'Gartsherrie by Night' by CR Stanley, 1853. Oil on canvas. 'Gartsherrie by Night' by CR Stanley, 1853. Oil on canvas.

Hot Blast & Iron Burgh

5 min read

From 1830, a combination of technological advances and serendipity led to the Old Monkland area coming to international prominence as the ‘Iron Burgh’ with one of the greatest concentrations of blast furnaces for making iron in the world. The town of Coatbridge was born from this economic boom drawing in migrants from the Highlands, from Ireland, England and Wales. Soon the town rivalled its near neighbour, Airdrie in terms of size.

Iron Smelting

Iron had been smelted in the Highlands for centuries using charcoal from Scotland’s woodlands to fire the furnaces.  The increasing demand for fuel led to rapid deforestation and the growth of demand for coal as an alternative fuel. The first ironworks in Scotland to use coal as a fuel was the Carron Works near Falkirk which opened in 1759. The coal was first heated in a sealed furnace with no air supply to turn it into coal. Next the coke was put into a blast furnace with ironstone and limestone and heated to around 1,300 degrees Celsius. The molten iron would be ‘tapped’ from the bottom of the furnace and cast into long ingots called ‘pigs’.

For a long time after the opening of the Carron Ironworks the growth of the iron industry in Scotland remained slow. It was not until the 1780s that other coke-fired ironworks were established in Scotland with the opening of the Wilsontown and Omoa Iron Works, both in Lanarkshire and Scotland remained a net importer of iron, even for Scotland’s first iron boat. This slow growth didn’t really accelerate until the arrival of the ‘hot blast’ in the 1800s.

The Hot Blast

The trigger for this dramatic change was James Beaumont Neilson’s development of the Hot Blast process for making pig iron, which he patented in 1828. This innovation allowed local industrialists to take advantage of David Mushet’s earlier discovery that the local ‘splint coal’ (a seam of coal containing iron nodules, previously considered useless) could be used directly in a blast furnace to smelt iron without first turning the coal into coke.

The Iron Burgh

William Baird and Company founded their Gartsherrie Iron Works in 1830. They were a farming family who had made their fortune by mining coal on their lands. The Monklands were rich in the raw materials for making iron: ironstone, coal and limestone, as well as fireclay for making silica-rich bricks for lining the furnaces. By this time steam engine technology was well developed. Steam engines freed factories from needing water power so unlike the earlier ironworks it didn’t matter that Gartsherrie was not next to a river. The invention of the hot blast coincided with the development of the first public railways which linked the Monklands coalfields and ironworks with the canal network and with Glasgow and beyond.

 

Gartsherrie was the first purpose-built ironworks to use the hot-blast process. It began with a single furnace which was put into blast on 4 May 1830. By 1843 there were 16 furnaces ranged in two rows on either side of a branch of the Monkland Canal. Soon a host of other pig iron works followed: Summerlee, Langloan, Dundyvan and Carnbroe all joined Gartsherrie and the earlier Calder Iron Works around Coatbridge while a few miles south-east there were the Calderbank, Chapelhall and Coltness Iron Works.

 

 

 

 

An Ironworks and a Community

Soon other ironworks followed and Coatbridge expanded rapidly, drawing skilled and unskilled workers from the Highlands, from Ireland, England and Wales. Workers and their families were housed in single-storey, single room houses ranged in rows or around squares. Conditions were very poor, especially for the lowest-paid workers who had to share a water pump among many families and a shared outside toilet (the ‘privy’) that had no plumbing and was simply emptied into a pit. The houses were built right next to the works, often in the middle of nowhere and the workers were paid in tokens that had to be spent in the company’s own shop at inflated prices. This was the hated ‘Truck System’.

This photograph from 1910 gives an idea of the conditions Lanarkshire ironworkers lived in. This is Furnace Row, Wishaw. Off camera to the left a railway line runs right past the back of these houses.

This photograph from 1910 gives an idea of the conditions Lanarkshire ironworkers lived in. This is Furnace Row, Wishaw. Off camera to the left a railway line runs right past the back of these houses.

The development of the pig iron industry led to the growth of nearby malleable iron works, foundries and engineering works.

Cast Iron and Malleable Iron

Cast iron is the end product from a blast furnace. It is a hard iron that can be cast into decorative shapes or simple structures but is brittle so not ideal for building large engineering structures.

Cast iron can be refined by a process called ‘Puddling’ to produce malleable iron. This has fewer impurities and a fibrous structure which means that it can be shaped by hammering and rolling. Malleable iron, being less brittle could be used to build bridges, ships and railway lines.

 

 

Cast iron is the end product from a blast furnace. It is a hard but brittle iron that can be cast into decorative shapes or simple structures but is brittle so not ideal for building large engineering structures.

Cast iron can be refined by a process called ‘Puddling’ to produce malleable iron. This has fewer impurities and a fibrous structure which means that it can be shaped by hammering and rolling. Malleable iron, being less brittle could be used to build bridges, ships and railway lines.

The puddling process was invented in England in 1783 but wasn’t suited to Scottish pig iron. Scotland continued to import most of its malleable iron until improvements were made to the process in the 1830s. By 1837 the Dundyvan Iron Works in Coatbridge and the Monkland Steel and Iron Works in Calderbank were using puddling furnaces on a large scale. Others soon followed.

Iron Makes Way for Steel

Steel is very strong and new processes developed in the middle of the 19th century made it cheaper to produce than malleable iron. The output of a puddling furnace was limited by what the operative, known as a ‘puddler’ could physically lift but the new steelmaking processes didn’t need to be worked by hand so the furnaces could be much larger.

Experiments with large-scale steel production in Scotland began in 1871 and less than a decade later Colville’s recently-founded Dalzell Works in Motherwell moved over from making malleable iron to open hearth steelmaking, the start of a huge steelmaking empire.

End of the Iron Burgh

The southernmost of the Summerlee blast furnaces being brought down by gelignite in 1938

The southernmost of the Summerlee blast furnaces being brought down by gelignite in 1938

A slump in the price of iron in the 1920s caused most of the ironworks to close. By now most of the local ironworks were very outdated and with local supplies of ironstone exhausted and the railways replacing the canals for transport, their competitive advantage was gone. With steel replacing malleable iron manufacture, blast furnaces were now only needed to supply steel furnaces. It helped if the ironworks and steelworks were close together so Gartsherrie Ironworks survived as supplier of pig iron to Northburn Steelworks but most of the steelworks were centred on Motherwell, further south.

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