I use sterling silver casting grain metal and once in a while silver scraps get mixed in. Here are a couple of sources for casting grain metal:
http://www.hauserandmiller.com/fab/grain.htmlhttp://www.gsgold.com/casting-grain/casting-grain.htmlI did buy brass to cast with, but that was for the stick bugs that turned out to be too big for my flask. :(
Here are some more pics to help explain the flask orientation a little bit:
The items being cast get fused onto a sprue, which is then mounted into a rubber base
The flask is then seated over the sprued items on the rubber base, which closes one end of the flask. The flask is basically a metal pipe cut to length.
The item is encased in investement, which is basically super fine material very similar to plaster. After the investment has sat for 24 hours and had plenty of time to cure, you remove the rubber base. The button is placed on the bottom side in the kiln. I should mention here that we use a vacuum shaker table to pull all of the air out of the investment immediately after pouring.
Heated to temperature
Husband using borax to clean the crucible before we melt the metal. We also use the borax to burn out impurities in the silver while we melt it
Place the heated flask directly from the kiln to the cradle, keeping the metal heated
Then using centrifugal force it is spun into the flask cavity
Our highly technical set up
Give the metal time to set in
Then quench the flask
And fish your item out of the bottom of the bucket to see if it turned out good
On this one, they didn't all fill in. I put A LOT of items on one sprue though. LOL To ensure a good cast, make sure each sprue is constructed to each item in such a way to allow the metal to flow without much obstruction, make multiple if need be, and don't overload it.