An alloy of copper with other metals (especially with tin) used since ancient times.

Bronze casting:

When casting bronze, artist usually applies the lost-wax technique which is dating back more than 5000 years. It's the best, but also the most complex method of producing sculptures.

Sculpture "The Book Reader" by Ernst Barlachs is shown here as an example:

First, the artist forms a model of his sculpture. It is embedded in a liquid silicone rubber composition. Once the material has solidified, the model is cut out. The liquid wax is poured in the negative mould. After cooling down, the wax casting is removed from the mould, provided with sprues and dipped into ceramic mass. The ceramic mass is hardened in a kiln, and the wax flows out (lost mould).

Now we finally have the negative form, into which the 1400 ° C hot molten bronze is poured. After the bronze had cooled down, the ceramic shell is broken off and the sculpture comes to light.

Now the sprues are removed, the surfaces are polished, patinated and numbered by the artist himself or, to his specifications, by a specialist. Thus, each casting becomes an original work

Designation for an art object (sculpture, installation), which is produced according to the will of the artist in multiple copies in a limited and numbered edition.

Artist's multiple contributed to "democratization" of art as the work was made available and affordable for a wider audience.