Treating Matrix Opal the American Way
The following story was written by the man in the picture above, our long time friend Uncle George Bucholz.
See another story by Uncle George
You have probably read a lot about the Aussie way of treating
Matrix Opal and I am sure it is a great way to do the material and
it will give great results. I have never treated Matrix Opal
the Aussie way. No matter, I get great results. I have
been treating Matrix Opal since 1982 and I have some of the most
beautiful Matrix Opal you will ever see.
At the end of this epistle I will tell you how to get rid
of your used acid.
Before I tell you how to successfully treat Matrix Opal,
I want to stress to you to get the best material you can afford.
You want quality not quantity. I stress this. Any rough opal
costs a lot of money, your seller knows this as well as you
do. He is not going to make a mistake and slip in a high priced
piece of opal. He also can't afford the mistake. If you want
to be satisfied with what you get in the final result after all
the preparation and the treatment, then you must get the best
matrix opal you can afford. A few beautiful stones are much
more salable and make better jewelry than a handful of poor
quality. You want QUALITY not quantity.
Now the supplies you will need.
[ 1] ---- 1 small ceramic crock pot..
My crock pot does not even have a heat gauge on it for various heats.
I adjust the heat by moving the lid a little crack wider or narrower
any way to keep under 190 degrees Easy to do.
I drilled a small hole in one side of the lid, , close
to the rim, just big enough for the meat thermometer to stick
down into the pot so I can check the heat to keep it about 180
degrees, while i am cooking the stones.
[ 2] ---1 Meat thermometer
The small round head with the metal stick body that comes in a long
[ 3] ----1 copper tongs about 12 inches long,
or if you can get stainless steel tongs about the same Just great.
I have the copper ones.
[ 4] --- 1 small ceramic electric potpourri pot
[ 5] -- 1 Large mouth Mason jar -- quart size.
This is the old fashioned kind. The one who's seal is a rubber ring and
closes with a galvanized wire snap at the side. This is
important because this is the jar that is going to hold the used
Acid after your job is done.
[ 6] ---- 1 stainless steel strainer
Must fit and cover all the opening of the Mason jar if possible.
[ 7] ---- 1 plastic container of Battery Acid
Your nearest battery store that specializes in Batteries will probably
give you a plastic container of battery acid. Ask him.
If not then buy a small container of the acid. Not expensive
[ 8] --- 1 box of Baking soda
I do a lot of treating so I get a big box of baking soda from Costco or Sams
[ 9] --- 1 box of latex gloves A MUST HAVE
 ---- 1 Large ceramic pie plate with raised edges to
hold the potpourri pot. I was lucky, I bought a ceramic pizza
pie plate from a 2nd hand store for 1 dollar.
 ---- 5 lbs of granulated sugar.
I use the Hawaii stuff , never tried the beet sugar.
 Safety glasses
 fairly large ceramic cereal bowl.
When I started I didn't know you were not supposed to use battery
acid, but I couldn't get pure sulphuric acid, so I
bought battery acid and never looked back. Much
easier to use, and not nearly so dangerous.
The first thing I do when I get a new supply of rough rock. I treat it for 3 or 4 days to color it so I can really see what I have and where I should make my first cut.
I have found trying to look at an untreated rock in most instances will not show you the true colors for you to make your judgement.. I try to start the following on a Saturday or a Sunday and then I can do the acid treatment at my leisure.
Fill your ceramic crock pot about 1/2 full of water,
add 2 big cups of sugar. It has to be a quite heavy syrupy
mixture Plug in and Heat until dissolved. Then add your stones.
Now put your thermometer down the hole in the lid, just crack the
lid a bit and and watch the temperature rise till 180 degrees.
That is the temperature you are striving for. Stir the stones to
thoroughly dissolve the sugar. I control the temperature with
the lid. I keep adjusting the lid every hour or so until
this temperature is steady.
Don't worry if the temperature does go over 180 degrees Just so long as the temperature doesn't go over 190 You don't want the water in the rock to boil, and it can, if the temperature gets too high.
Keep watching this for the next 3 or 4 days, put water in to the same height, as it evaporates. I do this watching and adding every morning and evening, Stir the mixture at least 2 or 3 times a day. You are making stone soup. However don't ever try to eat any of it. You can't cook it soft enough.
On the 3rd or 4th day, I drain all the
syrup out of the pot and take the pot and the stones into my
shop where I have my potpourri pot sitting on my pizza pie plate.
