History of the Iron and Steel Industry in Scotland

In Relation to Clydebridge and Clyde Iron

Early Iron Age

Celtic invaders introduced iron making to Britain about 800 BC. Some of the earliest traces in Scotland are from a group of Celtic invaders who reached the Firth of Tay and the Moray Firth around 250 BC, and then Inverness, Argyll and Galloway. They produced iron in small, clay lined bowl furnaces a foot or two wide by half a foot or so deep.
The Romans, who reached Scotland about 80AD also helped spread and develop iron making, but production was still relatively small.

Iron - 1600s to 1800

Iron has been made in slightly larger quantities in Scotland, since at least 1607 when Sir George Hay (later Lord High Chancellor of Scotland and Earl of Kinnoull), the first great ironmaster, began to produce iron near Letterewe on Loch Maree in Ross-shire. This used imported red haematite ores from Cumberland and Lancashire and may have commenced at Fasagh as an extension of an older ironworks. The remains of a furnace existed on the North shore of Lochmaree until about 1900 but have since disappeared. The remains still standing are of the Red Smiddy furnace, east of Poolewe, which was originally about 16 feet high. The site for these ironworks was chosen for the ready supply of coppice wood for charcoal and operated for at least 60 years, when exhaustion of local fuel supplies may have shut the works. Four other blast furnaces, exploiting imported ore and local charcoal, were sited at Invergarry (1727), Abernethy (1728), Glenkinglass, on the shore of Loch Etive (1727) and Nether Wellwood, Muirkirk, Ayrshire (1730). However, none of these furnaces survived after 1737, one cause being the inferior quality of the iron produced.

The first large blast furnace in Scotland was the Lorne furnace at Bonawe, near Oban, erected in 1750 to make use of local charcoal with iron ore shipped in from Ulverston (Furness). This was erected by the ironmasters of Newland furnace in Lancashire. Bonawe and operated for about 150 years. Goatfield furnace on Loch Fyne in Argyleshire was built in 1775 by the ironmasters of Dudden furnace in Cumberland and was supplied with Lancashire ore. But the nucleus from which the Scottish iron industry developed was Carron Iron Works in Stirlingshire. It was established in 1759, by John Roebuck, of Birmingham, a medical doctor involved in chemical and metallurgical research, and Samual Garbett a business man from Birmingham, with branch establishments in Edinburgh, in association with William Cadell of Cadell and Edington, ironmasters of Crammond. Carron was planned on a large scale for the times and produced 1500 tons of iron in its first year. The works produced armaments, grates, stoves, pots and pans.

The Carron Ironworks site was chosen as it had a convenient supply of water for driving the machinery. The blast was created, and the tilt-hammers, lathes, and other machines were driven by water applied over a large number of wheels. As the premises were extended the supply of water became inadequate. While James Watt was working out his improvements on the steam-engine, he entered into partnership with Dr Roebuck of the Carron Ironworks, and a joint-patent was taken out for a condenser. This partnership was not a fortunate one for Watt. During the time he was associated with Dr Roebuck, however, he erected a large steam-engine at Carron. It was not used to power the machinery directly but pumped water back into a reservoir that had passed over the waterwheels, to enable it to be reused. The engine was fitted with four pumps, which raised forty tons of water per minute to a height of thirty-six feet. It was also at Carron where cast-iron blowing cylinders, built by John Smeaton, were first introduced, in 1768.

On Sunday 26 August 1787, Robert Burns, just starting on a tour of the highlands, called to visit Carron Iron Works but, as the working practices were kept secret from the outside world, the porter at the gate would not let him in. He used a diamond to write on a window of the inn at Carron:

We cam na here to view your warks,
In hopes to be mair wise,
But only, lest we gang to hell,
It may be nae surprise:
But when we tirl'd at your door
Your porter dought na hear us;
Sae may, shou'd we to Hell's yetts come,
Your billy Satan sair us!

Carron flourished from the demand for munitions for the French and American wars, and in 1786 Edington and Cadel, in association with Carron, built Clyde Iron Works, on the north bank of the river Clyde, a few miles south east of Glasgow, primarily to relieve the pressure on Carron for armaments. These works were reputed to be the best in their day. During the Napoleonic Wars the famous short-barrelled naval guns known as 'carronades' were made there. Other large ironworks constructed in Scotland about this time were at Muirkirk in 1789, and at Calder in1793.

