and foot- bellows operated.
Mouth blow pipes are pretty limited due to the amount of heat
one pair of lungs can support. You should be able to purchase one
from an international supplier like Schmalz or Karl Fischer in
Pforzheim, Germany. Or you can make a basic model to try this
out, using a length of brass tubing (2-4 mm diameter by about 30
cm long [1 foot]). Solder the outlet end closed and drill a very
small orifice in it (about 0.5 to 1 mm should work).
Some blowpipes incorporate a larger reservoir area within the
pipe, which makes it look like a snake after it has swallowed a
rodent. The idea is to blow a very small stream of air across a
fuel-only flame, increasing the oxygen content, and increasing
the heat, while also directing a very small flame to a very small
seam. Light an alcohol lamp and blow across the flame,
experimenting until you find the point at which the flame is
blown sideways and looks like a blue arrow. The tip of the arrow
is the hottest part. If the flame is directed to a charcoal
block, the heat is retained and can be built up enough to solder
something larger, like a ring. Without much practice you should
be able to solder a jump ring. Beyond that, good luck.
While not precisely qualified as a “blowpipe,” foot operated
pump bellows are available which can be hooked up to the air or
oxygen inlet for a torch. I used this exclusively as a goldsmith
in the workshop of Klaus Ullrich in Germany in the 70’s. (Note:
Professor Ullrich was a brilliant master goldsmith and master
silversmith who, sadly, passed away in 1998.) This kind of
apparatus works very well. It is versatile and allows a kind of
precision control that can be compared to the pump (Archimedes)
drill under discussion a few days ago. Both break a complex
operation down into very small increments, and thereby increase
control. Each time you pump your foot you regulate the amount of
air forced into the flame, which affects its size and
temperature. Several very skilled artisans prefer this method
even today, Hratch Nargizian and Abrasha, here in SF, among
them. These too should be available from the same two suppliers
mentioned above.
Alan Revere
Revere Academy of Jewelry Arts
San Francisco