Sand Casting

Casting metal in sand is an ancient technology.
The first metalsmiths pored melted bronze into holes dug into a sandy place in the earth. Modern foundries and jewelers still use holes in the sand as recepticles for molten metal. Max is making some kalediscopes from oak and brass. He recently cast some brass pieces he will need , using jeweler's sand. The procedure is as follows: 
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small photo to see an enlargement:

Parts ofmold

1. This photo displays the mold, or "flask," composed of the "cope" and the "drag."

"A" is the top half of the flask. The red material is a fine jeweler's sand crammed into the wooden frame with a sprew hole through which molten metal will be poured.

"B" is the bottom half of the flask. In it is the negative image of the pattern that the molten metal will fill when halves are joined tightly.

"C" is the wooden pattern for the metal piece. It was pressed into the sand, leaving its imprint as a negative space.

Carafe heats metal
2. This electric furnace heats metal to temperatures above 2000 degrees F--making it molten and pourable.

Adding metal to carafe
3. Max adds more brass scrap metal to the furnace as the metal added previously melts down.

Just before he pores hotmetal
4. Max begins the pouring process. He protects himself from possible splatters with safety shield, long sleeves and heavy gloves.

As he pores hot metal
5. As Max pours molten brass, the zinc oxide generated bursts into flame in the open air.

Flames leap from hole in sand
6. After the left side cools somewhat, Max pours brass into the right side. Here zinc oxide burns off after the brass is poured.

Smoking-hot casting is broken from mold
7. After the brass has cooled a bit, Max uses tongs to dig the now-solid casting out of the sand. 
Hot cast piece
8. This second piece came out of the right side of the flask.

Both new castings
9. Both pieces of brass are rough at this stage, but both are uasable. They will be too hot to touch for the next hour and a half.

Polished, unpolished


10. This photo contrasts the brass piece on the left that Max has machined on a metal lathe with the piece on the right, which will look similar once it is machined.

All photos © 1998 by Carol Yoho
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