Clyde Iron Works began with two blast furnaces and a foundry, employing about 100 men. It was built on the land of Bogleshole, on an ancient burying place. When digging for foundations various urns were discovered containing ashes mixed with human bones on some of which were the traces of fire. The area before the development was agricultural and sparsely populated. Flax was grown and spun, and woven into linen.

In common with much of the Central Scotland area, there were deposits of coal and iron ore around Cambuslang. A Dr Meek estimated that about 100 coal pits had been wrought out earlier than 1790, and in 1787 a steam engine was erected to keep the village pit clear of water. The annual output of coal in the area then was about 30,000 tons.

Clyde Iron remained owned by the Caddells of Carron until 1810, when it was purchased by Colin Dunlop, who at the time was working the coals in the district of Carmyle. During the ownership of the Caddells, for a time, the Manager of Clyde Iron was James Outram, whose son George came to be founder, editor and proprietor of the Glasgow Herald.

In the days before gas was used for lighting (the streets of Glasgow were not lit until 1820) the blaze from the Clyde Iron Works furnaces, when in full operation, illuminated the district for miles around, as described by the Bridgeton poet Alexander Rodger:

The moon does fu well when the moon's in the lift;
But oh! the loose limmer takes mony a shift;
Whiles here, and whiles there, and whiles under a hap-
But yours is the steady light, Colin D'lap.

Na, man! Like true friendship, the mirkier the night,
The mair you let oot your vast columns o' licht,
When sackcloth and sadness the heavens enwrap,
Tis then you're maist kind to us, Colin D'lap.

Iron Industry Growth from 1828

It was to Clyde Iron that David Mushet came, at the age of 19 in 1791, as a clerk in the Accounts Branch. He became interested in metallurgy and was allowed to carry out experiments in his spare time. He later moved to the Calder Iron Works, then to Derbyshire, and in 1810 to Coleford in the Forest of Dean. David Mushet was the father of Robert Foster Mushet, an even more famous metallurgist who improved the Bessemer process and went on to develop tool steels, wear resistant rails and other steel alloys.

David Mushet contributed many valuable papers on the nature of metals and also discovered the native Black Band ironstone in North Lanarkshire, Ayrshire and Stirlingshire that later helped lead to the meteoric rise in the Scottish Iron industry, particularly in the Coatbridge area. This was primarily lead by the invention of the hot blast process at Clyde Iron Works , in 1828, by the Glasgow Engineer, James Beaumont Neilson, which transformed the cost of iron production.

From the memoranda of Colin Dunlop the actual make of pig-iron in 1811 at Clyde Iron was 2,447 tons, with 10 tons 18 cwts of coal used per ton of pig-iron produced, and the cost per ton of pig-iron was £8. By 1828 they made 5,884 tons of pig-iron with a coal consumption per ton of pig iron of 8 tons 2 cwt 2 qrs and a cost of pig-iron of £4 12s 1d per ton. In 1832, when the hot blast was in full operation, heating the air to 600 to 700 degrees Farenheight, the production had risen to 11,924 tons, the coal consumption reduced to 2 tons 12 cwts and the cost per ton od pig-iron £2 12s 8d. From 1834 onwards, the cost of heating the air itself gradually decreased, until in 1844 the fuel used for that purpose per ton of pig-iron cost only 9½d. A further breakdown of costs for that year for one ton of pig-iron at 34s 1¾d per ton was:

Coal, 2 tons ½ cwt at 4s 8½d......................................9s 6 5/8 d
Ironstone, 2 tons 18cwt at 6s 0 5/8d...........................17s 6 7/8d
Limestone, 6 ½ cwt at 6s 1 7/16d.................................1s 11 2/8d
Sub Total...................................................................29s 0 6/8d
Wages.........................................................................2s 0 1/8d
Sundries (charges ?).....................................................0s 7 5/8d
Repairs (about a third of the usual amount)....................0s 3 1/8d
Heating Air...................................................................0s 9 4/8d
Horses and Carts (removing slag)..................................1s 4 5/8d
TOTAL......................................................................34s 1 3/4d

The presence of blackband ironstone lead to the expansion of iron production in Monklands and Coatbridge. This was an area rich in coal and serviced by the Monklands canal since 1794. Iron works had been set up by a group of Glasgow ironmasters, Aitken, Dick, Fleming and McGregor at Calderbank, in 1797, to supply a growing demand (including, in 1819, the iron plates for the Vulcan, the first iron hulled passenger boat made in Scotland).

