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This list digest contains the following message subjects:

1. LapDigest News for Issue No. 57 - Sat 9/6/97
2. NEW: Sodium Silicate for Cat's Eye Materials
3. NEW: Reynolds Metals Polishing Powders
4. RE: Chrysoprase
5. RE: Trim Saw Lubricant
6. Re: Trim Saw Lubricant
7. NEW: Flat Vibratory Lapping
8. Re: Vibratory Lapping


Subject: LapDigest News for Issue No. 57 - Sat 9/6/97

The Index has been updated through Issue 56, and is in the
Archives, as IndexTo56.txt. The instruction to get this
index is written on the subject line as
get indexto56.txt
and sent to

If any of you have ideas on a better way to organize this
index, please let me know. All suggestions welcomed!

Looking over the new index, I was surprised by the small
number of queries which go unanswered. And looking at the
unanswered ones, I am also surprised that some of them pass
by with no comments. For example, Mark Liccini noted (see
Digest 50) in a post copied from Orchid mail list that you
could make your own diamond paste. No one picked up on
this and commented. Also Andy Parker (in Issue 49) asked
several questions about saws and sawing which were
completely skipped over.

Hope you enjoy this issue!


Subject: NEW: Sodium Silicate for Cat's Eye Materials

I just recalled another use for sodium slicate (water
glass) in lapidary work. In addition to cold-dopping for
slabbing or heat-sensitive cabs, it helps in cutting some
cat's-eye materials like tourmaline. The parallel fiber
bundles that create the "eye" effect are sometimes hollow.
This can be a big problem when polishing agent is forced
into the tubes, leaving a very unsightly cab. If this
happens to you, an ultrasonic MAY get the powder out, but
it's better to avoid the problem.

When the dopped cab is pre-polished, soak it in water glass
for a couple of hours to fill the tubes. Wipe it off with
a paper towel and let it dry overnight. Sand again lightly
with your final sanding grit to remove the surface water
glass, then polish as usual. Soak the cab again in water
to dissolve the w.g. I'd recommend doing this even if
you're polishing with diamond compounds to avoid the
contamination from grit being carried from one pad to
another in the tubes.

Rick Martin

non-commercial republish permission granted

Subject: NEW: Reynolds Metals Polishing Powders

hale asked:
<<Anyone care to comment on the new polishing powders
available from Reynolds Metals? They apparently have
controlled particle sizes.>>

I have been using them for about a year and am very happy
with them. They come in .2, .35, .8, and 1.5 micron sizes
and are available in 4oz, 1lb, and 5lb packages.
Distributed by Diamond Pacific.

If you want a real treat, polish a piece of obsidian with
cerium oxide, then polish again with the Reynolds .2 micron
powder. I usually have trouble finding the surface with a
ten power loop.

Dick Friesen

Subject: RE: Chrysoprase

Been meaning to jump in before now, but the query in Issue
52 on Chrysoprase hit me hard. It is my favorite of the
silicas. I did extensive research into this subject for a
couple of friends in the chrysoprase business, and consider
myself somewhat of an expert. I started to get detailed, but
I will keep it simple for now, having wiped-out a paragraph.

Poland was the original source for the Russian Czars until
the beginnings of the 1800's. That source dried up and
chrysoprase was discovered by the gold rush people around
the Porterville, CA area, in the later 1800's. Tons were
shipped to Russia and a small amount to Germany. This source
went to greener pastures when the Czars were overthrown in
the early 1900's.

I have been to all of the major deposit areas in California,
and forget the Australian. This rock has been found
in (most) any area that has nickel. That is the stuff that
"stains" the silica just the same as copper stains the silica
for Gem Chrysocholla. This list of such areas includes Oregon,
Brazil, Australia, Africa, and future spots not yet found.
It hides very well, with Australia and Brazil being the
only significant spots of major concern for the present.

This stuff is worse than turquoise in the sense that very
little of it is gem grade. Most of the very best never is
seen outside of the Hong Kong cutting district. We do not
get the best grades of rough material anymore, period. If one
can find some of the big pieces of gem rough from the
Marlborough district (Australia) that was mined in the 1960's
and 70's, buy it! Now and then it turns up in an old
collection. Otherwise, the orientals control all of the new
material coming from 'Oz. And rightfully so, they bailed out
the miners in Australia and have first crack at what leaves
the land of 'Oz (that's Australia, by the way).

Value of the highest is based on several factors. Size of
stone is paramount...a 40x30 is a Giant stone, and the
carat price soars as the stone grows in size. Color follows
behind as there are several grades to consider. The Oriental
prizes the dark transparent green to blue green stone with
no yellow cast. The lighter transparent green is mostly what
is seen in the States, and as such is generally what is most
popular here. Next comes the yellow greens and the
translucent to opaque types. There is an odd one that is
starting to catch on though, and that is the near white ones
that exhibit an adularescence and/or aventurescence. These
stones Glow!

