Terrie,
There are several combinations of silver and copper that will
reticulate. Two of the most common are 800 parts of pure silver to
200 parts of copper or 820 parts of pure silver to 180 parts of
copper. There are no other metals involved. You can confirm this in
many jewelry reference books or by sending e-mail to Stewart Grice,
the metallurgist at Hoover and Strong, who has worked extensively
with reticulation alloys.
You will find that rolling sheet reticulation silver is tricky as it
is a very stiff alloy and sensitive to being overheated during
annealing. I hope you have a powered rolling mill because it’s a
very long way from ingot thickness to the 18-24g where reticulation
silver really performs.
During the melt, be absolutely sure that you have a completely
molten mass – there is a wide temperature range during which you
will have some extremely runny metal and some chunks like gravel –
you will feel this with your carbon stirring rod. Do not pour until
all the metal is liquid.
Before you begin rolling, meticulously finish the sides and corners
of your flat ingot. Inspect it with a loupe and carefully file away
any cracks or crevices so that you have a beautifully smooth surface
on all sides. Any little flaw will rapidly develop into much more
serious cracking as you roll the ingot out. You must monitor the
edges throughout the rolling process and remove and smooth all areas
where cracks occur.
Once you have it smooth, anneal it very carefully. Coat the ingot
with borax-based paste flux to prevent fire scale; the flux will
also tell you when you have reached annealing temperature, because
the flux will be entirely transparent and will wet the surface of
the metal [i.e. look like liquid on the surface, not little balls or
lumps]. Even better would be to coat the ingot with Prips and anneal
it in a kiln set to 1200 F. so that you know for sure you aren’t
overheating it. You will have to anneal every few rolls. Take it in
very tiny increments and use the scale on the top of the mill to
keep track of your tightening. I mark my place with a little magnet.
This alloy firescales far more readily than sterling [which is what
makes it work so well for reticulation], and firescale is brittle
and inflexible. It will fracture during rolling and craze the
surface of your ingot.
In order to get a sheet of reasonable size and quality, you will
have to give this process several hours of your careful attention.
As a learning exercise it’s worth doing once, but it is not at all
cost effective to do it often. I would suggest starting a
reticulation fund by labeling a jar on the kitchen counter and
emptying your change into it at the end of each day. In a couple of
weeks you will have enough for a nice sized, pristine sheet. You can
always pay for it by postal money order, a credit card is not
necessary. Refiners will also take a personal check if you are
patient and will give the check time to clear before they ship the
metal. I don’t wish to discourage you in this, but it is really a
time consuming task, and if your time in the studio is limited or
expensive [i.e. lesson time with your mentor], then it is not a good
economic strategy.
You should also call Hoover and Strong and request a copy of their
metals catalog, which is free. There is a nice article in it by
Steward Grice about reticulation that neatly puts all the
in one place. Stewart, a metallurgist with access to a
lab, worked with Andrew Nyce, a retired metallurgist, and myself to
do a careful scientific study of the reticulation phenomonon and the
results, without the mythology [and there is a lot of that on this
topic], are in those pages of the catalog. I think you’ll find it
helpful.
Good luck,
Anne Hollerbach