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Metal crafts
Almost identical bronze carts discovered at Chanhu-daro and
Harappa, seem to indicate a common manufacturing origin.
Gold was almost certainly imported from the group of
settlements that sprang up in the vicinity of the goldfields of northern Karnataka,
because the composition indicates electrum (gold-silver compound, called soma) and copper
could have come principally from Rajasthan. Lead may have come from Rajasthan.
Quarters of the lower city in Mohenjodaro seem to have housed
artisans specializing in different crafts indicating the possibility of occupational
specialization among the fire- and metal-workers. Copper and bronze were used
for making tools and implements. These included flat oblong axes, chisels, knives, spears,
arrowheads , small saws, and razors. All these could be made by simple casting, chiseling,
and hammering.Four main varieties of metal have been found: crude copper lumps in the
state in which they left the smelting furnace; refined copper, containing trace elements
of arsenic and antimony; an alloy of copper with 2 to 5 percent of arsenic; and bronze
with a tin alloy, often of as much as 11 to 13 percent. The copper and bronze vessels of
the Harappans are among their finest products, formed by hammering sheets of metal.
Casting of copper and bronze was understood, and figurines of men and animals were made by
the cire-perdue (lost-wax) technique.
Other metals used were gold, silver, and lead. Lead was
employed occasionally for making small vases and such objects as plumb bobs. Silver is
relatively more common than gold, and more than a few vessels are known, generally in
forms similar to copper and bronze examples. Two examples of silver seals have been found.
Gold was generally reserved for such small objects as beads, pendants, and brooches.
Other crafts
Lapis lazuli was probably imported from Iran rather than
directly from the mines at Badakhshan. Turquoise probably came from Iran; fuchsite from
Karnataka; alabaster from Iran; amethyst from Maharashtra; and jade from Central Asia.
Other special crafts include the manufacture of faience
(earthenware decorated with coloured glazes)--for making beads, amulets, sealings, and
small vessels--and the working of stone for bead manufacture and for seals. The seals were
generally cut from steatite and were carved in intaglio or incised with a copper burin
(cutting tool). Beads were made from a variety of substances, but the carnelians are
particularly noteworthy. They include several varieties of etched carnelian and long
barrel beads made with extraordinary skill and accuracy. Shell and ivory were also worked
and were used for beads, inlays, combs, bracelets, and the like.
Ffragments of cotton textiles recovered at Mohenjodaro provide
the earliest evidence of a crop and industry for which India has long been famous.
Perhaps, raw cotton was brought in bales to the cities to be spun, woven, and perhaps
dyed, as the presence of dyers' vats would seem to indicate.
Neighbours
In the Metropolitan Museum of Art is the bronze sword of King
Adad-nirari I, a unique example from the palace of one of the early kings of the period
(14th-13th century BC) during which Assyria first began to play a prominent part in
Mesopotamian history.
The Persian bronze industry was also influenced by Mesopotamia.
Luristan, near the western border of Persia (Iran), is the source of many bronzes that
have been dated from 1500 to 500 BC and include chariot or harness fittings, rein rings,
elaborate horse bits, and various decorative rings, as well as weapons, personal
ornaments, different types of cult objects, and a number of household vessels.
A sword, found in the palace of Mallia and dated to the Middle
Minoan period (2000-1600 BC), is an example of the extraordinary skill of the Cretan
metalworker in casting bronze. The hilt of the sword is of gold-plated ivory and crystal.
A dagger blade found in the Lasithi plain, dating about 1800 BC (Metropolitan Museum of
Art), is the earliest known predecessor of ornamented dagger blades from Mycenae. It is
engraved with two spirited scenes: a fight between two bulls and a man spearing a boar.
Somewhat later (c. 1400 BC) are a series of splendid blades from mainland Greece, which
must be attributed to Cretan craftsmen, with ornament in relief, incised, or inlaid with
varicoloured metals, gold, silver, and niello. The most elaborate inlays--pictures of men
hunting lions and of cats hunting birds--are on daggers from the shaft graves of Mycenae,
Nilotic scenes showing Egyptian influence. The bronze was oxidized to a blackish-brown
tint; the gold inlays were hammered in and polished and the details then engraved on them.
The gold was in two colours, a deeper red being obtained by an admixture of copper; and
there was a sparing use of neillo.
Weapons and implements
1. Spear and lance heads and arrow heads.
These weapons occurred at all levels at Harappa, Lothal,
Kalibangan and Chanhudaro. Chanhudaro arrowheads are made from sheets of .02 to .05 in.
thickness and have backward projecting barbs. The Lothal arrowheads are thin and without a
barb.
