I read that thick metals require multiple annealings for the
effect of the annealing to completely penetrate the entire
thickness. Is this correct?
Complete annealing can require a little longer at the appropriate
temperature for thick metal, but not multiple annealings. Most gold
or silver alloys anneal quickly at normal “torch” annealing temps, so
you don’t normally need to worry about whether it’s been long enough,
only whether it’s reached the needed temperature. Platinum, on the
other hand, anneals more slowly, so thicker metal may need to be held
at that nice orange glow for more than a few seconds, to fully
anneal, though often, even partially annealed platinum is quite soft
enough. If you anneal in a furnace, which can then, with tight
temperature control, do your annealing at a lower temperature but for
longer time, then adjusting the time for the thickness may be needed.
The lower temps that you can practically anneal at with a furnace
allow you to minimize grain growth and surface oxidation or loss of