Dating a sculpture
A plaster mould is created layer by layer around the wax model. The surface finish or patina is created using acid and wax.
The mould with the model inside is fired in a kiln. For centuries sculptors have used stone for figurative carvings and ornamental architectural work.
Another cause of damage to wooden sculpture is woodworm.
The holes and burrows that woodworm causes are often visible on the surface of older pieces.
Walnut was used in Burgundy and France, but in Italy, Spain and the Alpine regions pine or poplar were more popular. The design is drawn on a split tree-trunk, the size of which usually determines the dimensions of the finished sculpture, though extra sections can be pieced in.
The form of the sculpture is roughly carved with a broad axe and then shaped with tools such as the narrow axe, flat-headed chisels, gouges and skew-bladed firmers (a kind of chisel with a hooked end used for cutting folds in drapery).
Claw chisels have serrated edges that mean they arc capable of rapid but controlled removal of material.
Lost-wax casting is a complex process using wax models.
In the 'direct' method, the original wax model is used and therefore destroyed. Hot wax is pured in to form a thin layer inside the mould This is repeated until the wax is the desired thickness.
Different types of limestone were employed all over Europe, and alabaster was popular in England, northern France, the Netherlands, Germany and Spain.
The heaviness of stone makes stability an important consideration.
Bronze is an alloy of copper and tin, and often also contains lead or zinc.