The Making of Tunguska II

Written by: Daniel Postellon

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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 mache 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.


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.


bottom cardboard layer

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



This process is repeated until the bag of sand is covered. The paper mache is allowed to dry thoroughly.

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.

sculpture, ready to mount

Finally, the sculpture is mounted on a cast iron base. This base was once the base of a sump pump.

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Daniel Postellon
I was born and raised in Pittsburgh, Pennsylvania. As a child, I played on old coal mine dumps in my neighborhood, which were the remains of mines that fed the J&L iron and steel works. Although I had uncles who worked there, I did not pour iron myself until I managed to get to Herman. Minnesota, for their last pour. Wayne Potratz helped me accomplish my first large scale iron casting,which weighed 50 lbs. It was somewhat difficult to find a place to cast iron, until I took a summer program at Ox-bow, School of the Art Institute of Chicago, under Norwood Viviano and Dan Matheson. I later went to the Indianapolis Art Center for a multiple-furnace iron pour, and did a few “rolly molds” under Kelly Ludeking’s instruction. I have built a small aluminum foundry in my backyard, where I can produce maquettes and other small-scale castings.
Daniel Postellon

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