DO NOT HANDLE THE STONES WHILE DRAINING THEM If you do, you can
leave your fingerprints on the stone and it can show up on the
I pour the stones into the potpourri pot, scraping out the
ones that stick to the crock pot. Then I put on my latex gloves
and my safety glasses.
WITH MUCH CARE :
Then pour the
battery acid into the potpourri pot until the acid is about an
inch above the stones.
I TAKE GREAT CARE IN NOT PUTTING MY HEAD ABOVE THE POTPOURRI POT WHILE DOING THIS SO I do not breathe in any of the acid fumes.
I then stir the stones with a wooden stick
or my copper tongs, to loosen up the stones that are sticking
together from the sugar. I plug in the potpourri pots. The
potpourri pots have built in thermostats so they will get up to
about 160 degrees which is just fine with me, I make sure there
are no ways a light or a spark can ignite any fumes.
Now get out your cereal bowl and put a couple of tablespoons full of baking powder into it. Fill it about half full of water and stir till dissolved. Put to one side.
I then go about my ordinary chores for about 3 hours and
then I stir the stones again and add more acid if needed.
YOUR SAFETY GLASSES AND YOUR LATEX GLOVES EVERY TIME YOU DO
ANYTHING WITH THIS OPERATION. AND DO NOT BREATHE OVER THE
POTPOURRI POTS AND DO NOT LIGHT A FLAME ANYWHERE NEAR THIS OPERATION.
THE ACID WILL TURN BLACK DO NOT BE ALARMED
THIS IS THE ACID EATING THE SUGAR.
At this time it will look like nothing is really happening to the
stones, but it is happening, I can assure you. Be Relaxed !!
This is a very relaxed operation. No Worries Mate
After about 6 or 7 hours I will look at my stones and I will see some of the most beautiful colors you can imagine. I usually take the stones out of the acid at this time but I will at times leave them in the acid for another hour or two. There is just no hurry. The acid will not touch the opal at all . It will only deepen the black in the matrix. I have by accident left stones in acid for over a year and no damage.
You will also see that the acid has thickened and covers some of the opal so it may be hard to see the colors. Again no worries Mate. The thickness is from the sugar that the acid has been eating. It has not been dissolving the stones.
All, this has been done with latex gloves and safety glasses on !!!
I pull the plug on the potpourri pot .
I put my Mason jar in my ceramic plate. I put the strainer on top to cover the opening.and having my latex gloves and safety glasses on, I carefully lift up my potpourri pot and pour the acid into the strainer to expose the opals. If I spill any acid it will be caught in the plate so there is no danger of hurting something I shouldn't hurt. I dump my opals into the strainer.
Some of the opals may be caught on the sides of the potpourri
pot If so, I can take them out with my latex gloves or I use a
wooden stick. I prefer the stick to the gloves. I do not want to
splash myself at all.
Now all is simple !! I will put my opals slowly a few at a
time, into the baking soda water bowl. It will foam and fuss
This will neutralize the acid. I Leave them there for about 10
minutes, then I can pick them up and look at them.
Now no fires, no cigarettes no sparks. To neutralize the acid
I put a small spoonful of baking soda into the acid in the mason
jar Do not close the lid Let it boil. I continue to do this
until there is no more boiling. I put at least 2 more spoonfuls
in and let it set for a few days, then I put another spoonful in
and let it set some more days. I consider it as being dead and I
can then flush it down the toilet. I flush the toilet a couple of
times more to clear it from the pipes.
Some rocks are very hard and will require several treatments to
finally color them. For my successive treatments I go from
Saturday to Saturday and do the above. Gradually there will be a
great change in color and you can be rewarded with the most
beautiful opals you will ever see. Takes a lot of patience for
the reward. I have treated some stones for better than 2 months
this way, week by week, before I get the color I want.
A WORD :
I want to stress the fact that there is a LOT of work and MUCH patience, connected to getting a beautiful stone.
There is a buildup of brown haze over the stone and it keeps getting deeper and deeper every time the stone is cooked.
However, it is a surface haze that obscures the colour flash in the stone.
I take it off each stone by carefully polishing the stone with 18000 diamond grit sanding belt,
under water spray. A person can use whatever the person has just so long as the haze comes off.
And just so long as the stone is not scratched.
I think I have it all here. Good luck BE CAREFUL
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Last modified: July 7, 2007