The word Madhucchista means beeswax. It attains a wider significance in Hindu metallic iconography and iconometry as well as in iron-casting by what is known as the “lost-wax” process. The roots of this technique can be traced back to the Indus Valley Civilization or the Harappa Culture (3rd millennium BCE) and it is still used for casting bronze icons of gods and goddesses, particularly in South India.
In accordance with agamic prescriptions and mensuration, a craftsman prepares in beeswax a model of the image, complete with all its bodily components as well as weapons, if any.
After placing beeswax tubes of the length of a datura flower on the back, shoulders, neck, or crown of the image he smears it with a past of refined clay. This paste is applied three or four times all over the image. The first clay layer is thin and is dried in the shade.
A few days later, a second thick layer is applied leaving the mouths of the tubes open and so on.
The quality of metal required to make the image depends on whether the image is to be cast in bronze, brass, copper should be ten times that of the beeswax of silver twelve times and of gold sixteen times. The image is then encased with clay in the form of a mold.
To melt the wax, the mold is heated. Molten metal poured into the mouth of the tube in a continuous stream till it is filled to the brim. It is then allowed to cool naturally, and thereafter the mold is broken. The metal image or icon is an exact replica of the beeswax model in all its forms. The image is then given the finishing touches. Its installation in a temple is done after an elaborate ritual.
In general, the murti used for processions and other purposes are made of metal. In South India, they are generally made of bronze, and in North India, brass is also used.
The expertise of the craftsman is such that a devotee sees only divinity in the idol and not the metal of which it is made.
The features of the idol are so accurate and harmonious that it is only the divine form that stands out, subsuming the metallic matter.