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Sealing


#1

I have a Tourmaline with a rather unsightly occlusion at one end
which really detracts from an otherwise very nice stone. I have seen
advertised a product called Opticon which is supposed to seal
fractures. I wondered if anyone can tell me if it might work on my
stone or if they may have other suggestions?

Herb


#2

you can partially “cure” a fracture that intersects the surface;
however this will not solve an “inclusion” ie.e, foreign matter
contained in the tourmaline itself, usually mica, quartz or other
pegmatite mineral. If it is a fracture that intersects the surface,
the fracture will provide a way for the fluid to enter the stone.
Once inside, the fluid will provide “optical coupling” so that the
fracture visibility will be highly reduced. (forgive me I do like
using passive voice when writing)

Opticon is available from Rio, I believe

Mark Zirinsky, Denver


#3
 I have seen advertised a product called Opticon which is supposed
to seal fractures. 

Hi Herb, I use Opticon all the time and love it. I work with Lake
Superior agates, fractures are the rule rather than the exeption. I
have to say, Opticon seems to do the trick, though I wonder sometimes
what it will look like 10 years from now. Im sure it would work for
you too (standard disclaimer-I havent used it on tourmaline)

There are instructions included in the box, a couple things that I
would add: They recomend first washing the stone down with a
solvent (acetone); make sure to let stone sit for a while by
lightbulb so that any solvent in fractures evaporates. I think they
also suggest alcohol, I think that if you go that route use
annhydrouse rather than regular rubbing (Annhydrouse drys up moisture
and evaporates clean, rubbing contains water and evaporates slower)
Also rather than drop stone in hot Opticon, heat stone (lightbulb
again) and then brush Opticon onto fracture. Both these will help
you get good relatively fast penetration. Also, after stone is
treated dont use solvents on it or your fracture will reappear.

While Im here, I might as well ask a question of my own. Could
anyone tell me a good way to make my own charcoal soldering blocks?
Im sure its in the archives somewhere, I just cant find it. You can
answer me offlist at @joe.hanson if you like. Bye, Joe


#4

Herb, When fracture sealing the two most important points to address
are the refractive index of the stone and the sealer and if the
fracture penetrates the surface of the stone.

Opticon is basically made to be the same refractive index as quartz.
Quartz RI = 1.535 Tourmaline RI = 1.640 -1.655 on one axis and 1.615

  • 1.620 on the other. What this means is that the opticon if filled
    the fracture it will still be visible as the RI does not match. The
    second point is that the fracture must penetrate the surface to
    allow the Opticon to be absorbed into the fractures. Without an
    opening the opticon will not fill the fracture.

For a long time I experimented with numerous fracture fillers. I
stopped when it became apparent to me that I no longer was just
trying to improve the stone. The process actually became a
deception. I now recut the stone to eliminate the fracture, sell it
as it is, or put it in my trash bin. None of my stones have fracture
filling that I know of. I type this because I know that the science
has improved to such a point that without a laboratory dedicated to
identifying treatments it is almost impossible to tell a fractured
filled stone from an untreated stone.

Gerry Galarneau


#5
    I have a Tourmaline with a rather unsightly occlusion at one
end which really detracts from an otherwise very nice stone. I have
seen advertised a product called Opticon which is supposed to seal
fractures. I wondered if anyone can tell me if it might work on my
stone or if they may have other suggestions? 

Hi, Opticon is used for sealing open fractures and cracks in stones.
However, it doesn’t have the refractive index of tourmaline (I
believe it’s around 1.52 for its r.i.). You can seal the fracture
with it, and it’ll improve the appearance of the stone, but it will
be noticeable if someone looks closely. However, if you do seal it,
you must inform the person buying the stone that it has been filled
with a resin used for this purpose. To do otherwise constitutes
fraud.

Richard


#6

Joe,

Not sure about ‘charcoal’ blocks but if it is an easy to make
soldering block you need, just mix up some investment and pour it
into a small flat pan. When it dries…instant soldering block!

Some years back, I used to use charcoal bricquets used in BBQ
grills…had to be the plain type…not quick light…they have and
igniter fluid in them. I would rub one against a brick until the
side was flat and then push it into a small can (tuna type) filled
with wet investment. That made a nice soldering surface and when the
bricquet wore out, just pry it out and replace it with a new one. A
bag of bricquets would last a loooong time.

Cheers, from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut1.