How is a Bronze Sculpture Made?

Let me show you:

I was contacted by a family interested in having a sculpture made for them.

Together they discussed ideas for the piece. They wanted the sculpture to represent their two lively children.

Familiar with my work, they were not looking for a realistic rendition.

They sent photos of the kids, along with descriptions of their natures.

From this information, several sketches were created for them to choose from. The family picked the one they liked the best, with a few suggestions, the project was started.

A maquette was made, measuring about 12 cm, or 5 inches, tall. The family lives out of state, so it made the idea easier to visualize.

A steel armature was necessary in order to support the weight of the clay, which will be 150 #'s or more. The clay is firmly slapped onto the armature. It is important to get it on there nice and solid so that the clay won't slump down.

Here the clay is beginning to show the form,

the following photo shows the sculpture almost complete.

At first the work always seems to go quickly, it may take only a day or two to reach the first stage.

Then, the work slows down, as the smaller detail is considered. It could take weeks to get it to the final stage. Sometimes a piece has to just wait, carefully wrapped in plastic to keep the clay moist. Sometimes the clay used is a different kind that does not dry. Either way, sometime the piece just has to wait for the next inspiration to arise.

A close up of the faces on the final work.

When the clay work was finally finished, photos were taken so the family could see the sculptures' progress and make sure that they were happy with how it turned out.

The next step is to prepare the mold.

Sometimes the mold is made right in the sculpture studio. Other times the piece is taken to the foundry for all the work to be done in one place.
First a thin metal dam is placed along the parting line. (Where the edges of the mold will come together.) Then the first layer of mold rubber is put on. It is layered on several times until it reaches just the right thickness.

The photo below shows a bit of the final, thick, mold, which in this case is a bright yellow,
with a plaster "mother mold" encasing it, to strengthen the rubber mold, and hold it in place. The mother mold is applied before the mold rubber is removed from the original clay sculpture.

The next photo shows the rubber mold for the front half of the sculpture, lying on the table, supported by the mother mold. The mother mold for the back half is lying next to it.

The next step is to brush a layer of wax into the mold, about 5mm, or 3/16 " thick.
After the wax cools, it is removed from the molds, and all parts are seamed together.

The next photo shows the "cleaned-up" waxes at the foundry. You can see that they are not completely put together. They will get cut apart even farther, depending on how the foundry decides is best, in order to cast it correctly.

Every foundry looks a bit different, and most of them have their own way of doing things, but this is the basic idea, which remains the same.

Here you see the wax sprues, that are used to hold the wax sculpture in position.
The arms have been removed and will be cast separately, as will the legs, base and the girls' leg that was kicking out to the side. All the separate pieces will be welded together after they the bronze has been cast.

The next photo shows the main part of the sculpture with the wax “sprues”.
These will become the channels for the bronze to be poured through, and vents for the air to escape through.

Next, the arms being dipped into the slurry, carefully, to be sure that it is completely covered inside and out. Afterwards, while the slurry is still wet, it is coated with a silicon sand. This process is repeated,several times, on each section of the sculpture, until a shell has built up to the correct thickness.
All the individual pieces will then be put up on shelves to dry and the shells to harden.

Pouring fine silicon sand over the arms of the boy here.

The main part of the sculpture, it's finished, dried shell, is a bright yellow at this point.

The next step, after the shells are thoroughly dried, is to place them in a large kiln, where the intense heat melts the wax which flows down and out and is burned out of the shell.

Because the shell, below, is quite large, it has been wrapped with wire for extra support to keep it from breaking.

This shell will be turned upside down in the kiln to allow the wax to flow out through the sprues (channels).

The furnace, below, where the bronze bars are being melted, soon to be poured into the waiting shell.

This is an exciting time at the foundry. The roar of the furnace, the possible danger.

Some foundries do this with a large audience, music, and great splashing of the fiery molten bronze. Other foundries do it quietly and precisely, with no extra drama.

Either way, it is compelling to watch.

The molten bronze is being poured out of the crucible, into one of the smaller shells.

This next, darker, photo, shows the molten bronze being poured into the larger shell of the main part of the sculpture.

Here you can see the bronze, just after it was poured into the shell.
It looks bright red, like the skin of a persimmon, but it is liquid bronze. It will have to cool for a while, to become solid, then the shell will be broken away.

After all of the parts have been cast, cooled and the shells broken off, the parts are welded together.

Now, you have a bronze casting of the original clay sculpture.

The bronze is the same thickness as was the red wax that was brushed into the rubber mold. The sculpture is hollow. But still very heavy.

The next step is to carefully grind and polish away any imperfections caused
by the welding, and to rework the texture that was lost where the seams were made.

After the artist is happy with how the work looks, a chemical patina is applied to the raw bronze.
In this case, it is a simple outdoor patina, for a pre-aged look.

Large stainless steel bolts were welded to the underside of the base for mounting.

The final step was to have a crate made, and ship "happy dance" to it's new home.
(the title is not capitalized at the request of the family, who love e.e. cummings.)

The entire process started in June of 2002 and shipped in October of 2003.

That’s all for now.