Examental

TECHNIQUES

LOST WAX BRONZE CASTING

Two main factors should be borne in mind during the lost wax process: the technical aspect and craftsmanship.

Over time the materials and methods used have reached high standards of quality and each wax casting is treated as if it were an original work of art.

Lox wax casting is undoubtedly the most frequently used method to create large and small bronze sculptures as it can be used with any material to produce a perfect copy of the original.

Making the Moulds:

The artist creates the original model from clay, plaster or another type of material. This model is covered with silicone. Various moulds are made. An opening is made in the rubber mould and the original model is removed.

The Wax Casting:

The rubber mould is thoroughly cleaned out then filled with liquid wax. This wax casting is removed from the mould.

Checking the Wax Casting:

The wax casting is checked by a trained artisan who specialises in retouching wax castings.

Spruing

The best position for the sprues (gates) and air vents is determined as each piece needs these.   In microfusion many complex pieces are attached in the form of a tree

Investing

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The wax casting is coated with a liquid refectory ceramic.

Burn-Out

The ceramic covered mould is fired in a burn-out oven or kiln. The temperature is gradually increased to 750ºC to ensure that all of the wax is eliminated and the shell is totally baked without any trace of moisture.

Preparing for the Bronze Casting

The molten bronze is heated to 1250ºC.   In microfusion brass, silver and bronze are more frequently used.

The Bronze

The molten bronze is poured into the mould through the sprues. In microfusion the moulds are filled and centrifuged.

Removing the Bronze Sculpture

The bronze is allowed to cool in the mould.   After cooling the ceramic shell is broken away in order to extract the bronze sculpture within.

Cleaning the Bronze Sculpture

Soldering

The sculpture is cleaned with water or by sandblasting it. The sprues and gates are cut away leaving the sculpture ready for soldering.

The holes are soldered. The piece is then chased and polished

The Patina

The chased bronze is treated with chemicals (oxides diluted in water in the correct proportions) and heat in order to attain the desired patina. As the shine of the piece is so important, this must be studied beforehand.

Finally the patina is coated with wax.