The Making of Tunguska II

As part of ongoing experiments with expendable molds, I will be making another Tunguska sculpture. As you may know, the Tunguska event occurred about 100 years ago in Siberia.

First, I have brewed a batch of mint tea:

mint tea

mint tea

This is not for drinking. I will be making paper maché and pasting cardboard using wheatpaste. The recipe I have says to add peppermint oil. I don’t have any, but I do have lots of mint, so I am using freshly brewed mint tea, instead of water. One part flour to four parts mint tea, mix well and boil for 2 minutes.

mint wheat paste wheat paste

That gelled quite quickly, after enough heat was applied. It looks like mint pudding. Next I need a bag of sand to use as a base. Tunguska I used a granite cobble, but the sand bag can be removed after casting. This should leave a hollow aluminum shell, with holes in it.

DSCN1451 bag of sand

The next step is to surround the future hole with a cardboard skirt. Trapazoids work well, and they are glued to each other and to the plastic bag.

DSCN1457 bottom cardboard layer

I put my tin can mold over the hole, and cast a “cookie” using paper maché. This was made from wheat paste and paper sstrips that had been soaking for several days.

mold cookie

This process is repeated until the bag of sand is covered. The paper maché is allowed to dry thoroughly.
DSCN1461 multiple cookies where holes will be

The gaps between the paper mache cookies are bridged with cardboard, and taped. A hole is left to attach a foam sprue, made from packing foam and a toilet paper inner roll.
bridges top layer of cardboard

The whole assembly is packed in dry sand, and the sprue is filled with molten aluminum.
cast with sprue cast with sprue

After this cools, the sprue is removed, the sand emptied, and the piece is soaked in water to remove the cardboard. It is then power washed.
DSCN1498 sculpture, ready to mount

Finally, the sculpture is mounted on a cast iron base. This base was once the base of a sump pump. A new hole was drilled in the center, which as then tapped for a 3/8 inch threaded rod.Tunguska II, assembled


Tunguska II The finished work

Tunguska II

Tunguska II

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