal... The inside is already cut and polished
and you can trim down the thickness after you cut it to fit
the watch. hale

Subject: RE: Zebra Marble

First, I am not sure the Utah Zebra Rock is the same thing
as the Zebra Marble someone was asking about on rockhound
a while back. However, A zebra rock does indeed occur in
Utah, north of Milford a ways. You can buy it at the Rock
shop in Milford -- I think they are the owners of the mine.
Their name is Bradshaw. Address: 101 N. Main St. Phone:
(405) 387-5554. They also carry (and are the mine owners
for) Picasso Marble.

Margaret Malm

Subject: RE: Zebra Marble

If you know of another source for zebra marble let me know.
We plan on going to Utah this year if we could collect that
would be great. If not I will just have to buy it. It would
be nice to be able to pick out material.

Thank You for any information that you can give. I
appreciate it so much.

Terry Garber

Subject: RE: Spencer Opal

Have you been to the Eclectic Lapidary e-zine website? In
the April '97 issue (in their archives) there's an article
called "Kitchen Table Triplets" that describes an approach
to making them. The author uses wet/dry sandpaper(!) on a
flat plate to flatten the stones. This is the sandpaper
they sell in auto parts stores, or hardware stores. Silicon
carbide. And cheap.

You should be able to go to:

Then go to archives, then pick the issue. I don't think
you have to register, but it's free. And besides which,
Carol is good folk like Hale and good to support.

Hope this helps,
Thanks, Bob - Carol is that. She's a peach and Han's article
on kitchen table doublets would be right on for him. hale

Subject: RE: Spencer Opal

About Spencer Opal: Triplets are the main product of Spencer
opals. Some of the material is thick enough to make doublets
and occasionally (rarely) you can make a single cab.

The saw to use is something like a Faceting type with a thin
blade (I use a 5" blade that is .004" thick in a Rock Rascal
saw). Then I hold the piece of Opal by hand and cut between
the color bands, hopefully parallel to the color band. Then
I use a 6" All-U-Need to cut down to the color. When that is
done I glue a black backing stone to that side. Then I do
the same thing to the other side, except I put a Quartz Cap
on that side. Use a good non-yellowing glue (I recommend 330
Epoxy, which dries water clear).and be careful not to get
bubbles between the stone and the cap!!!!

The saw can be any saw! Preferably it just needs to be a
small saw so you can put on a thin blade and do manual
trimming (a Facetors Saw?). It just depends on how close the
color bands are in the stone that you are cutting, cause if
you cut a 1/16" or larger kerf you loose that much distance
between color bands (some color bands will be close enough
that you will cut them off with a thicker blade). Some
people have used Genies (or similar) for polishing the
color bands. I was never able to get the band flat enough
with a round grinder. Usually a Flat Lap is too big for the
size of stones that are available! That's why I have been
using a "All-U-Need".

Hope this helps !! LOL and if you need more info, just send
me an e-mail!
Just an added piece of advice about sawing. Hold the opal
with the first two fingers of each hand, pressing on each
side of the opal with your first and second fingers, and
possibly add the thumbs lightly on top of the opal. Then
facing the edge of the blade, lower the opal toward the
table top, but support it away from the table top with
your third and fourth fingers, which are bend under. That
way, the opal does not touch the table top, and you have
excellent control of it during sawing. hale

Subject: RE: Spencer Opal

Jed said: <<I recently purchased, at a bargain basement
price, almost 40 pounds of Spencer Opal rough and would
like to start making triplets. <snip> > I’m on a very
strict budget so funds are limited.>>

Hi Jed,

Wow, 40lbs. with color, that should keep you busy for a
while ;-)

I've been cutting Spencer opal as well as opal from other
locations for some time now. I still like silicon carbide
for the final work as it's less aggressive than diamond.
The key to triplets is proper orientation of the fire band
(especially with Spencer opal where the band is sometimes
thinner then a piece of paper) The brightest fire band must
be located and oriented absolutely parallel to the backing

To identify and isolate the brightest fire band it's best
to work in direct sunlight. If direct sunlight is not
available, the next best light source is a 100 watt clear
incandescent light. I find it helpful to sand any jagged
edges off the rough to make it easier to see the fire all
the way around. Keep the stone wet until the fire band is
located. Turn the stone so that you are holding the fire
band horizontal & rotate it to make sure it runs completely
through the stone. If there are multiple fire bands identify
the brightest one. After you have done this take a fine tip
indelible felt marker and carefully trace on the fire band
completely around the stone.

