For normal 14K yellow golds, try this process.
Mix some powdered boric acid (from your drug store, or jewelry
supply houses) with some denatured alcohol (shellac solvent in the
hardware store) to a consistancy about like skim milk. Dip your
coil or wire in this (or brush it on) to coat. Either let it just
air dry, or light the alcohol and burn it off. Either way, you're
left with a thin coating of boric acid on the gold. This will
prevent fire scale and discoloration of the wire.
Set your kiln to about 1100 to 1200 F. Leave the wire in the kiln
until the coil reaches the same temperature, which likely will be
just a few minutes. Remove the coil and immediately quench it in
cold water. You can use lower temperatures if you like (down to
about 850 or 900 degrees F, but then it needs to be left in the kiln
a bit longer (a few more minutes usually, or up to 20 minutes if
you're doing this all the way down at 850F) for maximum softness.
The water quench will give the softest gold with yellow golds. After
quenching, pickle the wire in commercial jewelers pickle, or it's
cheaper hardware store equivalent, sodium bisulphate, which is sold as
an agent to lower the ph in pools, spas, and hot tubs. Find products
like "ph-down", or "spa-down". Or just buy the same stuff, slightly
less pure oftentimes, at higher prices from your jewelers supply
store, but save the time running around the hardware stores looking
for the stuff. It's best used mixed with hot water, but can be cold
too, just takes longer to take off the boric acid and any slight
discoloration left over. Annealing at the lower temperature ranges
given also may reduce any tendancy for discoloration/ oxidation
(still with the boric acid fire coat).
If you need a "safer" pickling agent, citric acid (food grade stuff,
usually, though not always so easy to find in the grocery store) also
works, but more slowly. And boiling water will take off the boric
acid all by itself, though it won't affect any residual oxidation
that might have occured.
If the times and temps given seem a bit vague, in part this is
because there are a range of alloys you might have, not just a
single one, and ideal annealing cycles can vary some. But the above
will work just fine with most yellow golds. You can ask your metals
supplier for the ideal times and temps for furnace annealing your
alloy if you wish. They should know, or be able to refer you to the
refiner it came from, who hopefully WOULD know for certain, if
they're any good...
Hope that helps.