Stabilizing Turquoise and Opal
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I've noticed the term "stabilized" used with respect to turquoise and
certain opals, and I assume this is a process of curing flaws in a stone
so as to be able to shape and polish it without getting a lot of cracks
...What are the commonly used stabilization processes?
...Which techniques are used with turquoise?
...Which techniques are used with opal?
...How can one recognize a treated piece?
The term stabilized is most often used when refering to the process of
hardening Turquoise and like materials which are too crumbly or soft
to cut and polish.The process is done in an autoclave where resins are
injected under heat and pressure.
A similar process is used with the dust of these types of materials to
press it into a cuttable block.The best test is to touch the material
with a hot pin.You can smell the plastic on a treated piece.
More interesting to the small lapidary is the process that I will call
fracture filler.This is actually an intregal part of the lapidary process
when working with Emerald or certain Opals.
First I will mention the commerical product called "Opticon" Which is
a two step filler which seems to be like an epoxy and water Glass mix.This
is a often used filler manufacutured by Huges Associates, Excelcior,
Minn that you will find in all Lapidary supplies.
Now Epoxys you will find very useful as fillers of small pits or cracks,and
most effective to use as a backing to stabilize a fragile piece throught
the sawing and grinding process. Best for this is that gray plumbers
epoxy applied across the back of the slab.
Water glass is a good penetrant and sealer. This is very good to hide
internal flaws. It is just as effective as oil to show color and hide
the flaws, except more stable as it actually sets up like a glue.
Lastly I want to mention Canadian Balsam,which you will find very useful
as a fracture filler. Pure Balsam is a little complicated in the application,as
one needs a vacuum/pressure & heating unit to apply. This can be homemade
with parts under $100 (excluding compressor). I am testing now a variation
of just Balsam sold to apply slide covers called "Paramount". This is
Balsam thinned with Toulene,and with chemical additives to stop the yellowing
that can occur with time and the growth that can appear also with time
as Balsam is an organic substance.
There is a lot more of these types of "mother nature" fixers. But these
above are the easiest to obtain, are non-toxic and quite effective.
Voice Mail/Fax: 201-333-6332
Most common method I'm aware of is using a 311 (two part) epoxy and acetone
Epoxy type: 330. Two parts, one hardener, one resin. Water Clear Epoxy.
Acetone: One Pint.
Mix both tubes into Acetone, real well. Allow stones to steep for 7-10
days. Swirl brew around about every other day (don't know why, but that's
what it says!). Remove and let set for a minimum of one week prior to
jar sealed and it will last quite a long time. KEEP IT SEALED! And in
an area that's cooler than my back yard during the month of July. Places
NOT to keep it; near the water heater or other sources of heat that could
either sparks or open flames (acetone is very combustable), where the
children can find it, if you're still blessed to have them in the house. "Daddy!
Look at these beautiful blue rocks I found in this jar!", goo dripping
from their fingers, on the wife's carpet, trailed through the kitchen.
Trust me, no one's going to be happy at this point! Remove stones from
soup. (Kitty litter scooper works good as long as the mouth of the jar
is wide enough, and it's not currently being used for it's designed task.)
Place extracted stones on a surface that no one's going to mind if it
gets a little crudded up (wife's china, DON'T DO IT!). Let dry another
week, have fun!
Why stabilize? Seen many an awesome turquoise gem that was full of cracks,
pits and the like. As long as it will polish, and it's turquoise, it's
a gem. Problem is, most material on the market is to soft to cut, thereby
won't take a polish. The Stabilizers harden the material enough to allow
the Zam to do it's job. One of the beauties of turquoise, no one cares
if it's calibrated, or if there's rough spots in the stone, or if one
can't comb their hair in the reflection of the polish.
How does one tell if it's been stabilized? Rough form: Plastic like substance
surrounding the stone, easy. Cut form: Not so easy. A raw turquoise nugget
will tug at your lip when you kiss it. This property is deminished when
stabilized. Most cutters don't polish the backside of the stone, freak
'em out, give the stone a kiss on the back side. If you feel an appreciable
tug, probably not been stabilized. Light pull means more than likely
stabilized. Should this happen to you, look them in the eye and say "stabilized".
Walk away. Watch them from a distance. See if they don't do the same
thing! I love gem shows! It can be so entertaining! Polished areas don't
give the same effect, so if the stone is also polished on the back side,
your guess is better than mine. Off topic slightly. Chrysocolla will
do the same thing, except it will try to rip your lips off your face.
Difference between the two stones? Duct and scotch tape.
Sorry for getting long winded, Hope this helps some.
I'm not familiar with stabilized opal, but the process for turquoise
is designed to remedy its tendency to be porous and change color over
time. It usually involves impregnation with polyester resin, with or
assist. Often a dye is introduced as well- this can sometimes be recognized
by its overly blue color. One can generally smell the polyester when
cutting the stone; I'm not sure how to non-destructively test for stabilization
a stone that's been set. I've heard that the very finest grades of turquoise
don't need stabilization, but most of the material I've worked with (even
the expensive stuff) seems to have been treated this way.
Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff
I asked a commercial processor in Tucson how he did his stabilizing and
was told that he used the same polycarbonate that is used in airplane
windows. He would not go into details but I would assume this would be
done at an elevated temperature and pressure. There are certainly several
to do it and the results vary widely, I have some you can carve with
a knife and some that will scratch glass.
Not always true, sometimes it is tumbled clean. Since natural turquoise
is sometimes tumbled also, it can be a challenge. Best bet, buy from
someone you trust or don't pay more than stabilized prices to someone
you don't. If
you cut enough of it you do get a "feel" for it, most stabilized turquoise
just "looks different" but even experts get fooled sometimes.
What you are feeling is the porosity of the stone absorbing the moisture
from your lips. With a well stabilized stone, you will get no more absorption
than any other piece of plastic. True gem grade turquoise is solid enough
absorption to be virtually undetectable. I don't think you will see any
of this grade of rough at a gem show, at least I have not seen any in
California, Quartzsite or Tuscon.
Bottom line, if the Turquoise is set, you will be hard pressed to tell
the difference in good material without testing. Again, buy from someone
A little different story here (from turquoise). Both turquoise and chrysocolla
come in a range of hardness from chalk to 6.5-7. But chrysocolla is copper
silicate, with the hardness varying with the silica content. As the
hardness approaches 7 the absorption approaches zero (it becomes chalcedony,
and the price becomes impossible :-( ).
I do not know about Louisiana opal, but mentioning sugar solutions and
a crock pot reminds me of the treatment of Andamooka (Australia) opals.
A book is available which describes the treatment of these opals. Its
title is ALL ABOUT ANDAMOOKA OPALS, written by Emory Ligget, and available
for $5.00 from him at 1851 West Ehringhaus #121, Elizabeth City, NC 27909,
(919)264-4367. Many of you may have met Emory at shows, selling opals.
Also, from The Lapidary Journal Index, I find the following possibly
..Louisiana Opals, Moore, Gary: "Elusive in Louisiana"
..Stability of Opals, "Opal" 86:10:16
.."Opal Treatments" 89:06:44
.."Treating Opal Matrix" 76:10:1787
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