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Introduction to the archaeometallurgy of iron
Donald B. Wagner

Bronson and Charoenwongsa’s summary of two descriptions of iron-smelting by the ‘Iron Kuay’ of Cambodia

3. Iron. mining and smelting, ca. 1880. Villages of the Kui, Cuoi, Khouy, etc. ethnic group, Phnom Deck mountain range, Kompong Soai Province, Kampuchea. Personally observed by J. Moura (1883: 43-6) and by E. Fuchs and E. Saladin (1882: 286–292; summarized at length by Beck (1891: 1009-11)).

Two kinds of ore are used, one called ‘heavy’ and the other ‘light.’ The latter is preferred because of the hardness of the iron produced, which makes it suitable for weapons manufacture. Moura seems to say that the ‘light’ ore is ‘very rich with a 65-66% metal content.’ Fuchs and Saladin cite a less impressive 35-40% metal content without mentioning that the Kui recognize two types of ore. The miners apparently do their own charcoal-making and smelting. The mines are in the Phnom Deck; smelting is done in the villages at the edge of the range.

Because of the expense, furnaces tend to be built by groups of villagers or even by several villages. Each is a long rectangle in plan, 0.9 m wide, 2.5 m long and about 0.4 m deep, made of clay mixed with white sand. The top of this shallow basin is open: its walls taper from 20 cm in thickness at the base to about 5 cm at the lip. The furnace proper rests on a solid stamped-clay pedestal that raises the bottom of the hearth 80 cm above ground level. Both ends of the furnace basin are pierced with holes for tapping slag. Each of the sides has 26 holes with 26 tuyères which project some distance into the furnace. All tuyères on each side are connected by bamboo tubes to a common bellows. There are thus two bellows in all. Each has the form of a drum made of stamped clay about 50 cm in diameter, with a leather diaphragm attached at its center to a cord and a spring pole. The feet of three operators (to each bellows) press the diaphragm down, forcing air into the furnace; the spring pole pulls the diaphragm back upward when the operators step off, letting the bellows refill with air. Two high bamboo screens protect the operators from the heat of the open hearth.

About 250 kg of ore and 5-6 hectoliters of charcoal, arranged in layers, constitute the charge. Once lit, the fire is blown gently al a rate of 8 strokes per minute for the first eight hours, then blown at a more vigorous pumping rate for four or so hours more. One heat is finished per day, yielding 10-15 kilograms of iron.

Items used as money by various peoples in Southeast Asia, according to Colquhoun (1885: 314). Item 1 is the iron bar mentioned in the text.

The bloom then is worked up into half-kilogram bars with pointed ends (illustrated in Colquhoun 1885: 314). This is done in a separate hearth, blown with a pair of upright single-acting piston bellows (Moura) or a single horizontal double-acting windbox bellows (Fuchs and Saladin). The iron bars contain ‘mixed particles’ of iron and steel but are otherwise of a high purity. They are highly prized by many peoples of the surrounding area. The bars are traded all over Cambodia, Annam and Siam. The Laos use them as money.

Comment: This is the best description of traditional smelting we possess from Southeast Asia. Interestingly, the process is one of the most unusual. The furnace, clearly described by both sources, is unique among recorded bloomeries. The closest analogue is found in the tatara furnace of Japan, which is also long, narrow and furnished with rows of tuyeres along both sides, although it is much larger and produces a different kind of iron. The Kui bellows is unique in Southeast Asia (nothing like them is reported in Marschall’s comprehensive 1968 survey) but is of a type common in Bihar and Orissa in eastern India, where clay drum bellows with spring poles and often with several operators per bellows were widely used by small- and medium-scale ironmakers of the preindustrial period.

The reason for the furnace design is not clear; one imagines that with a somewhat deeper basin and an excess of fuel, such a device might be able, like the tatara hearth, to produce a natural steel or even a mixture of steel and cast iron. The bellows is without question an import from India. The fact that the Kui were not in close contact with overseas areas at the time of Moura’s, Fuchs’ and Saladin’s visit suggests that the importation may have occurred at a relatively early date.

Copied directly from Bronson & Charoenwongsa 1986: 9–11. I have corrected some errors.

References

Beck, Ludwig. 1891. Die Geschichte des Eisens in technischer und kulturgeschichtlicher Beziehung. Erste Abteilung: Von der Ältesten Zeit bis um das Jahr 1500 n. Chr. Zweite Aufl. Braunschweig: Friedrich Vieweg und Sohn. ia802604.us.archive.org/21/items/diegeschichtede05beckgoog/diegeschichtede05beckgoog.pdf

Bronson, Bennet, and Pisit Charoenwongsa. 1986. Eyewitness accounts of the early mining and smelting of metals in mainland South East Asia. Bangkok: Thailand Academic Publishing.

Colquhoun, Archibald Ross. 1885. Amongst the Shans. New York: Scribner & Welford. ia800909.us.archive.org/4/items/amongstshans00colqrich/amongstshans00colqrich.pdf

Fuchs, Edmond, and M. E. Saladin. 1882. ‘Mémoire sur l’exploration des gites de combustibles et de quelques-uns des gites métallifères de l’Indo-Chine’. Annales des mines 8. série, tome 2.: 185–298. Summarized in German by Beck (1891: 1009–1011). patrimoine.mines-paristech.fr/items/viewer/211#page/Image+106/mode/1up

Moura, J. 1883. Le royaume de Cambodge, Tome premier. Paris: Leroux. ia802907.us.archive.org/15/items/leroyaumeducamb00mourgoog/leroyaumeducamb00mourgoog.pdf

Last edited by DBW 1 March 2023
Stylistic changes 30 May 2024