English iron works were slow to adopt the untried hot blast process, but at Dixons Wilsontown Iron Works it was discovered that the local hard 'splint' coal could be used direct in the furnace without previous coking; the first successful use of coal direct in blast furnace practice. From 1830 onwards, the combination of black-band ore, splint coal and Neilson's hot blast brought about very rapid progress. Between 1830 and 1847 Scottish iron production increased from 37,500 tons a year to 540,000 tons a year, providing the leading 27% of British iron production.

The demand for iron and the savings to be made using the hot blast resulted in infringements of J B Neilson's patent for the process. For example, local farmers, the Bairds, had made a fortune from coal mining and were investing this fortune in iron works. They had two coal pits at Gartsherrie and built blast furnaces there in 1830 using the hot blast process without a licence. Neilson sued successfully for £160,000, a sum that Baird easily afforded from the huge profits being made. By 1868 the Bairds owned 4 ironworks, plus many coal and ironstone mines. Gartsherrie was the largest ironworks in Scotland (and the second largest in Britain), followed by Summerlee Ironworks. Gartsherrie survived until 1967, and might have survived longer but it missed an opportunity to link the ironworks with the adjacent Northburn steelworks and become one of the first integrated steelworks (such as Clydebridge/Clyde Iron became).

A description of Coatbridge is given in a book on the industries of Scotland by Bremner in 1869:

"Though Coatbridge is a most interesting seat of industry, it is anything but beautiful. Dense clouds of smoke roll over it incessantly, and impart to all the buildings a peculiarly dingy aspect. A coat of black dust overlies everything, and in a few hours the visitor finds his complexion considerably deteriorated by the flakes of soot which fill the air, and settle on his face. To appreciate Coatbridge, it must be visited at night, when it presents a most extraordinary and when seen for the first time startling spectacle. From the steeple of the parish church, which stands on a considerable eminence, the flames of no fewer than fifty blast furnaces may be seen. In the daytime these flames are pale and unimpressive; but when night comes on, they appear to burn more fiercely, and gradually there is developed in the sky a lurid glow similar to that which hangs over a city when a great conflagration is in progress. For half-a-mile round each group of furnaces, the country is as well illumined as during full moon, and the good folks of Coatbridge have their streets lighted without tax or trouble. There is something grand in even a distant view of the furnaces but the effect is much enhanced when they are approached to within a hundred yards or so. The flames then have a positively fascinating effect. No production of the pyrotechnist can match their wild gyrations. Their form is ever changing, and the variety of their movements is endless. Now they shoot far upward, and breaking short off, expire among the smoke; again spreading outward, they curl over the lips of the furnace, and dart through the doorways, as if determined to annihilate the bounds within which they are confined; then they sink low into the crater, and come forth with renewed strength in the shape of great tongues of fire, which sway backward and forward, as if seeking with a fierce eagerness something to devour".

J. B. Neilson opened an iron works at Mossend, in Bellshill, in 1839, which became one of the largest producers of malleable iron. A Siemens open hearth steel melting shop was started at Mossend in 1880, but a strike in 1889, lasting nearly 15 months shut the works. The works were taken over by William Beardmore & Co in 1906 and production peaked during WW1 when 3000 people were employed.

Other ironworks were located in the Wishaw area. The Coltness Ironworks, opened in 1841 had 6 blast furnaces. It later added 2 open hearth furnaces for producing steel castings. The Wishaw Ironworks, opened in 1859 with 3 blast furnaces using ironstone from a pit on the other side of Wishaw main street. It closed in 1861 to be taken over by the Glasgow Iron Company, from St Rollox, who also operated a malleable iron works in Milton Street, Motherwell. The Wishaw ironstone was poorer quality and was exhausted by the 1870's, after which ironstone was sourced from Carluke and from Liberton and Lasswade, near Edinburgh.

The iron industry peaked by about 1871, at which time it employed nearly 40% of the Scottish workforce, and 25% of its' steam power. In Coatbridge the ground vibrated from the pounding of steam hammers and a forest of chimneys spewed soot and grit across Coatbridge, which had become the most polluted town in the UK, if not the World. At times it turned day into a night, lit by the blast from the furnaces.

