I suspect that this response might generate some controversy, but
here goes anyway.
Instead of fish glue I use cheap hair spray. It helps keep the balls
where I want them and yet is a very clean source of organic carbon.
The same should also hold true for wire because I use it to stick
wire patterns onto sterling prior to enamelling. Fish glue was fine
for the artisans in the past because that is all they had. Any
source of organic carbon should work.
I also use copper carbonate (basic) that I make by adding baking
soda to very well used pickle for cleaning fire scale from heated
copper. Once the precipitate has been created I add household
ammonia so that it turns from blue to green. I rinse the precipate
three times and filter with coffee filters. It takes about three
days to get a batch. My batch lasts a long time and is a lot cheaper
than buying a kilo of the stuff.
I use sterling silver (7.5% Cu). I heat the base and distributed
granules with MAP gas with the nozzle blocked for air; it still
generates a very hot flame. I use just enough copper carbonate to
cover the surface and no more. I have also used the same technique
to fuse sterling chips, saved from engravings for pit enamelling
(champleve), to a sterling surface.
Why use this method? Because it is my understanding that granulation
works best under a reducing atmosphere which can be obtained by
having a carbon dioxide-rich atmoshere over the metal. After reading
the Orchid archives I'm no longer clear about the theory of how the
copper contributes to the fusing because there appears to me to be
two competing theories, and I no longer have the use of a scanning
electron micruscope fitted with an energy dispersive spectrometer to
examine how the reduced copper is dispersed.
In short, I have found that a good spritz of hairspray plus just
enough CuCO3.Cu(OH2)2 (not CuSO4) to cover the piece. I have found
the tough part is having enough guts to watch the stuff sweat just
enough before it all fuses into useless lump.
My source is John Cogswell (1980) Sterling Granulation, in Metals
Technic pp 3-13.
Hope this helps.
ps And to any of you who read my plea generated from shear panic
from what I had just read, I was able to take the course. And
without doubt it was one of the three most interesting and
enlightening courses that I have ever taken, and I have taken many,
many courses. Thank you Charles.