You wrote:
G’day; Some of you may remember that quite a while ago I asked if anyone
had >any experience with Niello.
John, I have had no direct experience with niello, but having
just read about the technique I thought I might pass on what I
found. The following is from Ron Edwards’ book, The Technique
of Jewelry.
"In the 11th century A.D., Theophilus made various alloys for niello work,
the primary one being:
Silver 2 parts
Copper 1 part
Lead 1/2 part
and a unspecified amount of sulphur.
(My (Mr. Edwards) experience proved satifactory when I used
sulpher that was twice the quantity of the other three
components, ie 7 parts sulpher to 3 1/2 parts of silver, copper
and lead.)"…
…“To make, melt the silver and copper together and when molten
stir well with a carbon, graphite, or ceramic rod. Now add the
lead, which will melt immediatly. Stir again and remove ant
dross that rises to the surface. In another crucible have the
sulphur which has already been melted or heated, and into this
crucible pour the niello alloy and mix all thoroughly together.
There are some schools of thought which suggest that the sulphur
is not melted or heated but just thrown in. It is really a
matter of experimentation to find out what gives the best
results, but the aim is that all the ingredients must be mixed
into a homogeneous mass. Then pour onto an oiled sheet of steel
or into an ingot mould. On cooloing the lump of niello can be
broken up and ground to powder, then seived through an 80 guage
mesh.”
“When the niello has been ground and washed in distilled water,
pour off the impurities that may float to the surface. Store the
cleaned niello in a stoppered bottle with distilled water
covering it. This will insure that it will remain free of
impurities.”
“To use the niello powder, dry it in front of the kiln or in the
kiln at a very low temperature. When ready for use, the niello
powder can be laid into the recessed areas with a spatula. If
the walls of the recesses are undercut it is a decided advantage,
but if they cannot be undercut it is advisable to coat the
recesses with a weak borax solution to ensure a firm cohesion
when the niello fuses. Try not to overspread the niello as if
the niello is made too hot it will burn into the surface of the
metal and would have to be filed away”
“Sprinkle a little powdered borax over the work as a fusing
agent, and place the piece into the slow kiln at a low
temperature. Watch carefully until the niello has fused and take
it out of the kiln immediately as it should not be overheated or
its lead content will corrode the gold or silver.”
“Should the niello begin to spread or wander, push it back into
position with a hot spatula, and also use this to firm the niello
down if necessary. Allow to cool off and do not quench. File
away any excess but not quite down to metal. Re-heat the piece -
or pass a hot iron over, not on, the work, then with a lightly
oiled burnisher, quickly burnish down the remaining niello until
it is level with the metal surface, which will remove any air
bubbles which may have arisen.”
“…Care must be taken when polishing, as the niello could be
dragged or scoured out. If this happens, wash thoroughly, and
pass the hot iron over the workto re-fuse it.”
I hope that this might be of some help.
Steve Wiser
Steve Wiser
PO Box 938
Santa Margarita, CA 93453
(805) 438-5232