The growth of the iron industry put demands on the coal industry. A Commission on coal in the UK in 1871 - made the following point about ironworks consumption of coal in Scotland.

"The following statement is necesary to enable the public to judge of the injury, in one point of light, done to the coal owners by the erection of ironworks. There are two blastfurnaces at Muirkirk, two at Cleland, three at Carmile or Clyde ironworks, in all seven, of which there are five at present in blast. Each blast furnace, blown by a steam engine, consumes, including engine coals, workmen's coals, and coals for calcining the mine or ironstone, at least 9,000 tons of coal annually: thus five blast furnaces will consume 45,000 tons. And as on an average each collier in Scotland does not turn out above eight tons of coal weekly, it will require 112 colliers to work the above quantity of coal, exclusive of other colliers and miners employed to sink pits, drive mines, and work the ironstone and limestone for the furnace. For these purposes it cannot take less than 150 additional hands; so that five blast furnaces will require 262 colliers and miners, formerly employed in preparing collieries for work, or in working coals for the domestic consumption of the inhabitants of Scotland. This evil is only beginning to be felt; it being certain, from the present high price and great demand for cast iron, as well as from the peculiar advantages attending many situations in Scotland, that twenty additional blast furnaces will be erected in Scotland within the space of ten years from present date, requiring a supply of 2,048 colliers and miners. This supply of hands must either be drawn from the collieries now working coal for the consumption of the inhabitants of Scotland, in which case coal will increase in price above any calculation now possible to be made ; or, erectors of ironworks must be compelled to breed hands for their works, by being prohibited by Act of Parliament, by a bill to be brought in for the special purpose, from employing any colliers now employed at the collieries".

By 1878 Scottish iron production had fallen to 14.5% of British output, partly owing to a prolonged strike of shipwrights, but also to competition from the Middlesborough and Cleveland areas which were using lower cost haematite pig iron. From 1885 the local ironstone and coal supplies were largely exhausted, with coal being sourced further south, and iron ore being imported from Spain, and from 1900 from Sweden. At this time steel was replacing iron and trade was shifting from the iron town of Coatbridge to the 'Steelopolis' of Motherwell.

The Calderbank ironworks, which had developed in size to 6 blast furnaces and 60 puddling furnaces, with a reversing mill producing malleable iron boiler and ships' plates, was one of those that failed to meet the new market for steel, and it closed in 1887 (the year that Clydebridge started) and was demolished. However, in 1890 a steelworks with 5 Siemens Open Hearth furnaces was built on the site. This was not successful, but the business was taken over in 1897 by James Dunlop & Co, owners of Clyde Iron Works, and work picked up. A steam turbine driven, 3-high plate mill was installed in 1910 but with the depression in the 1920s the works were closed for periods. In 1930 there was a severe slump in shipbuilding and Dunlops was taken over by the Colvilles, at which time the works was finally shut, although Colvilles moved the plate mill to Motherwell.

Lanarkshire Iron Works No of Blast Furnaces
Iron Works Location Started Closed 1830 1839 1843 1848 1869 1880 1901 1951
Wilsontown Carnwath 1779 1842 2 2 - - - - - -
Clyde Cambuslang 1786 1978 4 4 6 7 6 5 5 3*
Omoa Shotts 1789 1868 2 2 2 4 - - - -
Calder Monklands 1800 1921 4 6 8 8 8 6 6 -
Shotts Shotts 1801 1947 1 3 4 4 7 5 6 -
Chapelhall Bothwell 1825 1886 2 3 3 3 3 3 - -
Gartsherrie Monklands 1828 1967 1 8 16 16 16 14 12 5
Dundyvan Monklands 1833 1868 - 5 9 9 - - - -
Calderbank Monklands 1835 1887 - 2 2 6 6 6 - -
Summerlee Monklands 1836 1930 - 4 6 6 8 8 7 -
Coltness Wishaw 1837 1927 - 2 4 6 12 12 9 -
Carnbroe Bothwell 1838 1921 - 2 6 6 6 6 5 -
Castlehill Carluke 1838 1884 - 2 2 3 3 3 - -
Langloan Monklands 1841 1919 - - 3 6 8 7 5 -
Wishaw Wishaw 1858 1930 - - - - 3 3 4 -
Quarter Hamilton 1865 1887 - - - - 4 5 - -
TOTAL 16 45 71 84 90 83 59 8

*Note: by 1951 the three furnaces at Clyde Iron Works could produce 600,000 tons per year, equal to the total output of all 83 Lanarkshire furnaces in 1880.

