The technical revolution in production

The very large increase in the level of the production of cast iron which took place in the eighteenth century was made possible by the development of a method for smelting iron with coke.

By the second decade of the nineteenth century the production of basic pig iron in Britain (from which both wrought and cast iron were manufactured) was 400,000 tons (406,420 tonnes) per annum, as against about 23,000 tons (23,369 tonnes) a century earlier. That tremendous expansion in output forms a central theme in every account of the industrial revolution. The starting point was the discovery by Abraham Darby I in 1709 of a method for smelting iron with coke. If the industry had still been reliant on charcoal it could not have met the increased demand of the second half of the century. Coke-smelting provided increased capacity, especially once steam power was used for blowing, and it enabled cast iron to be produced more easily. After the 18th century innovations had taken hold, the smelting process underwent no further change until the 1830s, when the introduction of the hot blast process permitted uncoked coal to be used in furnaces and increased their efficiency yet more.

Industrial methods for manufacturing and shaping wrought iron were developed at the end of the eighteenth century.

Improved iron smelting was complemented from the 1780s by the transformation of the forging process in which pig iron was converted to workable wrought iron. The ironmaster Henry Cort took out two patents in 1783-4, one for a coal-fired reverberatory furnace and the other for a method of rolling the bloom of iron (as it was known) into standard shapes. Without the ability to roll wrought iron the structural advances which it eventually permitted would never have taken place.