Earlier days, the product of metal art was controlled by the government of the respected region. The secrets of fine metal work were restricted to only few and it was guarded from the outside world. The secrets of 2,500 years are passed from generation to generation. Even today Newari artisans can be seen working on metal crafts in the region of Tibet, Himachal Pradesh and Nepal. There methods are still remains unchanged for centuries.
Depending on the idol to be made, sketch is drawn on a sheet of paper, to mark all the proportion of the Buddha. Rough proportion are drawn on the 4 by 4 feet copper sheet. Depending on the idol to be made, copper sheet of 18 to 24 mm thickness is chosen. With the help of wooden scale which is specifically made depending on the length and width of the idol to be made, final proportion of the idol is drawn. A grid consisting of horizontal and vertical lines are created containing numerical representations. This grid helps in marking the measurement and to arrange the posture of figure within the given parameters. Using these grids, different variations in posture, placements of parts like hands and arms or the direction of head are made. Grid system helps in depicting the features of deity like complexity of multiple heads, arms and legs. Outline of the drawn proportion is hammered, different types of chisel are used under this process.
Cold chisel and hot chisel are two categories used in metal work. Cold chisels are made from tempered steel that are used for cutting metal which is not heated. Cold chisel is mainly used to remove excess or unwanted material but does not give smooth finish. Hot chisel is used to cut heated and soften the metal. Once the excess material is removed, hammering process is continued by placing the sheet on a tool called steel rod, which helps in embossing of sheet into desired shape. Different parts of the statue are made separately, which helps is detailing process. Due to the soft nature of copper, it is ideal to make metal figurine. It consumes less time while making idols compare to brass and also cheaper compare to brass, gold and silver. Meanwhile a mixture of pine tree resin and mustard oil is boiled for 30 minutes to form a thick paste with very high viscosity and red oxide is added for coloring purpose. Shaped metal sheet is placed over the paste. Due to the friction of the paste, metal sheet sits firmly on it. Fine details like jewelry and facial details are made with the paste as a base.
A mixture of Brass, Silver and Zinc is made in a ratio of 65:35:5. The mixture is used in the form of small balls or cylindrical shape while soldering process for joining the different body parts. This mixture melts faster than copper and has lower melting point compare to copper. Idol is sanded with sand paper to level the uneven surface. Gold is applied to the best and expensive metal sculpture. Generally there are mainly two method of applying gold the sculpture, gold-gilding and gold-plating. In gold-gilding, pure gold is mixed with mercury and heated to make thick paste and applied on the sculpture and allowed to set. It is heated using normal flame torch and mercury evaporates due to heat leaving just the gold on the surface. For gold-plating, thin layer of gold (also known as varak) is smashed in a glass container and applied on the heated metal sculpture. Due to the heat, gold spreads on the surface of the sculpture, this method requires gold in large quantity. Thus gold gilding technique is used on copper as copper reacts best with gold. Gold gilded sculpture is dipped in a solution made of traditional herbal plants (trade secret). This helps the sculpture attain higher shine and luster. Sculpture is painted with natural color and embellished with pearls and gems. The body of Buddha is given glossy finish and face is given matte finish. Fine details of face can be easily seen on matte finish. Painting of the idol is done by thangka painter. Generally it takes about 45 to 50 days to complete a 6 inch tall idol when done by a single craftsmen.