Malleable Iron Works & Puddled Steel

Although cast iron is strong in compression, it is structurally weak in tension. Prior to the introduction of steel, iron was converted into malleable iron using a puddling furnace, a forging hammer and rolling mills.The puddling process was invented by Henry Cort in 1784 using coal as an indirect heat with the flame passing horizontally over the surface of the iron to oxidise and remove the impurities. This was a very hot and physically demanding process as the puddlers had to stir a ball of some five hundredweight of molten iron to expose it to the flame. The trade paper "Iron" noted in 1882 that in warm weather it was no uncommon thing to see a puddler drop down dead !

However, the Scottish iron was predominantly a foundry iron; it could not be puddled into malleable iron as well as English pig iron. In 1847 nearly 75% of the Scottish production was shipped down the Clyde to England and abroad, and Scottish foundry irons became known the world over. (As Bessemer said, as President of the Iron and Steel Institute during its first visit to Scotland in 1872: "wherever civilisation had advanced Scotch pig had formed its way".) The manufacture of malleable iron in Scotland developed more slowly, and Scotland did not take any prominent share in the big expansion of the iron rail trade. Iron puddlers were, however, brought to Scotland about 1830, and the malleable iron industry gradually established itself, usually in works separate from the blast furnaces, producing at first mainly merchant bar iron, and later, as the iron shipbuilding industry developed, plates and angles for the shipbuilding trade. The Blochairn works, of Hannay and Sons, in Glasgow was the largest in Scotland with 54 puddling furnaces and in 1872 it was producing about a third of Scottish output.

Coatbridge, with its coal and iron mines and access to markets via the Monklands Canal (which opened in 1794), had become a main centre for iron in Scotland, capitalising on the hot blast process developed by J B Neilson at Clyde Iron Works in 1828.

With the opening of the Caledonian Railway, in February 1848, and Motherwell being at a junction with the Wishaw and Coltness Railway, this also opened up access to markets for the coal and iron deposits in Motherwell and Wishaw. The malleable iron works that were started gave birth to the steel industry in the town, which later earned the town the name of 'Steelopolis'.

Probably the first malleable iron works in Motherwell was the West of Scotland Malleable Steel Co, which started in 1849. This Company erected works at Motherwell on a site adjoining the new railway. Although its chief partner was Mr James Merry MP, it was not a success and closed down in 1851. However, in 1853, the Glasgow Iron & Steel Company acquired the derelict works for £42,050. The works were managed by Thomas Morton, who improved, and patented, the refining and puddling of iron. The works closed in 1902.The Glasgow Iron & Steel Company also started another works at Netherton in Wishaw in 1859, which operated until 1930.

John Williams & Co's Excelsior Works was a medium sized malleable iron works. It started in 1866 and specialised in iron sheets, rolled in sheet mills. In 1879 it installed the first three open hearth furnaces in Motherwell for the manufacture of steel. However, its experiments with this were not too successful and other firms went on to capture the steel market. Williams went on to manufacture wire, nails, staples, rivets and washers, and was prospering in 1949.

David Colville's Dalzell Steel Works dates from 18th October 1871 and started as a malleable iron works, manufacturing bars, beams, etc. The firm switched to steel production in 1880.

Bessemer Steel - 1860s

Henry Bessemer was a prolific inventor, born in Hertfordshire in 1813. From developing a type of stamp for legal documents that could not be used twice he progressed to type-founding, from there to manufacture of a bronze powder, then taking out patents for paints, oils, varnishes, manufacture of sugar, construction of railway carriages, centrifugal pumps, projectiles and ordnance. It was while developing the ordnance it became necessary to find a stronger metal than the current cast iron. Knowing little or nothing of metallurgy he visited iron works in the North of England before converting an old factory in St Pancras, London, into an experimental iron works. After some 18 months with limited success the idea occurred to him to introduce air into the molten cast iron to render it malleable.

