For 29 years I have studied, practiced and taught “granulation” so
this discussion is right up my alley. I certainly do not have all the
answers but I do have some observations.
Today, we understand the word “granulation” to mean a process, but if
we are to be truly correct, it refers to a type of surface decoration
that is achieved by the use of small granules to create patterns or
texture. There are no records of how the ancients actually
accomplished the attaching of those tiny bits of metal to the base
plates, so we all can theorize from our experience and exposure to
books and museums, and the few historical clues that we do have. One
of those is the name of a copper bearing mineral, chrysocolla, which
in Greek means gold (khrusos) glue (kolla), and which in ancient
times was used in some of the processes of attaching the gold
granules. From what I have read about the analysis of ancient
examples, from many different cultures, more than one process was
assumed from the examinations. Silver was found in some sites, which
seems more like soldering than “copper induction brazing”. So I think
that it would be very difficult to separate granulation and
soldering, and it is my opinion that many of the procedures
accomplished today by soldering were accomplished then by the same
process used for attaching the granules. That process could not have
been difficult, as there was so much produced that is so amazing.
There are still many things that I see but can not replicate, leading
me to the conclusion that there must have been something in their
process that we have not yet found, that is probably beyond our
capability of seeing and understanding as we are of such a different
time.
In the twentieth century, there have been several people who have
redeveloped a process for attaching the granules and all of these are
different and all work to some degree. All of them are similar in
that they use copper in the process, but it is introduced in various
ways. I prefer plating the granules and enriching the surface of the
base. I am able to obtain shiny surfaces on the base and delicate
attachments of the granules. And I like to use .014 granules for
intricate patterning because they allow much more variety of patterns
than even the .016 granules. Of course, it would be uninteresting to
use only one size, so I use all three commercial (actually four)
sizes, depending on the project.
Speaking of commercial granules, that is definitely the way to go if
you are doing any volume of work. They are expensive, but they are
all the same size and all round and the time I save more than pays
the extra charge (although the company that makes them has a monopoly
and really charges more than I think is necessary). For larger -
over .032 - granules I make them by the paillions on charcoal method.
About the diffusion question, I frequently fuse structures, I always
fuse bezels, I usually fuse the bezel to the back, that is, I do not
add any copper. I do not know if that is diffusion, but I am only
using what is in the alloy. Is this granulation? I am using the
copper in the alloy because I do not pickle the components, but when
I fuse/granulate fine silver, I use nothing but heat.
After all my years of close association with this beautiful,
mysterious technique, I have concluded that it is really easy, that
it was always easy, and that the most important element for success,
besides patience, is the control of the heat.
Did I clarify anything, or add to the confusion?? In any case, in my
mind and work it is clear, very gratifying, very demanding, very
challenging and ever-growing.
Incidentally, I read the article on granulation and amber when it
came out and I decided to try to use it in the process in some way.
I ground an amber bead and experimented with the powder in various
areas of the procedure. It did nothing but contaminate the surface
so that it got in the way of the process. I wrote to the author,
hoping to get some clarification as to exactly how it had been used
but I never received an answer. And I have never seen it mentioned
additionally anywhere until now, and this was questions, not answers.
So I have to assume that it was the speculation of a scholar without
practical experience.
Sorry I took so long to get into this. I was out-of-town and away
from a computer.
Jean