History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c15.s7: Northern Black Polished Ware
History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c15.s7
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Northern Black Polished Ware
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The Northern Black Polished Ware (NBP) is perhaps the finest of the Indian ceramic wares of the ancient period (Krishna Deva and Wheeler, pp. 55-59).It is a most distinctive pottery which displays a high degree of technological excellence. As the very name signifies, it is essentially a pottery of northern India but has a very wide distribution in terms of space. It is found almost all over of north India, having its focus in the ancient Magadha region of Bihar, that is the area around modern Patna. It is found in Bengal and also in Central India but rather rarely in Gujarat and Maharashtra. A few specimens have also turned up as far south as Amaravati near Guntur in Andhra Pradesh. Outside India it occurs in the present day Pakistan and even beyond in eastern Afghanistan. In terms of time it can be assigned to a period from 600-200 B.C., broadly but the recent C-14 dates place the beginning of this ware slightly later in 4th century B.C.
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Although the bulk of the pottery is black, that is having a black slip, we come across specimens of different colours ranging from steel grey to bluish black and even red and silver and golden NBP has also been reported. Sometimes reddish blotches are seen on vessels. Painted NBP has been reported at Sravasti. The pottery is made of extremely fine clay and the core is usually grey. It is treated with a thin slip which bears extremely high, almost mirrorlike polish. It is represented mostly by bowls with straight sides and dishes with incurred rim and the ware is thus akin to the PGW in form and fabric. It is, therefore, not unlikely that it may perhaps represent the further stage of technological development of the PGW. Besides, there are lids with flat terminals and carinated handles. The mirror-like polish of the NBP has proved to be extremely enigmatic and has so far eluded all attempts at solving the mystery. Several scientists have offered their own explanation based on their experiments, but there does not seem to be any general agreement within sight.
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Among the early attempts to explain the technology of the NBP, the noteworthy is that by Sana Ullah. His analysis revealed that “the slip on the pottern contains about 13% ferrous oxide which is responsible for the black colour. The original slip was evidently a highly ferruginous (possibly consisting of a finely levigated mixture of clay and red ochre) ground in water and applied to the surface of the vessel before firing.
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The black colour was doubtless developed by the action of reducing gases formed in the kiln. The polishing might have been done before or after the firing. The coating is not a siliceous glaze (Sana Ullah, p.58).
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Yet another authority has suggested that the pottery was fired at a very high temperature in saggars, as was done in the case of the PGW. This is very likely in view of the similarity in fabric of both the PGW and the NBP (Rowson).
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Bimson, an expert of the British Museum, has also explained the technology of the ceramic. In his option, cited by sir Mortimer Wheeler, “The unfired pots were dipped in a suspension of ferruginous inorganic material, probably resembling red earth and that after firing to a temperature of 800° the kiln was sealed so that the pots cooled in a reducing atmosphere. The mineralogical identity of the “red earth” has not been discovered and the main problem, namely the precise nature of the surface layer, still remained unsolved (Wheeler, 1959, p. 30).
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According to K.T.M. Hedge, the mirror-like polish of the NBP ware “was produced by an application of liquid clay, quite similar to that employed for manufacturing the body of ware, but which in addition to levigation was carefully further shifted and cleaned for the purpose of reducing heavier particles like felspar, quartz and limestone present in the clay by means of suspending and stirring the clay in water. This clear clay liquid was then peptized by the addition of an alkali containing material” (Hedge, 1962, pp.159-161; 1966, p.623). The clay solution thus prepared and treated with a little alkali gives a black shiny slip when fired in reducing conditions.
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The Alkaline material used by the NBP potters, according to Hedge, was sājji māṭṭi. He produced the NBP in his laboratory using ground red ochre and sājji māṭṭi in clay (Hedge, 1975, 188). H.C. Bharadwaj, on the basis of his experiments, observes that “We may tentatively suggest that the black colour of the slip is materially on account of carbon and our experiments and observations do not substantiate the presence of magnetite or ferrous silicate.” (in Sinha, p.19)
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Although there does not seem to be any general opinion about the technology of the NBP, K.T.M. Hegde’s observations are significant. He observes: “It appears that the potters were experimenting. They first used red ochre as the painting medium to decorate the Painted Grey Ware. In the second stage they ground it with clay and *Sājji māṭṭi* to produce the black slip on the Black Slipped Ware. In the third stage, they ground it with clay and *sājji māṭṭi* to produce the lustrous slip-glaze on the Northern Black Polished Ware. All the there wares were baked in a reducing atmosphere. The NBP was their highest achievement (Bharadwaj, 1975, p.190).