"The primitive apparatus being ready, the engine was made to force streams of air under high pressure through the bottom of the vessel, which was lined with fire-clay, and the stoker was told to pour the metal when it was sufficiently melted in at the top of it. A cast-iron plate one of those lids which commonly cover the coal-holes in the pavement was hung over the converter; and all being got ready, the stoker in some bewilderment poured in the metal. Instantly out came a volcanic eruption of such dazzling coruscations as had never been seen before. The dangling pot-lid dissolved in the gleaming volume of flame, and the chain by which it hung grew red and then white as the various stages of the process were un-folded to the gaze of the wondering spectators. The air-cock to regulate the blast was beside the converting vessel, and no one dared to go near it, much less to deliberately shut it. In this dilemma, however, they were soon relieved by finding that the process of decarburization or combustion had expended all its fury; and, most wonderful of all, the result was steel! The new metal was tried. Its quality was good. The problem was solved. The new process appeared successful. The inventor was elated".

As the relatively small amount of steel produced by the Henry Cort or Huntsman process was very expensive in time and fuel this single metallurgical invention, which used no fuel and took 20 minutes, transformed the cost of steelmaking. According to M. Michael Chevalier, in 1882, it had saved even more than the value than all the gold of California, which at that time was estimated as £230,000,000 !

Scotland was an early adopter of Bessemer Steel production (patented in 1855), with experiments in 1857 at Coats Ironworks and the erection of a small plant by Bessemer himself at Dixon's Govan Iron Works. However, the resulting steel was unsatisfactory, owing to the presence of phosphorus, and nitrogen embrittlement, and did not improve until R F Mushet's contribution to the Bessemer process.

Bessemer converters began to be adopted, primarily for rail manufacture, in the 1860s by John Brown and Charles Cammell in Sheffield and Alfred krupp in Essen. A large expansion then took place in England, Wales, Germany and America. Only two large works in Scotland adopted the process later, as a way of increasing the market for the output of their blast furnaces. The Glasgow Iron Company in Wishaw installed three 7 ton Bessemer converters in 1883 in order to make use of the iron rich slag heaps left behind by the puddling furnaces. However, it was eventually found that the phosphorus content of the slag was too low and the silicon content was too high and the works were converted to open hearth furnaces in 1894, by Thomas Williamson. Merry and Cunningham, at Glengarnock, also installed four 10 ton Bessemer converters in 1885, with the output going mainly to the tinplate works in South Wales.

Open Hearth Steel - 1870s

The Clyde had long taken the lead in shipbuilding and the use of iron for ships rapidly expanded between 1861 and 1871. In 1871, of a total of 196,229 tons of shipping launched at Glasgow, all but 200 tons were of iron, the others being two vessels, totalling 170 tons, of steel, and two 30 tonners. Indeed, in 1876 more iron ships were built on the Clyde than in the whole of the rest of the world.

It was the introduction of the Siemens Open Hearth Furnace, that lead to the growth of steelmaking in Scotland. This was invented by Charles William Seimens another prolific inventor. He was involved in the early development of electricity generation and was well read in the thermodynamic work of Joule, Carnot and Mayer. He was interested in the thermodynamic efficiency of processes and in ways of saving wasted heat. He developed small steam engines with a condenser and regenerators using superheated steam, which saved fuel, then in 1857, with his younger brother Frederick, he turned his attention to ways of saving furnace heat with practical applications of theoretical processes.

The furnace was developed using regenerators to recover the waste heat that otherwise went out the chimney. This was successful for small furnaces but they encountered difficulties applying the principals to larger furnaces. This was overcome by converting solid coal to gas to volatilize the fuel. An early success was with a furnace at a glass works near Birmingham in 1861. Michael Faraday was so impressed with the regenerative gas furnace that he spent two days in Birmingham with Siemens viewing the works and made it the subject of his final lecture to the Royal Institution, on 20th June 1862. The lecture lasted about an hour but unfortunately, during his concluding farewell he accidentally burned his notes and was only able to give an abstract in the proceedings.

