There probably is an exact ratio of the wax you are useing (there are hundreds) and the bronze you are useing There are dozens. You will get to discover that ratio. Best quess from this bench is 10 to 1. Is this new furnace a handy melt electric furnace? If so they use a cylinder shaped graphite crucible. Measure the interior of the crucible, construct that cylinder out of heavy paper or sheet metal. Fill the mold with wax. Thats how much was you can use, well maybe. Just because a container can hold 100 anything doesn't mean that 100 can be safely poured from it. Handy melts take some getting used to. Pour some ingot molds first. It's just part of the learning curve. Be careful that the expensive crucible doesn't slip out of the furnace.also remember that you need to have some room to remove slagg from the metal before pouring. My experience with is that bigger sprue bases are best, because they are easier to hit. So some of that large capacity is going to be used by bigger than normal sprue bases. Some models will require a large button to allow to model to draw metal from.
This is just one of those times when experience is going to have to be the teacher. pouring some ingot molds will give you a whole bunch of knowledge. one of which is the capacity of your equipment. Brad

Wax fo the most part hasa specific gravity of 1 and bronze is around 8-9 so there is your ratio. However the furnace holds 100 tOz of what? If it is 100 tOz bronze fine and dandy however if it is 100 tOz silver or other metal then you need to adjust to the ratio of the bronze and the metal the furnace is rated for.

Jim

I use an 11 to 1 ratio but that really does not mean much in real accuracy. When you use new ingot versus scrap you will get differing amounts of slag or waste in each melt. In addition you may be wanting space in the crucible for a piece of glass or Borax for a cap to the metal melt. The sprues, air vents and pouring cup will take up space also. There also is a certain amount of sprue / vent height for gravity pressure needed unless doing the pour with centrifical or vaccum suction. Don't forget to add or adjust volume for any 'shrinkage' bulbs or metal feeding necessities during the cooling process. For me weighing the piece tells me little since I use styrofoam sprues, cup and and air hollow vents. That saves a huge amount of wax but also makes for a sprue that can be melted out with lacquer thinner before the piece even goes in the burnout kiln making the interior have a ready wax escape right from the start. My final solution is to always melt more metal than is needed and pour an ingot with what remains. Of course I am working with a crucible that holds 300# bronze per melt so this may mean little in your case though the principles are the same. On pieces that are pushing the 300# pours I actually do a water displacement test. Also... I have splash missed the cup a few times and dropped off a few pounds in a goof but with the extra amount in the crucible it did not become a disaster.. bpfink