I also recommend Ronda Coryell’s DVD on fine silver granulation for
its excellent and comprehensive presentation on fine silver fusing.
However, when copper is used, you are doing "eutectic soldering"
instead of fusing and use different techniques. A kiln is not needed
to bring the back piece up to melting temperature and you can use a
back piece that is thicker than the height of the granule. One
problem I had was that the copper coating (copper plate or copper
carbonate mixed with the glue) often did not completely alloy and
when I used depletion gilding to remove the copper, it often weakened
the bond and granules would fall off.
One solution to this problem is that if the design is first fired on
a thin sheet of steel about half of the copper will be used to
"eutectic solder" the granules together. With glue but without
adding more copper, when this granule unit is then placed on the
back sheet and heated to a “solder flash”, all of the copper is used
up andforms a tight bond.
Use a solderite board instead of charcoal for any granules under
1mm. Sprinkle about 30 same-size fine silver wire clippings on a
flat solderite board. Use a small flame to ball the wires. When all
of the wires are melted to balls, tilt the board over a container to
remove them. I use a Pyrex glass container without water. Many
authors promote the use of a charcoal block - sometimes with channels
or holes dug in or tilted so granules roll off to a dish of water.
However, all of these techniques take more time, the charcoal
degrades with each firing, and when the board is tilted, many of the
granules roll off the board before the granule is completely round.
Also, check the archives for more on granulation.
Hope this helps.