Will, If you want to cast with another metal or object already in
place (imbedded in the wax), two rules have to be observed. The
first is, obviously, that the object imbedded has to have a higher
melting point than the metal poured around it. Imbedding platinum or
steel, for example will work in a gold or silver casting. Imbedding
gold into a platinum casting will not work.
The second rule is that when the wax melts, the object imbedded has
to be held in place by the investment or in will simply drop to the
bottom of the cavity.
Let's say that you want to imbed a platinum sphere into an 18k gold
cast disk. If the sphere is large enough to protrude through both
sides of the wax, the investment will hold it in place when the wax
melts. If it does not protrude through the wax, simply adding a
platinum wire to the sphere will hold the sphere in place by
projecting into the investment. The wire can go through the wax and
project into the back side of the casting, or it can project out the
front. Having it go through the wax will often anchor the sphere
into the cast metal. Having it project out the front will allow the
sphere to rotate once the gold is cast, since the two metals will
not melt into each other. This would give you a "ball and socket"
If David wanted to cast two red gold saddles onto the shank of a
platinum ring, just wrapping the wax around the platinum shank will
not create the strongest bond. I would cut some locks into the
platinum shank, either with a drill or burr, and make sure that the
wax flowed into these cavities. Since the ring shank is so large,
the investment will easily grip it. Sprue the wax as you would
normally. When you break out the casting, you will find the red gold
has cast around the platinum and is held in place by the mechanical
connection of the locks. If you want a seamless connection, you will
probably have to add solder to the joint. And, since platinum does
not oxidize when heated, the pre-polished platinum ring needs only
the finish on the red gold to be complete.
One of the most basic projects you can do with this technique is to
simply put platinum wires into a wax ring, with metal sticking right
through the wax. Cast this in gold, or silver, and you will get a
casting with platinum wires sticking out of it like a porcupine.
Just file the wires smooth to the cast surface, and you have
platinum inlay! With a little practice, you can get quite