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

This list digest contains the following message subjects:

1. LapDigest News for Issue No 252 - Tues 12/7/1999
2. NEW: A Fifty-Pound Truck-Tire Rock Tumbler
3. NEW: Another Way to Apply Water to Diamond Wheels
4. NEW: Diamond Saw Blades
5. NEW: Making Large Flat Surfaces
6. NEW: Whale Wax?
7. NEW: News from Agate Creek, Australia
8. RE: Expanding Wheel, Belt Too Tight
9. RE: Does Sandstone Crack Opals?
10. RE: Does Sandstone Crack Opals?
11. RE: Does Sandstone Crack Opals?
12. RE: Doublets and Triplets
13. RE: How to Apply Cerium Oxide to Leather
14. RE: How to Apply Cerium Oxide to Leather
15. RE: Suiseki - Is It a Form of Lapidary?


Subject: LapDigest News for Issue No 252 - Tues 12/7/1999

Regis Galbach wrote: "I'd like to thank everyone for the
tips on charging a leather belt (with cerium oxide). I
found out there are a few ways that work and I can actually
use more than one method." It feels good to get that kind of
letter. It means the Digest is doing what we wanted it to

Did you remember that this is the date on which the Japanese
Navy attacked Pearl Harbor? This is another of those dates
which most people who were alive then can tell you exactly
where they were when they heard the news! We have had too
many days like that; it just has to STOP! Let's have peace
for a while!

Take care, guys.


Subject: NEW: A Fifty-Pound Truck-Tire Rock Tumbler

Alan Silverstein, who produced the large file on tumbling
which is in the Archives, has designed and built a large
tumbler based on a truck tire as a barrel. He has also
documented the calculations for the design, the construction
and construction problems, and operating experiences with
this large tumbler. You may read about it in a document:
"A Fifty-Pound Truck-Tire Rock Tumbler: Specifications and
Experiences", which may be downloaded from:

Site 1: <>

The document is 17 pages long, 131 kb long and in Acrobat
(.pdf) format; you will need an Acrobat reader to read
it. The reader may be downloaded (free) from many sites,
such as:

Site 2: <>

Site 1 is the website of Lennart Widmark. You might look at
the rest of this site; it includes a picture of the tire
tumbler he built.

I found both sites and the document well worth seeing and



Subject: NEW: Another Way to Apply Water to Diamond Wheels

In keeping with the tradition of this list, I would like to
share a "trick of the trade" that I learned recently from
an experienced lapidary. This may be one of those situations
where this is not a new trick, but one that this old dog is
just now learning. But, it works so well that I am going to
pass it on so some of the other digest members can try it

I use 6 of the Diamond Pacific Nova wheels on my arbor, but
I do not own one of the expensive Titan machines. Since my
arbor does not have one of the water spritzers that you
place under the wheels to lubricate them with water, I have
been experimenting with various water feed systems. My goal
was to come up with a lubrication system that was the
simplest and with the least amount of overspray, since I
have my arbor inside my garage. I tried suspending a bucket
of water higher than the machine and feeding water through
tubing to the water inlet ports on the arbor (a hole is
provided above each wheel), and this worked all right, but I
always seemed to have more water lubrication than I needed.
With the water dripping right down on the wheels, there
always seemed to be a lot of overspray coming off the top of
the wheel and out the front of the arbor.

I also tried a couple of different types of under-the-wheel
spritzers and they worked too, but still with a lot of
overspray coming off the wheels.

Then one day, I was participating in a gem and mineral show
out in Oregon, and the vendor who was set up next to me was
polishing some beads using a Diamond Pacific Pixie machine.
I wandered over to see what he was working on and discovered
that he had a great idea for lubricating the diamond wheels
that I had never seen before.

He had bought some very large and thick square sponges (like
you would use to wash a car) and he had wedged them
underneath each wheel. The sponges were thick enough so
that the bottom of the wheels rubbed against the top of the
sponge, depressing the sponge about a quarter of an inch. He
poured in just enough water so that the sponges drew up
enough water to keep the wheels wet. This lubricated the
wheels sufficiently and evenly, and the amount of overspray
coming off the top of the wheels was just about nothing. He
had placed a block of wood behind each sponge to make sure
the wheels did not push the sponges too far against the back
wall of the arbor, and to make sure the wheels stayed in
contact with the sponges.

