The gharua or the dhokra kumar tribes are the traditional metal workers of West Bengal. They are semi-nomadic and are related to the malhars of Bihar and the situlias of Odisha. They live in Bankura, Burdwan, Midnapore, and Purulia districts, all of which are close to the Chota Nagpur region of Bihar; the malhars live in the hills and forests. The dhokras of West Bengal, Bihar, and Odisha claim kinship with the dhokras of Madhya Pradesh. They are all part of the same tribal group of that area. Their metal ware has a strong and primitive folk style. They make small images of Goddess Lakshmi, her mount, the owl, Lord Lakshmi Narayan riding on an elephant, and Radha and Lord Krishna in different attitudes. These images are kept in the household shrines of newly married Hindu couples to bring prosperity and happiness. Decorative caskets were made and sold, as were measuring bowls that were considered as symbols of Goddess Lakshmi. Ritual lamps of different designs, small models of animals and birds, and a variety of trinkets and bells are also made.
The dhokras use the lost wax process to cast hollow brass objects and images. The object of wax is modelled in detail around a hardened clay core, which has approximately the same shape of the object to be cast. Layers of soft, refractory material are laid over the wax model and hardened into a mould. The wax between the core and the inner surface of the mould is lost or burnt out as the mould is heated and the molten metal takes its place and hardens between the core and the inner surface of the mould which holds a negative impression of the wax model in all its detail. The outer surface of the hardened metal reproduces the shape and details of the original wax model with the core producing the hollow interior. The hard core and the mould become soft and spongy on firing and are easily removed. The dhokra craftspersons have a wonderful sense of shape and surface decoration. All their products are embellished with fine linear decorations which conform to the general shape of the objects. Religious images — like Goddess Durga in her avatar of Mahishasuarmardini where she slays the bull headed demon, Mahishasura — are cast.
At Nabadwip, the old centre of Vaishnava culture some artisans families make small images of gods and goddesses, and decorative figures which are cast solid. Similar figures are made in the Chitpur and Bhawanipur areas of Calcutta. The technique used is a fine-oiled, sand casting method. The metals used are brass, copper, bronze, silver, and octo alloy (an alloy of eight metals — gold, silver, copper, tin, nickel, zinc, lead, and iron). The traditional metal workers of West Bengal who work with copper and its alloys are known as kangsakars or kansaris. One group originates from the karmarkars or blacksmiths and the other from the pasana branch of sutradhars, the carpenter and wood-carving caste. They make articles from kansa alloy, which is seven parts of copper and one part of tin and the shapes are made by beating and hammering. Kansaris and metal workers from different caste groups specialise in mould or die casting, using the hammering process; semi-tribal dhokras never use any process other than the lost wax process. Traditional metal ware is made by casting, forging, or shaping. The metals used are copper and its alloys. For lost wax casting and die casting, brass and bronze are generally used. An alloy of 70 per cent copper and 30 per cent zinc is considered to be the best brass.
Metal craftspersons working with brass are found in most districts of West Bengal with local variations. The kangsakars, bell-metal artisans make their wares from the kansa alloy. Ritual ware is made from copper sheets, eating utensils are made of kansa, and utensils for cooking are cast in brass or shaped in sheet brass, copper, or iron. The seven to one alloy used in Bengal does not tarnish and is resistant to mild acids, but it is not malleable enough for easy working. Kangsa artisans work in groups of five and plates, bowls or tumblers are forged from lumps of kansa on anvils and steel shapers in a cycle of heating and hammering. The lumps of metal take the desired shapes and are finished on indigenous, hand-operated lathes. Die cast utensils use three moulds — one for the core and two for the outer shape. Sheet metal utensils are made by beating the sheets to the required shape on anvils and shapers. Elaborate shapes are made by dovetailing the parts and welding them together by heating and hammering.
Surface decoration is rare in the utensils of West Bengal but very intricate workmanship is found in the repoussé ornamented pieces of Kansaripada of Bhawanipur in Calcutta. All the utensils have simple but well-balanced shapes suited to their purpose. The products made are beautifully shaped and decorated caskets, platters, cups, bowls, and other items in silver, brass, and copper. At Suri in Birbhum district, wooden bowls are embellished with sheet metal decorations, which are traditionally made in different sizes for different measures of rice were extensively used by rich farmers;
Each utensil centre has its own well-known design like the beautiful chakaibati of Tamluk, chamby ghati and phero of Kangra and the different designs of the kalshis of Vishnupur. The products are divided into five groups: thalas or plates; batis or bowls; gelas or tumblers; ghatis or drinking pots; and kalshis or pitchers for storing water. The kalshis or pitchers are shaped in three to four pieces and welded together in the indigenous method. Ghatis or drinking pots and tumblers are shaped in one piece. They are all traditional Vishnupur designs.
Adibasis, santhals, or mundaris of the Chota Nagpur hill areas of Bihar and the western districts of West Bengal never use cast metal utensils. They use a large beautifully proportioned heavy metal bowl known as jambati, a heavy and deep platter for eating and drinking purposes, earthen pots, and beaten brass and iron utensils for cooking, drinking, and water storage. Cast brass household utensils consist of cooking pots, bowls, storage pots, and a variety of interestingly shaped dishes and caskets for carrying and offering paan (areca nut and betel leaf combination).