On Thu, 19 Apr 2007 21:52:11 -0700, in rec.crafts.jewelry C0nnie
wrote:


Hello Peter and Carl.

I was unaware of the copper part. I have bought and watched
(repeatedly) Ronda Coryell's DVD "The Art of Granulation" in which
there is no copper plating of the fine silver she uses. I have
imitated the technique and it has come out quite nicely.

Also had some flubs.

Anyway do you know of her technique? I found it quite worthwhile to
watch and take notes. I enjoy reading about all methods to accomplish
the same result. There are many considerations that may come up in the
future that might change my favorite one.

Hi Connie,

I'm not specifically aware of Ronda's method or DVD. But it's true enough that
copper plating isn't the only means to granulate.

Any technique which will allow the surface of the grains to become liquid long
enough to form a slight bond with whatever surface they touch (other grains, or
the substrate surface) will allow granulation to be done. Copper plating, or
the use of copper salts mixed with the glue, or the raising of copper oxides to
the surface of the grains by repeated heatings, is just one way.

When Littledale published his efforts to reinvent/rediscover the methods by
which ancient granulation was done, in the 30s, I think, his discovered method
was the use of metallic salts added to the glue mix to affix the grains. Copper
salts were the main one he used with the most success, and this is how that
variation of the method has most frequently been taught, but Littledale also
discussed the fact that salts of any metal which would be reduced by heating in
the presence of carbon to a metal, and which would then form a eutectic alloy
with the silver or gold being bonded, could be used. One could theoretically
use a mix of salts which would, upon reduction, give a mix approximating almost
any solder recipe you could wish. The main key is that the method results in an
exceedingly small amount of "solder" at the surfaces, so that delicate
granulation results rather than flooding of the grains with too much solder,
which is what almost invariably happens when actual solder is used.

Using the copper plating method to coat the grains is simply a shortcut over the
use of metal salts, and it's ease of use is the main reason it's been widely
taught. But as I said, it's not the only way.

John Paul Miller, for example, did not plate his grains. Instead, he heated
them in air to raise an oxide layer on the surface. That leaves a copper
enriched surface, and a copper depleted area just under the surface. That
depelted layer is then slightly harder to melt, so the grains are less likely to
melt when granulated, if heating is very closely controlled.

And Elizabeth Treskow is said to have done considerable granulation with pure
gold, using just saliva to adhere the grains. Here theory was that the slight
amount of organic material therein, would carbonize, as does glue mixes used by
other workers, and with pure gold or silver, that carbon would lead to the
formation of small amounts of gold or silver carbide alloying with the surface,
slightly lowering it's melting point over that of the metal itself, allowing
granulation to be done that way. At least that's what i've been told. i've not
seen this published directly by her. But I've seen the "carbide" theory of how
granulation can be done promoted by other writers too.

In truth, there are no doubt multiple methods of doing this. Some methods will
work better for some people than for others. it remains a mystery just how
ancient granulation was actually done, since even with modern work, the
formation of teltale surface alloys that might show exactly how the work is done
simply doesn't happen well, and with old work, diffusion over time of copper or
other metals into a surface mean there's no evidence anymore to show. One can
deduce simply by the ease with which one can accidentally get an excess of
copper on a surface, either by working with old pickle or similar acid
chemistry, along with copper or bronze utensils, or by the probable coesixtance
within a workshop area of other sources of copper, including copper salts, which
might easily have lead to accidental discoveries of a soldering method by
ancient workers.

But even if we knew for certain how ancient granulation was done, it still
doesn't negate the fact that with modern knowledge of metalurgy, and the modern
armament of tools and heating methods and chemistry with which we can work,
there will be considerable options we can explore in doing this.

Still, I'm curious. Can you explain how Ronda does it?

thanks.

Peter Rowe