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Introduction to the archaeometallurgy of iron
Donald B. Wagner

The economics of direct and indirect iron production

Iron ores, and the fuel to smelt them, are available almost everywhere in the world in quantities which are adequate for pre-modern production levels. An important implication of this fact is that competition is intense and profits therefore low. This again means that iron production has commonly – with some interesting exceptions – taken place in poor regions whose natural endowments do not provide more profitable economic opportunities for their labour.

Swedish furnaces, 18th century

A family ironworks in Dalecarlia, Central Sweden, early 18th century; drawing by Lars Schultze (1701–1765) in a manuscript of 1732 now in the Royal Library, Stockholm. Reproduced here from the 1845 repr. of Schultze (1732, pl. 3). The man is charging the furnace, the woman is working the bellows (with her feet, while spinning yarn with her hands), and the boy is cleaving a hot iron bloom with an axe.

Swedish blast-furnace ironworks, ca. 1800 (from Garney 1816, title page).

In Europe, in these poor regions, direct smelting has clearly been the best choice of production method. Small-scale ironworks, operating in the slack periods of agriculture, could produce a few hundred kg of iron per year for sale in local markets to the blacksmiths of nearby villages. An interesting example is the family ironworks shown here, one of many in Sweden about 1732. Their bloomery is larger than those that are known archaeologically from earlier periods, and the family produced perhaps a ton of iron per year for their own use and for sale at local markets.

A fact which may come as a surprise is that, at the same time that Swedish families like this one were producing iron by the inefficient bloomery method, there were numerous blast-furnace ironworks operating nearby. One of these is shown here. As near as 50 km away, these works produced tons of wrought iron per day by a process that was vastly more efficient in ore, fuel, and labour. How could the small inefficient family ironworks sustain their production in the face of this competition? This was possible because the opportunity cost of their labour, outside the busy periods of the agricultural year, was very low. There was very little else that they could produce and sell, but they did have ore and fuel and an intimate knowledge of bloomery smelting, handed down through generations.

Comparative advantage


The traditional iron industry in Guangdong


This phenomenon of large- and small-scale ironworks close together, serving different needs within the same region, is a matter of comparative advantage. It can also be seen in northern Guangdong in the Ming and early Qing periods. Large blast-furnace ironworks produced cast iron which was shipped on the great rivers of the province to Foshan 佛山 for further processing. At the same time, very small blast-furnace ironworks throughout the province produced iron for local markets. One of the fundamental facts about blast-furnace iron production is that it gives great economies of scale: the larger the production, the lower the cost of the product. The smaller works were no doubt much less efficient than the larger works, but here again the opportunity cost of labour in the small works was low enough to make their production competitive against the larger works.

An important point here is that ‘progress’ is not a simple concept, and is intimately tied up with economics. A technique (in this case bloomery smelting) may be the right way to do things even when a more advanced technique (blast furnace smelting) is well known and is more efficient and therefore more ‘progressive’. (This point is complicated by another factor: the products of the earliest blast furnaces were often considered to be inferior to bloomery iron. This assumption may or may not have been correct.)

Furthermore, an economically important new development may be ‘regressive’. The small blast furnaces of Guangdong, mentioned above, were less efficient than the larger ones in the same province, but they were not primitive. This small type of furnace appears to be a sophisticated later development from the larger type (known since the Warring States period or earlier) rather than the other way around. A comparable development can be seen in colonial North America. With a small and thinly-spread population in the 18th century, there was not, in many places, an economic basis for the blast-furnace process with its requirement of continuous operation and large-scale production. The ironmasters chose instead to produce iron in bloomeries, but with the help of advanced scientific knowledge they developed the technique to a new level of sophistication. The story is told by Robert B. Gordon (1996; see also Gordon & Killick 1993).


Garney, Joh. Carl (1816). Garney’s handledning uti svenska masmästeriet, omarbetad af Carl Johan Lidbeck. 2 vols, Stockholm: Fr. Cederborgh. In Swedish. Vol. 1.

Gordon, R. B. 1996. American iron 1607–1900.  (Johns Hopkins studies in the history of technology). Baltimore and London: Johns Hopkins University Press. 

Gordon, Robert B., and David J. Killick. 1993. ‘Adaptation of Technology to Culture and Environment: Bloomery Iron Smelting in America and Africa’. Technology and Culture 34.2: 243–270.

Last edited by DBW 25 February 2023