For what it's worth on this issue, this is what I was taught: Air
cool copper a bit before quenching For silver - Size matters! It
boils down to the size of the sizzle in the quenching dish. The
larger and/or thicker the piece of metal, the longer it should air
cool after annealing or soldering before it is quenched. Your
average size earring, pendant or ring can be quenched immediately.
(Although, if it's a very complex construction, I let it air cool
enough that the water only sizzles gently)
I studied top level precious metals metallurgy courses in Germany’s
major jewelry center, Pforzheim, have read widely (Mark
Grimwade-Brynmorgen press book in the works), and translated
Brepohl’s book which has an excellent section on metallurgy.
If you want maximum softness then you quench immediately upon
annealing. You never should see a red glow from your metal when
annealing (in contemporary lighting). Any air cooling beyond actually
hardens your metal (anything containing copper, all copper alloys,
sterling, most gold alloys).
In all cases wait till any glow is gone from the metal. (You should
not actually see much glow at all) Note that if you watch the flame
color glancing off your metal (on the side, next to the metal, you
will see the flame (with any gas system I have found, including
hydrogen) change to a distinct yellow orange when you have reached
annealing temperature (ok, it varies, but reality is you can use this
indicator for almost any metal, including aluminum) then it is
annealed. This is definitly not the dull red glow (that old hack
comes from the days before electric light, when the ‘hearth’ was
literally a charcoal fire in the deepest darkest recesses of the
workshop-the color, in the dark, was the color of concord grapes-if
you see ANY visible glow off the metal today, then you are damaging
your metal). In other words, glowing red is too hot, and so quenching
is not a problem. For best crystal (grain) structure (ok, so you
only care if you are going to work, hammer, deform the metal-if you
are just soldering and are not going to forge, set, raise, chase,
die-form etc the metal in the next step-who cares if it is
Remember- in current lighting-NO VISIBLE GLOW IN TODAY’S LIGHTING.
Indicators: orange flame, Sharpie marker disapears, ivory soap turns
black, flux melts (then you have to get rid of the flux), bamboo
skewer leaves a mark like charcoal)
For gold alloys (except nickel white) Quench immediately upon
annealing (orange flame)
Copper, sterling, bronze, nickel silver, Quench immediately upon
annealing. (note see the articles on argentium for details.
Brass: No glow, and it is okay to wait a bit before quenching, brass
has odd crystal structures as it cools, and a little wait can help.
Steel: heat till glowing orange and cool as slowly as possible.
(heap with kitty litter, leave in really hot kiln, turn it off, come
back hours later)
Platinum: heat it glowing bright orange, and maintain at this
temperature for 30 seconds for every square inch of material, then
Aluminum: orange flame, bamboo skewer looks like drawing with
charcoal, sharpie marker disapears.
In other words, for most of the materials we work with:
NO glow in normal lighting, watch for the orange flame.
Quench immediately to get the metal to maximum softness.