I couldn't believe how simple this idea was! It eliminated
the need for any external water source, electric pumps or
tubing of any kind. You simply pour in a little water from
time to time, and you can adjust how much lubrication you
want just by raising the water level a little. It was such
a great idea I just had to try it. I bought the sponges and
set everything up, and it works beautifully! I put one under
my hard diamond wheel as well as the Novas, and I was amazed
at how little overspray there was. At the end of the
polishing session, I just remove the plug and drain the
water out of the pan.

So, for those of you who would like to keep a bit drier
while you work on the diamond wheels, or eliminate an
exterior water system, give this a try. I think you will be
pleased with the results.

Vance McCollum
Earth Relics Co.

"Ready-to-wear pendants of the finest agates & jaspers"

Subject: NEW: Diamond Saw Blades

Hello Hale and members,

I don't recall ever seeing a complete answer to this query
and wonder if any knowledgeable list member could describe
the specific differences between the types of diamond saw
blades: continuous rim; notched rim; sintered, etc.

Perhaps even a description of how each is manufactured and
if each is repairable and characteristics of each type of
blade. Sure would be helpful to me and perhaps others also.


Gail Clark

Subject: NEW: Making Large Flat Surfaces

Hi all,

Our club shop is looking to buy a new (or used) machine to
grind and polish flat surfaces on the order of 8x10 inches.
Since the shop is only open for 4 hours at a time, I'd like
a machine that works reasonably fast, so a project could be
finished in a session or two.

I've seen the vibratory lap machines that use grit and water
and the rotating diamond disk machines. My initial thoughts
are that vib laps are too slow and diamond disks would
become too expensive when scaled up to do 8x10 inch pieces.

So I'm looking for another alternative. Any ideas?

Brad Smith
Los Angeles


Subject: NEW: Whale Wax?

I just bought a bunch of used lapidary equipment. In the
box that contained polishing compounds like cerium oxide,
red rouge, and tin oxide there was a small bag that had a
block of what I initially thought was paraffin. The faded
Grieger's label identified it as Whale Wax.

Does anyone know what it's lapidary uses were, and did it
really come from whales??


Chunk Kiesling

Subject: NEW: News from Agate Creek, Australia

(In one of his Notes from Lightning Ridge, James Dumas
talked about Agate Creek. Frank is another list member and
sent this added information about Agate Creek)

Hello Hale:

Sorry but I could not let the comments pass about Agate
Creek. I own the only agate claim in there. No more will
ever be released. This area is now designated a restricted
area for rockhounds. I don't know if James has ever been
there. It sounds like he has not. I have been there about
20 times over about 18 years, and have done a lot of very
hard work. Some of the holes I dug were down to 17 feet
deep. Like all holes, some were no good. That's a lot of
work for nothing. I have found some very good agate, and
some terrible rubbish. Sometimes I dug for a week or more
and did not have a good agate to show for my work.

Then you have the good days. My best day, I dug about 60
kilos of good agate. Of that I would think that 4 or 5 were
good enough for my collection of agate. On an average day
I might dig 15 to 30 kilos of reasonable to good agate.
That involves about 6 to 8 hrs of solid work. The biggest
agate I ever found was about 100 kilos. I still have not
had it cut.

The days of getting truck loads of agate easy or otherwise
is long gone, probably 30 years or more ago. There is only
small amounts of agate coming out and it has been that way
for a very long time. We love to have people coming over
here to visit and dig for agate and other gems, but we
like them to have the correct information too.

If you do come to Agate Creek you will find agate but you
will work for it. Some times after rain or a flood in the
creek, you can spec some nice agate. There are areas where
you can pick up small broken agate in quantity for tumbling
TONS AND TONS OF AGATE. I do have a small quantity of agate

Hale, here is a photo of my favourite agate that I dug about
15 years ago.