Dop the rough opal to a round wood dowel, large enough to
provide a strong support for the stone. Mount the dop in
the vice of the trim saw so that the marked line is parallel
to the saw blade. (Set the vice so that the cut will be
about 4 or 5mm beyond the marker line.) Make the cut.

Remove the opal from the dop. Lap on a flat lap with 180
mesh diamond lap or 100 grit silicon carbide disk to remove
the bulk of the potch. Be sure to check your progress often.
It is very important to stay parallel to the fire band. As
you cut if you notice one side is thicker than the other
you can control the cutting by applying more pressure to
the thicker side. Once the fire just begins to show switch
to the 220 mesh diamond lap or 400 grit silicon carbide and
cut approximately one third of the way into the fire band.

After you have lapped down to the fire band clean the stone
with alcohol and inspect it for any fractures. If you find
a fracture you have the option of treating the stone with
fracture sealer or cutting the stone to eliminate the
fracture. (The quartz will not have any fractures although
it will magnify any obvious blemishes in the opal below).
If you choose to seal a fracture use a good two-part sealer
such as Opticon. Apply a coat of the sealer without the
hardener and put the stone in the oven at 150 degrees for
15 minutes. Remove the stone from the oven and wipe clean
with a soft lint free cloth.

To prepare the backing, cut a slab of Basenite approximately
1/8" thick, large enough to extend beyond the opal 1/16" on
all sides. Lap both sides flat on the 180 diamond lap (100
grit sc.) followed by the 400 mesh lap. Wipe the slab clean
with alcohol and set aside to dry. Place the Basenite slab
on a piece of waxed paper about the size of a note card. In
a plastic bottle cap or on a piece of doubled aluminum foil
squeeze out a dab about the size of a kidney bean of both
the epoxy and the hardener. Use a slow setting, crystal
clear epoxy such as Epoxy-330. Carefully mix the epoxy
slowly trying to avoid adding air bubbles. Allow the epoxy
to sit for about two minutes, using a Popsicle stick
transfer enough epoxy to the Basenite slab to cover the
area, which will hold the opal. Don't spread the epoxy,
instead allow it to flow from the Popsicle stick onto the
middle of the slab. Carefully take a tooth pick and gently
push any air bubbles in the epoxy to the edge of the flow.
You don't need a great deal of epoxy, just enough too
lightly float the opal when it's placed on the slab. Gently
place the opal on the slab and allow it to sink into the
epoxy. Gently push the opal down onto the slab, squeezing
out some of the excess epoxy. Set the assembly on a level
surface and allow to cure for a minimum of 24 hours.

Go to the expandable drum, on the 100 grit belt, and sand
back the edges of the Basenite until the edge of the opal
is reached. Lap on the 180 mesh (100 grit SiC) until the fire
from the band closest to the backing starts to show. Be sure
to check often to make sure you are staying truly parallel
to the backing. Adjust the pressure as required to stay
level. After the fire starts to show through switch to the
400 mesh diamond lap (or 400 grit SiC) and continue to lap
the face of the opal until it has thinned to the thickness
of about two pieces of paper. Wipe the start clean with
alcohol and allow to dry. At this point you have two
options. You can either use a commercial quartz top on your
triplet or you can cut your own. If you opt to use a
commercial top clean the surface of the opal with alcohol
and allow to dry. If the opal shows any fractures apply a
coat of Opticon and follow the same procedure as above.
Select a commercial cap, which will fit as close as
possible the size of the start. Next prepare another batch
of epoxy using the same procedure as for gluing the opal to
the backing. Follow the same procedure for gluing as before:
gently place the quartz cap directly on top of the epoxy.
Allow it to settle naturally, then gently push down on the
cap to force out any remaining air bubbles (remember an air
bubble will show up as an unwanted light reflection in your
finished stone). Once you are satisfied all the air bubbles
are out set the stone on a piece of wax paper on a level
surface to dry for another 24 hours.