2. Knives.
Knives occur in a variety of shapes: triangular with leaf-shaped blades
with curved ends, plain, narrow, straight; some have curved edges and some have
rectangular sections.
3. Swords and Dirks.
These have a pronounced mid-rib and thick tang with holes located at the
base of blade or on the tang itself.
4. Blade axes and celts.
Long, short, narrow, broad. Some are flat copper celts with a
lenticular cross-section, broken butt, slightly concave sides and sometimes concentric
working edge. A shouldered celt and a sleeved copper which is perhaps a precursor to the
anthropomorphic copper hoard were also found.
5. Socketed axes.
Mohenjodaro and Chanhudaro. The axe from Chanhudaro is made of bronze and
perhaps belongs to the Zhukar period.
6. Maces.
Pear-shaped copper maces.
7. Razors.
Of several shapes.
8. Chisels.
Of several shapes and in relatively large numbers. Sizes vary from short
to long, sections vary from rectangular, round to square. The edges are doubly sloped,
abrupt and occasionally displayed. Typical ones are with broad, rectacular sectioned tangs
and narrow blades.
9. Saws.
Bronze. With very regular, small teeth. Was proably fixed with a wooden
handle with 2 or 3 rivets placed wide apart. Circular saw was found at Lothal and was
perhaps used to cut grooves in cylindrical objects.
10. Sickle blade.
Infrequent occurrence.
11. Tubular drills.
Coghlan refers to these as the earliest examples in the world. The drills
are the tapered tubes of thin copper and bronze. The groove left between the core and the
wall varies in width indicating variance in the circumferences of the tools. A twisted
drill, the fore-runner of the modern drill was found at Lothal.
12. Fish hooks.
Made of sheet copper with an eye on the top and a barb at the pointed end.
A few unbarbed fish hooks have also been found. Metallic fish-hooks are the earliest
examples found anywhere in the world.
13. Others: awls and reamers, mid-ribbed
swords, mirror, gouges, net sinker, needles, crapers, daggers and shovel.
Techniques. Annealing entails heating
of cold worked brittle metal to regain its malleability. The Harappans seem to be
acquainted with this technique (See Chanhudaro wire TF-C48; ASI, No. 49 and Chanhudaro
Celt TF-C4-3; ASI No. 252 252988). Smelting (See furnace at Pl. VI, Figs. 33-35). Smelting
oxide and carbonate ores involved placing the ore in wood or charcoal fire over a
clay-lined pit. The metal regulus was kept and the slag portion thrown away. Melting of
native copper was done by putting the regulus over furnace or fire in a crucible and then
casting it. Smelting of sulphide ores to obtain refined copper involved the following
stages (Agrawala, op. cit., p. 157):
a. the ore was roasted to remove the
bulk of sulphur.
b. the roasted ore was smelted which
removed slag from copper matte (copper and iron).
c. the copper matte was roasted. This
process yielded blue material rich in copper and slag rich in copper and iron.
d. further roasting of blue material.
e. the roasted blue material was
smelted with charcoal which resulted in 3 gradients: 1. black copper; 2. rich copper
matte; 3. slag rich in copper.
f. the black copper was melted which
separated refined copper from slag rich in copper.
g. the pure copper thus obtained was
cast and used in making a variety of vessels, tools, implements and jewellery.
The native and oxide ores were in
common use as shown in Mohenjodaro and Rangpur artefacts. Use of sulphide ores is
suggested by Chanhudaro adze (TF-C4-1, ASI N.2593 P; M 43, Pl. LXIV, 10).
Casting. Open cast method used for
flat axes. Closed moulds were used for the heads of staves.
Cire Perdue or Lost Wax process (See
Pl. VI, Fig. 31). The toy cart, the figure of a dancing girl and fine toy animals and
birds found at Lothal and other sites indicate use of this method. Wax model is made on a
clay core. The thickness of the wax depends upon the thickness of the required metal. Then
a single outer mould of clay is bilt up with a sprue-cup. The whole unit is then heated up
so that wax melts and runs out. Core chaplets are inserted to prevent shift of clay.
Molten metal is poured into the cavity. Then the outer clay mould is broken. The object
which comes out with a rough surface is smoothed by polishing and rubbing down with horn.
Furnaces. Sixteen furnaces of three
shapes were found at Harappa. One of them was a pottery jar embedded into earth. The
technique is used even today by gold- and silver-smiths in India. Two other furnaces, one
3ft. 4 in. dia and cylindrical and the other 3ft. 5 in.dia. and pear-shaped are lined with
bricks with their walls having mud-plastered vitrified slags. A window allows the
placement of crucible with metal. The find of molten metal and thick terracotta bowl-like
crucible near a circular furnace at Lothal confirms that copper ingots were melted in it.
