Casting

Now that the burnout is complete, and the molds are sitting in the kiln at 900F,

I am ready to vacuum cast. I fill the crucible with bronze,

in this case I have salvaged silicon bronze from my last casting:

these are sprews and sprew cups that I have cut up and sand

blasted to get rid of any foreign material.

I have a propane burner, providing a constant heat, into the fire brick oven.

I then heat the bronze with a rose bud on an oxy/acetaline welder,

until the bronze is molten at around 1900 to 2100 F.

I remove any slag from the top of the molten metal with a steel rod and

open the kiln to get the mold.

I remove the mold from the kiln and place it in the vacuum caster with heat resistant mittens

and then make sure that the heat resitant rubber seal is snug with the steel flange on the mold.

The large part of the mold desends into a vacuum chamber and the steel flange sits on a rubber "o" ring

to create a seal so that the vacuum pressure will suck the steel into the mold when I pour.

Now I make sure the bronze is good and liquid, and turn on the vacuum pump on the casting machine,

and bring the molten bronze quickly to the mold.

I pour it quickly into the sprew cap. Once the pour is complete

I turn off the vacuum pump and remove the mold from

the rubber seal as soon as the bronze is no longer molten.

In this picture I have added more bronze to the crusible again and melted it.

Here I am removing the slag from the top of the molten bronze with a steel rod,

and reheating.

The next mold is for longer pieces. I have welded a steel tube

onto the top of a vacuum mold so that I have more length in the mold.

Once the bronze sprew cap is at a black heat I quench it in cold water.

This blasts off the investment solution and aneals the bronze somewhat.

It is quite a powerful moment when the mold

is screaming and bubbling under the water and

then you draw out the bronze to see if it filled or not.

In this case I had a succesful casting.

Once the bronzes have dried I sand blast them if I'm planning to patinate them,

or if not I clean them with a fine wire brush.

Here they are sand blasted.

Now I cut the sprews off with a jewelers saw and fit them to the blade.