LAPIDARY DIGEST
Administered by Hale Sweeny (hale2@mindspring.com)
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This list digest contains the following message subjects:

1. LapDigest Issue No. 120 - Mon 3/2/98
2. RE: How Do I Cut A Cat's-eye Chrysoberyl
3. RE: Lapidary Glues and Cements
4. RE: Lapidary Glues and Cements
5. RE: Dopping Opals
6. RE: Electroforming (Metal Plating) On Lapidary


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<MSG1>

Subject: LapDigest Issue No. 120 - Mon 3/2/98


Are there any topics you would like to see covered more
thoroughly than is usually done in a query-answer format? If
so, please send them to me and I will try to find someone to
write on that topic.

Stay safe; have fun!

hale
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<MSG2>

Subject: RE: How Do I Cut A Cat's-eye Chrysoberyl


Hello Ian,

The simplest and easiest way to orient any chatoyant
phenomena is with a commercial product known as Star
Refractol and a good light source. The Sun is the least
convenient and most superior, I use a 'Maglite' a powerful
focusable flashlight. Chrysoberyl eyes are usually very easy
to find however and can be oriented sometimes with little
more than water or glycerine.

Hang or hold the light as directly above you as possible and
allow the eye produced in a small bead of liquid on the
surface of the gem to guide you to the position of the
required effect, this may take a few goes if the phenomena is
weak, as in most garnet and quartz. Asteriated and
adularescent stones are sometimes cut as eyes too and this is
the easiest way to find that eye. A detailed explanation and
drawings accompany the Star Refractol mentioned above.

A far smaller gem is obtained using the cruder and much much
faster method of grinding to a bead and polishing the eye
and cutting a flat opposite. This method is employed
extensively throughout the Far Eastern cutting houses and is
the reason for the enormous bellies seen on most star
sapphires and rubies.

I have cut Chrysoberyl cats-eye as small as 1.25mm dia. and
have never had a problem orienting them; polishing them
however...I have several tricks to achieving that if you are
interested, none of them involve vertical cutting equipment.

I hope this is useful, this is my first submission to the
group.

Anthony L. Lloyd-Rees
cutter@paralynx.com
web site: http://www.opalsinthebag.com

non-commercial republish permission granted
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<MSG3>

Subject: RE: Lapidary Glues and Cements


In addition to the adhesives discussed here previously, I
want to mention another set of UV cured adhesives made by
Norland Products, Inc., 695 Joyce Kilmer Avenue, New
Brunswick, NJ 08902. They produce two types of adhesives:
for electronic and for optical uses. In total, they make
15 different adhesives. From a careful reading of their
literature, I concluded that the NOA61 adhesive would be a
good one to try on douplet and triplet caps. It was made
for military optics, and has the following characteristics:

Adhesion to glass and metal: Excellent
Adhesion to plastic: Fair
Physical Properties:
Refractive Index 1.56
Modulus (PSI) 150,000
Tensile (PSI) 3,000

The shelf life is short; they date each tube they produce.
They will also give 1/2 oz samples of their adhesives upon
request. One problem I see with their packaging and pricing
is that the package they sell is large, and thus will last a
very long time, at least in my shop!

And it is pricy (but not for the amount you get!) at about
$100/pound, or $6.25/oz. Loctite glass adhesive sells at my
local Home Depot for about $2.50 for .07oz, which is
equivalent to about $35/oz. (YES, THAT IS RIGHT!! The cost of
packaging probably costs much much more than the adhesive!!)
So by comparison, the Norland adhesives are not all that
expensive. They package for the optical manufacturer, who
might use several packages a week.

They will send physical data sheets and MSDS for each of
their adhesives on request.

hale
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<MSG4>

Subject: RE: Lapidary Glues and Cements


There are two excellent manuals on the internet on adhesives;
the first is a manual on structural connections in which the
first type of connection described is using structural
adhesives. This manual, at
<http://www.penton.com/md/bde/rvfj1.html>
describes and defines the various types of adhesives and also
describes which are best for various applications. It is a
basic primer on adhesives.

Next, there is an excellent manual for professional optical
workers entitled "The Bonding of Optical Elements, Techniques
and Troubleshooting" which is given on the web page at:
<www.emsdiasum.com/Summers/optical/cements/manual/manual.htm>.
I think a lot of this will be of interest to us, particularly
to those of us who make doublets or triplets.

Copies of the manual are free and may be obtained by writing
Summers Optical, 321 Morris Road, Fort Washington, PA 19034.
They also have a catalog of their adhesives, but I have not
seen it.

hale
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<MSG5>

Subject: RE: Dopping Opals


I still like to dop with wax. I know I have been told time
and again to use the super glues. I have not had a bad time
with crazing from heat. I just dop opal a little differently
from other stones.

Make sure your dop stick and wax are up to temperature. Put
a few pieces of paper down on the stone warming section of
your dopper. Place the opal on the paper and let it warm
very slowly. After it is hot to the touch, dop the stone and
let it sit until it is cool to the touch. Don't rush this
process. It always seemed it was the fast temperature change
that did in the opal.

Steve Ramsdell
sramsdel@prairienet.org

reprint for non profit use is ok.
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<MSG6>

Subject: RE: Electroforming (Metal Plating) On Lapidary


It has been my experience, and several others I've read and
meet with that when Electroplating with Silver, that you
should also use a vibrator of some sort, such as you use for
casting investment, this helps keep a conductive contact.

Also, be sure not to mix an acid, and a Cyanide Solution. If
you must use the two types of solutions on the same piece,
CLEAN IT THOROUGHLY, a couple of times at least, for your
own personal sake, it generates Hydrogen Cyanide, not good
for the solution, you'll get a drag over which will
contaminate the solution makes it almost impossible to get
a good finish as well as for the piece, again the
contamination makes it almost impossible to get a good
finish.

Gil Shea
legal@mtaonline.net

"non-commercial republish permission granted"
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