Edward, I am also curious about melting gold into the
depressions of platinum and wonder if you have had any luck in
doing this with other metals.
You can fuse just about any metal to platinum due to its high
melting point. You can use any color of gold. I started with
silver and then tried gold. It is easier to remove silver with
nitric acid from the platinum to reclaim the platinum.
Also, can anyone elaborate on
Bi-metal casting. I read the article in AJM regarding this but no
mention of using silver as the metal to be cast- other than
in an invested flask with 2% boric
You can Bi-metal cast with silver, copper or any other metal use
for jewelry but the draw backs are oxides that form between the
two metals. The use of boric acid added to the investment to
protect the metal from forming oxides. Just as we use a
boric-acid -alcohol solution to protect the item from oxidizing.
There is a special investment used for stone-in-casting to
protect the stones during casting, this investment contains
To ensure a good bond you should drill into the metal item or
into the wax creating metal plugs that will fill when cast. This
will make the mechanical bond between the two metals. You can
also take a wire ball the end up and solder it to the ring to
create a stronger bond. Soldering the two items after casting is
also expectable to ensure the bond. I tend to solder after
casting just to make sure of the bond, it also makes the seam
between the two metals look more fluid.
I have no clue as to how the boric acid is going to help
the bonding of the two metals (does it create a reducing
atmosphere in the flask and if so- isn’t that counter productive
to a good burnout of the wax?) -I just read that it can be good.
The boric acid does not seem to be counter productive to the
casting process it is used to reduce oxides that will form on the
metal during the burnout process to allow the two metals to
adhere to each other. If you are casting gold, silver you want a
reducing atmosphere during casting.
Edward J. Friedman
The Revere Academy of Jewelry Arts, San Francisco