Greetings All In having read your posting I instantly thought how
different the method you use is to the one I have been using. If
nothing else it shows how forgiving metal can be. Rex, please do not
take offence at this posting, it is meant as alternatives to use, not
as a correction to your posting. Input from a refiner would be
The secret is to have the highest melting point metal completely
molten and liquid in the crucible first, and then carefully add the
second-most highest melting metal in small pieces so that they are
completely dissolved into the first highest melting point metal, and
This is almost the opposite of what I’ve found to be useful. I had
occasion to speak to a refiner who had retired and his way of mixing
the metals was to put the Zinc on the bottom of the crucible and this
was followed by other metals in order of their reaction to oxygen.
This didn’t work for me.
In practice I found that by mixing the lower melting temp. metals
together first then slowly adding the gold and palladium until all
where liquid works well. There is an exception to this (isn’t there
always?) and that is Nickel, it resists being assimilated into the
alloy, so I usually melt it with a small amount of gold and copper to
get it to alloy more easily.
Alternately mix the lower temp. metals, pour into an ingot mould
(basically making a master alloy), then mix the higher temp. metals
Palladium, Gold, Nickel ect then reintroducing the alloy of low
melting metals.Mixing the lower metals together zinc silver and copper
is to get the zinc into the alloy and not the atmosphere. The reason
for not starting the higher temp. metals first and adding the lower
progressively comes from the fact that the final alloy will melt at a
much lower temp. than the higher temp. metals, so in effect the
metals are being over heated. Somewhere along the line I remember
reading that by overheating the alloy it will destroy or damage the
grain structure, which in turn may cause the resulting alloy to crack.
, last of all the zinc which will flash
This can be prevented to a large degree by using the above method for
melting, ie making a master alloy first and then adding the precious
metals. Carefully warming the zinc under the silver and some copper
will help stop the zinc being lost, as it won’t flash but as it fumes
it alloys with the other metals. At times I melt a small amount of
silver on one side of the crucible and then allow the zinc and copper
to touch it, this too can prevent large losses of zinc. There will
always be a certain amount of loss. Only by experimenting will you get
the mix/technique right for you, the reader.
The zinc seems to serve no other purpose except to ensure a
A really good source of on alloying metals and the use of
zinc is the book " Santa Fe Symposium on Jewelry Manufacturing and
Technology 1989" Available through Rio Grande. Look in the section on “
Cadmium free gold brazing alloys” pages 179 to 207. You will have to
search for the sections involving zinc.
These days as time is much shorter for me, I tend to use the master
alloys made up by refiners and “just add gold”. The master alloys we
use have no nickel in them and I use nickel only if we need an alloy
that is used for shanks. Generally we use 3-5% Nickel as a maximum as
some people have an allergic reaction to nickel. Yes I realise even in
these amounts some people will react, but that is another string that
someone else may like to comment on.
In conclusion the main thing is to experiment with small amounts
until you find the right methods for you.
William Russell in Sunny Nth Queensland, blue skys and white beaches.