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Curing Crazed Opal


#1

I have a crazed opal that I need to do something about. Has anyone
used Opticon? Does it work? Is there any other remedy? Help!


#2

Richard

I have used Opticon and it has worked for the stones (mostly quartz
based) I use it on, I have not however tried it on Opal. The process
I use is to soak the stone in a covering of acetone to make sure all
oil is gone, then heat my stone (below 200 F and watch for a thin
line to appear around the crack, if it does you still have oil and
will have to wash it again), use a nail to put the resin on it
following the crack, allow the stone to cool drawing the resin into
the crack. Wipe off the excess resin, warm the stone to touch, then
apply the hardener with another nail. Letting this sit for 10 minutes
or until cool and then wipe it off.

The other method on the instructions is to mix the resin and
hardener, apply to the warmed stone and allow it to soak in. I
suspect it will work, but for me cleaning would be harder since when
performing these actions I am also doing something else and I don’t
always make it back in a timely manner.

For any residue that sticks on, most the time it will wipe off using
a rag, on soft stones I have used a 1500 grit damp wet and dry by
hand to get it off and then re-polished. Careful on a mat or
semi-gloss finished stone, perform this action before final facing.

I suppose you could use stir sticks, tooth picks or whatever you
find handy, I happened to have nails, they make good dop sticks for
working small stones, stirring epoxy, wedges, spacers and so on.

Bummer on your Opal, let me know how it works. If the cracks are
very very small, wait for another post. Someone may know of a product
which gets thinner. Opticon gets thin when warm but I don’t know if
it will get thin enough to get into extremely fine cracks and it
would be a shame to plug the cracks with the wrong stuff. Try and see
which will get the thinnest for you and then go with that one.

Terry


#3
I have a crazed opal that I need to do something about. Has anyone
used Opticon? Does it work? Is there any other remedy? Help! 

I’ve used Opticon on crazed opals with some success. My best results
have been by placing the opal, covered in resin, in a casting vacuum
that pulls 25 in/Hg for a few minutes, then brush with hardener.
Second to vacuuming, heating gently at 250F in a toaster oven yielded
good results. I put the resin-covered opal in the oven while cool,
set to 250F with the door propped open with a bit of aluminum foil to
help with thermal shock. After two hours, ramp the temp down
gradually over another hour and leave in place for another hour or so
to cool. Finish by brushing with the hardener.

As is usual with opals, anything can and will happen. Some have
reacted well to Opicon, others have not. In every case, the opal was
a cutomer’s or friend’s. I never have, and never will, Opticon an
opal unless requested to do so. If I suspect the requester is going
to resell the opal as untreated, I refuse.

I’ve heard of some people using UV curing glues with some success,
but I haven’t tried it. As a card-carrying opalholic, I have plenty
of crazed stones lying around, but I just can’t bring myself to
experiment with them. I simply bring them out every now and then to
enjoy how beautiful they still are even when crazed, and think “Yep,
that’s opal - ya pays yer money and ya takes yer chances.”

James S. Duncan, G.G
James in SoFL


#4

I have three crazed Opals that are worth saving if the Opticon works.
I will be watching your question very close.

Stephen Wyrick


#5

Several years ago I wrote an article that notes work by Dr. Lippman,
an opal enthusiast, who experimented with a a polymer, CR39, to
"mend" cracked opal. I suggest that anyone contemplating using
opticon or any other polymer take a read. The article can be found at

http://www.secretsofthegemtrade.com/articles_10.htm

Richard
www.rwwise.com

For Information and sample chapters from my new book:


#6

There ain’t no cure for the crazed opal.


#7

Hi,

My instinctive response to the “curing crazed opal” is to say “can’t
be done.” Those cracks are so extremely minute already, and they
propagate on an atomic scale. So no large-molecule polymer filler
seems likely to get all the way in there to the very tip, which is
where the active zone is, from which the crack will grow.

That being said, if I remember correctly Orange County CA opal
cutter Stan McCall (who I believe is on the Orchid list) claims to
have a process that can rescue crazed opal. I know Stan and he is
exceedingly capable and conscientious. Stan may respond to your post
himself; if not contact me off list and I’ll give you his phone
number.

Cheers,
Hans Durstling
Moncton, Canada