Metal Casting

LOST WAX METHOD OF METAL CASTING IN NEPAL

Nepalese images, ritual and domestic objects are either cast by pouring molten metal into a prepared mold or hammered out of sheet metal.

Casting is done by the “lost wax” (cire perdue) method, known in Newari as thajya.  In this process a wax model is encased in clay then melted out (“lost”) to be replaced by a molten metal.  After the metal hardens the clay mold is broken away revealing a metal replica of the wax model.  A solid wax model produces a solid casting; a hollow wax model with a clay core produces a hollow cast.  For reasons of economy and easy in handling, usually only small sculptures and objects are solid cast.  All cast pieces require hand finishing by various processes.  Wax models may be one of a kind or replicas.  Replicas are made by pressing a warm harder wax around an original model, of wax, metal, or other material.  When the hard wax is removed it becomes a mold into which soft wax is pressed to replicate the original.

 The technique of hammering sheet metal into relief is called embossing or repousse.  The latter is a French term loosely translated as “pushed again”, reference to the alternate front and back hammering the technique demands.  Newar craftsmen use the term tho- or thvajya, “hammering work”. Because of the unforgiving nature of the hard metal, in which, unlike casting, it is difficult to rectify mistakes, the practice of this difficult technique is relatively rare worldwide.  Nepal is an exception with a continuous tradition which is largely flourishing only in Nepal.  Repousse accounts for a wealth of sacred images, objects and architectural embellishment throughout Nepal.  Large hollow images of dovetailed sheet metal are often supplemented with solid cast hands and other details.

 Today much of the metal used by Nepalese craftsmen is imported but traditionally copper was readily available in Nepal and in ancient times was an important export.  Thus, older cast images tend to be of copper though conventionally they are referred to as “bronze”, a mixture of copper and tin.  The use of brass in casting is a recent phenomenon.  Because of its relative malleability, sheet copper is the metal of choice for repousse work, although brass, silver and gold are also used.  Typically, images whether cast or hammered are “fire gilt”.  From about the ninth century images were increasingly inlaid with precious and semi-precious stones.  The use of paint and “cold gold” (gold leaf applied without heat) is confined to work made by Tibetans or by Newars for the Tibet trade.