HOW TO : bronze casting with investment mold

The following is the documentation of the investment bronzecasting process. Due to my assisting in the process the photos in this post were provided by Lisa McNamara and KJ power   For flask preperation click here

Preperation
-two people are preferable for this process. One to remove the flasks from the kiln the other to pour from the cruible.
- have suitable protection available, full face mask, leather chest and arm protection, high temperature gloves, leather spats and chaps (figure 1)
-for bronze smelting the tempurature required in the furnace is apporx 1145'c
-once the furnace has reached temperature and the bronze has molten the flasks can be removed from the kiln

figure 1

figure 2

prepare the work area around the kiln for ease of access, make sure there is a clear path from the kiln to the furnace. In this instance a prep table to place the flasks on is setup next to the kiln.

some of the tools required for bronze casting, note the box in the top left, which is filled with small bronze  cylinders.

Kiln
Keep in mind that the kiln needs to be 650'c when removing the flasks. So crack open the kiln slightly to let the head escape BEFORE reaching in with a pair of tongs to remove.
For this process a map of the flasks inside was provided to aid in estimates of how much bronze would be needed for each flask.
The flasks were removed in pairs and placed on a tray.
This tray was then taken over to the furnace


Furnace
Flux is added to the bronze to assist in the removal of impurities


Before pouring into the flasks the impurities are scrapped off the top of the liquid bronze with ceramic rod. Once completed the molten bronze is poured into the mold. And allowed to sit till the metal begins to cool





The mold is then quenched in a steel bucket of water so that they piece can be removed. For the lower temperature investment materials this quenching process greatly increases the ease of removal, where as the higher temperature investment materials are only partially effected by this process.



The removal of piece from the investment flask is a low tech method, done by working the investment material loose with a screwdriver until the piece is removed






the final product