Subject: RE: Expanding Wheel, Belt Too Tight

Jan Berg (Berg's Rock Shop) sent me a note off-list pointing
out that "3x8 inch" belts come in two lengths- 25-1/8" and
25-7/32". Depending on what I'm working, I pick from an
arsenal of some 21 belt grades including a 3x8 leather
polishing belt. On the two wheels, I zigzag through the
necessary grits from shaping through 100k diamond. All of
these belts have a catalog "spec." of 25-7/32". Exact
lengths are hard to measure but they all "fit" the wheels
about the same- ranging (on my two good wheels) from where
I can just slip a 1/8 inch rod under the belt to a few where
an inserted pencil is snug but doesn't compress the wheel.
On the "bad" wheel, every belt is *#%#@! to fight on/off.

In the catalogs, the wheels are all a generic, "3x8 inch
expanding wheel". An 8" diameter would mean 25-1/8" as its
circumference, easy to measure by marking an overlapping
newspaper band. My two good Raytech wheels are 25" even and
24-29/32". My "bad" Scott-Murray Lortone wheel is 25-1/4".
On that wheel, I have to squidge the rubber a bit to work a
belt into place and, in place, it's a real tight fit.

I note my Lortone measured circumference is 1/8" longer than
an 8" wheel would be, 1/32" longer than the 25-7/32" catalog
specified belt length and 8/32" to 11/32" longer than my
Raytech wheels.

Thus, the "good" wheel diameters are undersized by 1/16" and
1/32". The "bad" wheel is oversized by 1/16. This isn't
much to raise a fuss with a supplier about. Yet, this 1/8"
diameter means about 3/8" in length, significant indeed!

So, you might buy a wheel from a dealer who allows returns,
measure and send it back if it's too tight. On the other
hand, I'm not keen about paying $4 to $6 return freight for
every trial purchase.

The idea of honing the spinning belt down with a file
appealed to me... until I thought about the safety factor.
There are big time warnings not to run the wheel without a
belt. I have no experience with exploding rubber drums to
refute hazard here but, I'm just too chicken to think about
attacking the running wheel while it's in a state of
unrestrained expansion (ref #251-8).

I DO have the problem of belts "walking" on startup.
Rather, than stopping and restarting, I cut two wood blocks
to 3" width with a bit of taper and tacked a 1" wide strip
of nylon plastic to each side. I start the machine with
this "tool" placed in front of the wheel, the strips of
nylon on each side of the wheel acting as start-up guides.
As soon as the centrifugal force grabs the belt, I take the
guides away. At our lapidary club, there is only one wheel
involved and the folks just use a wooden dop stick to nudge
or hold the belt in place for the first few revolutions...
(ref #251-9)

...George Butts (

Subject: RE: Does Sandstone Crack Opals?

<<He said that he believed that leaving sandstone on the
back of an opal would cause it to crack.>>

Opal is formed by very small balls of silicon dioxide
(quartz); think of a box of Ping-Pong balls. If the balls
are all mixed up you get opal without fire. if the balls
get to form plane surfaces you get fire from a diffraction

Cracks actually form at a molecular level due to a
concentration of stress on a single bond between two
molecules (or atoms). Spheres in opal tend to act as 'super
molecules' so cracks form between instead of thru the

Polishing is a 'butter' effect (unlike grinding, which is a
scratching effect) that produces a(n optically) smooth
surface. Interruptions of the surface produce stress,
eventually leading to cracks.

The best opals come with polished backs.

Potch (sandstone) on the back of an opal breaks the surface
and leads to molecular stress and eventual cracks.

I thought this was common knowledge.

Kreigh Tomaszewski
Please visit our family web pages at

Subject: RE: Does Sandstone Crack Opals?

On first principles it's certainly not implausible. You
have two somewhat different materials intimately bonded,
one of them, the opal, being notoriously brittle. Reason
suggests there will be a small difference in coefficient of
thermal expansion between the two materials; this will set
up stresses which, if large enough to cause fracture at all
will fracture the weaker material.

So much for reasoning. But I've never heard it said that
leaving matrix fractures opal. If it did, that would play
hell with matrix opals. Curiously, what I have heard is
that if you grind too much matrix away that's when the opal
begins to fracture, which runs directly counter to the
logic of my first paragraph.