There is also something that is starting to be utilized, and
that is the bunk grades that most of us see at rock shows.
This is the rock that has the veils and spots of magnesite
(white) and magnetite (black) and a soup of other spots and
inclusions in it. Many outstanding cabs can be cut from some
of this better "C-grade" material. And, good carving material
can be found as long as the carving can be done that takes
advantage of the various flaws (especially those damn
pits!!!) of this rock.

As to what is the best mail order? This is a gamble, because
of what you may be expecting is not what your seller can
offer. It is not so much as a "buyer beware" (though that
should always be understood) situation as much as it is a
buy a little and cut. Then decide. Better yet, see it in
person and look at what is being cut from it. Look closely!
And remember, the best grades do not come to the U.S. in the
rough in great quantities. A 16x12 A-grade stone is a pretty
good size to expect from fairly good material, and should
sell for several dollars a carat. As the size goes up beyond
this, the price per carat goes up and up and up.

Hope this is helpful.

Brewster McShaad
Riverside, CA

<You can quote me freely and contact me for further

Subject: RE: Trim Saw Lubricant

I use RV coolant in my trim saws up to 10". NOT THE AUTO
ANTIFREEZE!!! It has alcohol that is absorbed directly through
the skin,and is TOXIC!! The PINK stuff does not. Again, do not
use the yellowish auto coolant, use the pink RV coolant.

Everything washes up with water when you do. Saws run at
slower speeds and with blades larger than 10" will run well
in diesel fuel. It has a fairly low flash point and does not
usually ignite. However,there are exceptions to everything,
and I would recommend saws always be monitored when cutting.


"non-commercial republish permission granted"
(Ed. note: The material Frank refers to is Dowfrost RV from
Dow Chemical Company. He said, in personal correspondence,
"All I've ever seen has been pink, guess it could come in
other colors. States right on the label that it is odorless,
tasteless,and contains no alcohol. Want to get technical??
It has a "propylene glycol base" ! I use it full strength
because it cost about $3.50-$4.00 per gallon (even less on
sale) and my trim saws don't hold that much." Thanks, Frank.

Subject: Re: Trim Saw Lubricant

I tried several saw oils years ago and either the smell or
the reaction to the skin curled me...I nearly decided to buy
preforms only. Then, through research in old magazines I
came across a reference to Shell Oil Co.'s Pella A.

It is hard to find and available in 55 gal. drums and
sometimes in 5 Gal. pails. Finally I found a product that I
could live with. I have used this oil in all of my saws--24"
down to 4". As it was explained to me by a rep. at an oil
wholesaler, the Pella A is one extract away from "baker's
lubricant" (used to lubricate the paddles in large commercial
dough making machines). It is colorless and odorless, cuts
cool and clean (nearly as good as motor oil & kerosene
mixture) and has a high flash point.It mists very little,
does not react to the skin, and basically resembles water,
except that it does not rust metal. Also, it cleans from the
stone with an overnight journey into the UNsented, cheap,
generic "cat litter". I've never used it on porous rock, but
would not recommend is oil.

For stones like turquoise, I use water and throw out after use.

Footnote for a rock that stopped cutting: the last time it
happened to me, I took it out of the vise and made a couple
of cuts with an old 220 grit silicon wheel. The blade
worked wonders after that! And after a hundred cuts or so
(18" saw), when it "sounded" like it was laboring, I
sharpened the blade again...your saw will talk to you if you
listen to it long enough.

Brewster McShaad
Riverside, CA
You can use this info freely.
(Ed. Note: There are several good oils designed specifically
for use in rock saws; Brewster uses Pella A by Shell Oil.
Another is AlMag by Texaco, and still another is Finecut by
Contempo Lapidary.

The lubricating division of Shell Oil has an e-mail address
for technical questions, but I can't find it now (Damn!) Will
publish it when I find it. Shell Canada's address is

Texico's e-mail address is <> and their 800
number is <800-782-7852 Option 4>


Subject: Flat Vibratory Lapping

I have a Star Diamond flat lap, 12", that I picked up at a
yard sale. I've tried using it a few times with only marginal
success. The slab, or thunder egg, or whatever - just wants
to stay in one area of the pan. I've tried adding weight,
doing one stone, doing several, the results are all pretty
much the same. I have a separate pan with a piece of
carpeting for polish. Same problem. Is it a levelling
problem? Is the pan worn out? How level does the machine
have to be? HELP!!!
al macneil

Subject: Re: Vibratory Lapping

On weighting thin slabs; the instructions that came with my
Raytech vibratory lap recommend 1/4 lb. per Square Inch on
slabs less than 1" thick. It also recommends steel or lead
slugs attached with dopping wax.

I recommend lead. It is heavier and it won't rust. You can
probably get all you need free at your local tire store. They
just throw away all those lead balance weights that they take
off when tires are re-balanced.

On joining tubing; I use a hair dryer to heat it up. If you
lay it on the edge of a table, you'll have both hands free to
work the dowel into the tube.

Gary Ogg
Columbia, SC

* Non-commercial republish permission granted *
Ed. note: Had never thought about remelting tire weights,
but after reading that, I called my tire store, and was told
that they usually sell them to a recycler, but they would
give me 20 pounds or so. ... hale)
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