I'm fairly new to the world of silver jewellery and trying to
solder a 10 x 8mm bezel setting to a 2" diameter backplate using an
Am Tech Micro Torch without success! The solder just doesn't flow,
is it maybe because I'm using too small a torch? Can anyone help?
Yes, the reason is that your torch is too small. Silver has the best
heat conductivity of any metal, used in jewellery. Process of heating
a metal, has a point of equilibrium. Torch adds heat to metal. At the
same time, metal gives heat away to surroundings. Torch should be
able to supply enough heat to overcome tendency of metal to cool off,
and more to raise temperature to the required level.
Another way to look at this, is like filling a bucket, which has a
hole, with water. If hole and pipe, which supply water, have equal
cross-section; it would be impossible to fill such a bucket with
Soldering is the same. In order to raise temperature to required
level, a torch must supply enough heat to compensate for the loss,
and add some, at the same time. The heat loss gets larger as
temperature raises. With small torches, once some level of
temperature is achieved, no further progress is possible, because
head added is equal to heat lost. In another words - an equilibrium
for particular torch/ metal combination, has been reached.