BronzeSite Sculpture Formulas

Sculpture Formulas

Derek Kerslake
©July 1998, April 2001.
by Derek G. Kerslake

Modelling wax (measured by weight)

I have used this formula to make portrait medals. It is a very responsive and accurate medium.

50 parts bees wax (from bee keeper , hobby or candle supply shop)
40 parts paraffin wax (hardware store)
7 parts petroleum jelly (Vaseline from drug store)
3 parts anhydrous lanolin (from the pharmacy)

Heat the ingredients in a double boiler or crock pot. Do not place on direct heat because the wax is flammable, remember candles are made from wax. I use dark brown candle wax colorant to darken the otherwise yellow wax; Note however, some colorants will actually modify the workability of the wax, so test a small amount before coloring the whole batch. This modeling wax becomes more pliable as the hand warms it. You will also notice the malleability improves with repeated heating and cooling.

This wax can also be used for the wax component in Never-dry Modeling Clay discussed below.

Investment plaster (measured by weight)

4 parts silica flour (flint silica from ceramic supplier)
1 part plaster of paris (hardware store, building supply, hobby shop or ceramic supplier)

There are many different types of plaster varying in strength. For larger works requiring minimal surface detail, plaster of paris is OK, for high detail in portrait medals, use a plaster with a higher PSI rating.

Mix the silica and plaster in a clear plastic garbage bag by closing the bag and rolling the mix thoroughly. Wear plastic gloves to protect hands from the caustic plaster of paris and a dust mask to avoid inhaling the silica and plaster dust. Now the investment plaster is stored in a dry location until needed.

To prepare the liquid investment for pouring around your wax model, mix:

1 part water
2 parts investment powder described above

Note that plaster is always added to water, never add water to plaster - it will weaken the plaster considerably.

Slowly add the powder to the measured water at room temperature, let it stand without stirring for 3 minutes, stir for 1 minute and fill the investment flask, pouring the mix in slowly to avoid disturbing the wax model. More on Plaster Investment.

Bronze alloy

I purchase my metal from a yard that recycles metals, melts them and blends them, to make various alloys. This metal is similar to an alloy called gun metal. There are over 300 known copper alloys, many of which are called bronze. This one I use exclusively.

88% Copper
6% Tin
1.5% Lead
4.5% Zinc

Never-dry Modeling Caly (Soft Formula)

Modeling wax............................500 gms..................................250 gms.
Raw Linseed oil.........................250 mls...................................125 mls.
Vasiline....................................200 gms..................................200 gms.
Kaolin clay..............................1400 gms..................................700 gms.

The above formula makes a soft clay like material which does not dry out regardless of the amount of handling. The scent is unusual but not unpleasant or strong. Never-dry is soft enough for children and hands which find manufactured synthetic clay too hard.

For more on making your own modeling clay visit United Artworks.

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Derek Kerslake