If you decided to make your own quartz top the approach will
be somewhat different. If you want to cut a calibrated size
stone now is the time to define the size. Mark it on the top
of the opal start with a water proof fine tipped marker or
aluminum pencil. On the cab unit sand the start to the
marker line. Select a piece of optical grade quartz large
enough to overhang the start by 1/8 inch all the way around.
Wipe the opal with alcohol to remove any marks and set
aside. If large enough, saw the quartz to approximately ¼"
thick. Lap to remove any saw marks. Lap both sides. finish
on the 400-mesh lap. The reason you want to lap both sides
is so that you will be better able to see any bubbles which
might be trapped in the epoxy before it sets up. Mix the
epoxy as above and proceed as detailed above for commercial

After the epoxy has cured for 24 hours you can dop the stone
as you would any other opal & cut like any other cab with
one slight difference. The girdle should be slightly beveled
so the quartz cap slightly overhangs the backing (otherwise
you'll get a black ring around your stone)

One final alternative, which I have had a chance too try
myself, is a relatively new adhesive, which depends on the
UV rays from sunshine to cure. The product is called
"Crystal Clear Glass Adhesive" and is made by Duo, a
division of Manic Corporation, It comes in .07 fl.
Syringes, It's a thin, bubble-free adhesive, allows you to
move it around before it set up, and is water clear. It's
been talked about here on the digest before. I found it at
ACE hardware. It cures exceptionally fast. I haven't been
using it for very long so don't know how it will hold up
ten years from now (I know the epoxy will).

I hope this helps,


Subject: RE: Heat Treating Carnelian Agate for Color?

Hi Dan:

According to Gemstones and Chemicals, this is the process
that I have used:

Pour a layer of clean builders sand in bottom of pan, to a
depth of about 1 inch.

Add a layer of slabs or cabs,

Cover with about 1/2 inch of sand; you can add alternate
layers as long as top layer is sand and at least 1
inch deep.

In a normal Kitchen oven, the following heating Schedule
is recommended:

175 F Several Hours (Overnight is fine)
275 F Four Hours
375 F Four Hours
475 - 500 Four hours

Allow the Pan and contents to cool in the Oven Overnight
or Longer or at least until the pan feels only warm.
If you open prematurely Fracturing is Likely to result.

Good Luck


Subject: HELP: Expanding Drums

We are working on a project which has to do with the fit
between expanding drums and belts, and we very much need
your help.

If you have an expanding drum NOW (one you don't have to
take off the machine to install the belt), please write me
and tell me:

1) the size and width of the drum,
2) the maker of the drum (usually on the side of the drum),
3) the approximate age of the drum (new/old), and
4) whether you have ever had trouble with the fit between
belt and drum.

Thanks. This input will be of value to all of us.



Subject: BIO: Michael Workman

Hi Hale,

I have been reading the digest for awhile and enjoy it very
much. So I am ready to put my 2 cents in the pot and see
what happens.

I am a full time cabochon cutter, up to 10 hours a day, 6 to
7 days a week. Sell about $50,000 in cabs per year. I
believe that is somewhere below minimum wage but as a rock
hound I am not complaining. Mainly cutting freeform cabs,
some call them designer cut. Sell on eBay and my web site

I am a Marine Corps Viet Nam vet 1965-66. Live on the
central coast of California. Was a building contractor,
suction dredged for gold in the Sierras, hard rock mined for
Gold, Silver, Platinum, and gem stones in central California.
Owned a rock shop retail outlet for a couple of years. I am
55 years old. Now I own "The Little Shop of Treasures", and
work out of a home office. There is a "Who am I" section on
my web site that goes into a little more detail, if
interested. I just brag a little more there.

Although I can and do hand cut up to 150 cabochons in a day,
including Australian Opals, there is one thing I have
learned in lapidary. No matter how much, how long or how
well I do in lapidary there is always a lot left to learn
and new materials to cut. Lapidary never becomes dull.
Therefore I wish to offer what knowledge I have in your
mentor program. I am sure I will also take advantage of the
other members knowledge. I am always looking for new
materials to cut.

Thank you and keep up the good work,

Miner Mike
Michael Workman
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