Another rectangular furnace was found in copper-smith's workshop at the same site. A few
furnaces were also found at Kalibangan.
Running on method of joining. The
parts to be joined are cleaned and molten bronze is poured over the parts to be joned. A
tanged sword was joined to its hilt by this method.
Soldering method involved the use of
an alloy which has a lower melting point. The soft solder is applied by a heated metal
rod. Sanahullah notes that Harappans could perform gold and silver soldering.
Rivetting method involved the
hammering down of simple metal rods at both ends to constitute a rivet. Rivet holes have
been noticed in knives, bracelets and lances.
Lapping was the method used to join
tubular handles to the vessel. Teal welding was also known to the Harappans.
Alloying. Ten, lead and arsenic were
alloyed with copper. The criteron of determining whether the alloying is deliberate is
accidental is the presence of more than one percent of tin. Out of 100 artefacts examined,
30 had tin content ranging from 8 to 12 percent. Arsenic alloying was used in 8 percent of
the artefacts. Nickle alloying was used in 4 percent of the artefacts and lead alloying in
six percent of the artefacts.
Higher percentage tin was used in
alloys used for bangles and pins.
Spear 2.27%; engraver 3.96%; mirror
5.47%; chisel 9.62%; bangle 11.82%; pin 13.83%.
The Harappans were metal forgers,
smiths and craftspersons capable of producing weapons, tools, instruments, pots, toys,
jewellery and decorative pieces of metal.
Electrum
Arthas'a_stra states: pure and impure
silver may be heated four times with copper sulphate, mixed with powdered bone
(asthituttha) again four times with an equal quantity of lead and again four times with
dry copper sulphate (sushkatuttha), again three times in skull and lastly twice in cow
dung. (Stanza 88). The use of the skull which is calcium phosphate is a cupellation
process for purification of silver. Galena was first smelted to crude lead and silver
concentrated by a process called Pattinson Process. The proess is based on the fact that i
fused argentiferous lead is cooled, a point is reached when nearly pure lead separates in
crystals. If crystals of lead were withdrawn by perforated ladles the remaining liquid
alloy would become increasingly rich in silver. About 7/8ths of the original lead is
removed by this process and the rest of the lead is reoved by cupellation process.
Separation of silver and other impurities from gold (electrum) was invented before Amarna
age, possibly during or shortly after Ur III period (ca. 2200-2000 B.C.)
Sources:
D.P. Agrawal, The copper and bronze
age in India, pp. 191,239;
Marshall, MIC, Pl. CXXXV and CXXXVI;
Vol. II-III, 501-2, Pl. CXXXVI, Pl. CXXXV; Pl. CXXXVIII, 6-7; Pl. CXXXVIII, 4,8; Pl.
CXLIII, 24-25; Pl. CXLII, No.14; CXLIII, 31,33,37; Pl. CXLII, 20-21, 36
M.S.Vats, Excavations at Harappa, VOl.
I-II, 387-88, Pl. CXXV, 15-18 and 22-64; Pl. CXXV, 52, 62-64; Pl. CXXXIV, No.29; Pl. CXXV,
38 and 58.
E.Mackay, FEM, Vol. 1-2, Pl. XXI, 105;
Pl. CXIX; Pl. CXIII,3; Pl. CXIII,2; Pl. CXXI, 25 to 32 aqnd 36, Pl. CXVIII, No.7; Pl.
CXXV, No.39, CXIX, No.1; Pl. CXIV, No. 235; Pl. CXIV, 6; Pl. CXIII, No.3
E.Mackay, 'Arts and Crafts of
Mohenjodaro', Art and Letters, No. XIII, p. 18.
S.R.Rao, Lothal and the Indus
Civilization, 1972, p. 28; fig. 20, no. 21; p. 84
E.Mackay, Chanhudaro Excavations, Pls.
LXXII, 11; LXIII,16; LXXX, 21-25; LXXVI, 8, 25-27; Pl. LXXII, 25 and LXXVI, 137; Pl.
LXXIII, No.32; Pl. XXXIII, No.31; Pl. LXII, 7; LXXX,9; lXXXI, 15; Pl. LXXX; Pls. LXVIII,
13,15; LXXV, 9; LXXVI, 38; Pl. LXXIV, 13.
S.R.Rao, Ancient India, Nos. 18-19,
No. 663, p. 30, fig.417, Pl. XXXVa, 3 and 4; fig. 442, p. 150;
Coghlan in C.Singer, History of
Technology, Vol. I
IAR, 1956-57, Pl. XVI.