Hans Durstling
Moncton, Canada
Freelance writing. Feature stories, technical ad copy,
clear manuals, bid documents, simple english, videos,

Subject: RE: Does Sandstone Crack Opals?

Regarding sand cracking opals:

I speak from personal observation, not as an authority. It
seems of the opals I buy, many turn up at home to have
cracks on the front (non-sandstone) side which, as far as I
can tell, is caused by purchasing them.

The hand removal of opal from its seam might involve
chiseling with the blows presumable more likely near the
backside than the face. Perhaps that would induce stress
fractures more on that side (although many might be through
and through fractures) If that were the case, the fracture
predates subsequent sandstone wetting, etc. One would have
to look at a lot of opal and critically count fractures on
both sides to determine if there is likely to be a

Mintabie and other thin seam opal exposed to blasting and
bulldozing would need to be considered in a different

Just an opinion.

David Hemry

Subject: RE: Doublets and Triplets

Hi Folks,

I did a how-to story about two years ago for Carol Bova's
"Eclectic Lapidary" on how to make doublets and triplets on
the kitchen table. As far as I know that story is still up
in the archives of the Eclectic Lapidary Magazine at

As a quick postscript I just finished up 13 doublets
tonight, polished 'em with 14,000 diamond on a hard felt
wheel. The result is a devastatingly brilliant polish
better than anything I've ever been able to get with
cerium oxide. The downside is the felt builds up heat
quickly so now have only 12 doublets.

Hans Durstling
Moncton, Canada
Freelance writing. Feature stories, technical ad copy,
clear manuals, bid documents, simple english, videos,

Subject: RE: How to Apply Cerium Oxide to Leather

I'm amazed at how much trouble people take with this. It
seems pretty simple to me.

I have Richardson's leather buffing disk. I use a spray
bottle of water to get the disk wet and keep it wet as
necessary. You can tell by how "sticky" the wheel feels
when you press a stone to it.

To apply cerium, I get the stone wet, dip it into a plastic
tub of cerium (kept covered when not in use) to pick up
some cerium, and gently touch it to the wet, spinning disk
to transfer the powder. Then proceed to polish.

Yes, some powder comes off, and some cerium-bearing slurry
drips off. This material mostly collects on the surface
below the vertically mounted disk. It's easy to pick it up
with a clean finger and reapply it to the wheel while it's
spinning. I lay a rectangle of jeans material over this
surface when I'm not using the wheel, to keep it

Alan Silverstein

Subject: RE: How to Apply Cerium Oxide to Leather

For anyone wanting to try the "Ivory Soap and Oxide" method,
let me correct what I wrote before you do. I was relying on
my memory and that was a mistake.

The original formula came from Ken Fitzgerald of Fitzcorp,
Inc.; he was using aluminum oxide but any oxide should work.
His research into polishing action would indicate that the
improvement attributed to a pH change when using vinegar
was, in fact, due to the change in surface tension. The
same or better result could be attained by other compounds,
such as some soaps and alcoholics, that did a better job of
reducing surface tension. Of the soaps he worked with, Ivory
Bar Soap worked the best.

The corrected formula is, one 4 oz. bar of Ivory Soap, cut
into shavings, one pound of oxide, and two cups of water.
Heat slowly until it reaches a thick cream texture.

This makes a lot of polish, I would at least cut it in half.

Rub the cream onto the polishing surface, before turning it
on. Then when more polish is needed just dip the cab into
the cream.

Keep the cream in an airtight container; if it dries out
the result is a rubber like glob that won't do much of
anything. I have tried to add water back into it and have
never been successful.

I have used it, and it works, but I have not been able to
convince myself that the result is much better than oxide
and water. It may be a more convenient way of applying for
some people.

Dick Friesen

Subject: RE: Suiseki - Is It a Form of Lapidary?

A while back, we had a great thread on Suiseki. Here are a
couple of very good links; they are being listed using the
same thread name we used before, so they will be included
in the Archives in the Suiseki thread:

Thanks to Rob Dunster for sending these to Rockhounds list;
I did not copy his message, only the links.


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