The Siemens regenerative furnace, which was thus brought prominently before the public, consists of three essential parts. The first is the gas producer, which converts the solid fuel into gaseous fuel. A number of these are generally placed outside the works, and the gas produced by them is conducted into the works through underground channels or overhead tubes. Next, there are the regenerators or sunk chambers, which are filled with fire bricks piled in such a way that a current of air or gas passing through them is broken into a great number of parts, and is checked at every step by the interruption of an additional surface of fire-brick. Four of these chambers are placed below the furnace, and the currents of gas and air can be directed by suitable reversing valves either upward or downward through these chambers. Then, thirdly, there is the heated chamber or furnace proper, in which the work of combustion is accomplished. This chamber communicates at each extremity with two of the regenerative chambers: and, on directing currents of gas and air upward through them, the two gaseous streams meet on entering the heated chamber, where they are ignited. The current then descends through the other two regenerators, and heats them in such a way that while the uppermost chequerwork is heated to nearly the temperature of the furnace, the lower parts are heated to a less and less degree, till at last the products of combustion escape into the chimney comparatively cool. In the course of, say, one hour, the currents are reversed, and the cold air and gas ascending through the two chambers, which have been previously heated, take up the heat there deposited, and again enter into combustion at the entrance into the heated chamber or furnace at nearly the same temperature at which the products of combustion left the furnace, say 500. By the combustion of these heated gases the heat in the furnace is raised to, say, 1,000; and after that combustion the remaining products again return through the other two regenerators, heating them as they pass along, and finally escape at the chimney end comparatively cool. By this process of accumulation the most intense temperature can be attained in the furnace chamber without having recourse to gas of high quality or to intensified draught. Practically the limit is reached at the point where the materials of the chamber begin to melt; theoretically the limit exists at the point where combustion ceases, called by Sainte-Claire Deville (the point of dissociation), because at that point (4,500 F.) the two gases hydrogen and oxygen, which necessarily combine in combustion become dissociated, showing that combustion only takes place between the limits of about 600 and 4,500 F. It has been found that in a steel-melting furnace while the temperature of the melting chamber exceeded 4,000 F., the waste products of combustion escaped into the chimney at 240 F., showing that nearly the whole of the heat generated was absorbed in the furnace in doing its work. This furnace, moreover, has the advantage of preventing smoke, and of using inferior qualities of coal, or such inferior kinds of fuel as peat and lignite.

Siemens took out a patent in 1861, stating that the furnace was applicable to the melting of steel on the open hearth. He designed furnaces for a number of iron makers with limited success, due to the new metalurgy and impurities in the steel produced. In 1865 he rented a small factory in Birmingham, and set up the 'Sample Steelworks' to develop the details of the process. By 1867 he had met success, converting old iron rails, originally made at Dowlais, into steel which was rolled into rails at Sir john Brown & Co at Sheffield. These so impressed the directors of the great Western Railway that the Landore Siemens Steel Company, in Swansea, was immediately formed. By 1869 it was making 75 tons a week.

Scotland was an early adopter of the open hearth furnace, first at the Atlas Works in Monklands, and then on a larger scale, in 1871, when the Steel Company of Scotland was formed at Hallside, under the supervision of Colonel J Roper Wright, who had worked at the Birmingham Sample Steelworks with Siemens.

The shipbuilders on the Clyde were quick to adopt open-hearth steel. Although it was up to 50% more expensive than malleable iron it had better properties and was a more reliable product than Bessemer Steel, which suffered from nitrogen embrittlement from the air blow. It was also stronger thus leading to a weight saving over iron ships, increasing cargo capacity and saving through life costs for shipowners. albeit at an increased initial build cost.

Once open hearth steel was approved by the Chief Naval Architect of the Royal Navy in 1876, following tests at John Elder Company in Glasgow, the market was created. This was also an advantage to Scotland as the Bessemer process had not been very successful with the local Scottish iron ores. By 1878 the Steel Company of Scotland, still the only Scottish producers, had 14 open hearth furnaces (10 of 6 ton capacity and 4 of 10 tons). At the time there were 90 such furnaces in Britain, 42 of these in Wales.

When the demand for rails fell off, shortly after Hallside started, they turned to the manufacture of plates, bars, castings and forgings, and a plate mill was installed in 1877, to satisfy the emerging demand for plates from shipbuilders. Through the 1870s and 1880s the Steel Company of Scotland was the largest and most efficient open hearth works in Britain.

James Riley, an influential mechanical engineer, came to Hallside as Manager, in 1878, from Landore (in the Swansea valley), where he had been General Manager under Siemens. There he had met Nathaniel Barnaby's challenge for a uniformly tested steel for shipbuilding. The year he joined, despite a trade depression (one of the reasons for his move), Hallside added to its range with heavy angles, tee-bulbs and tinplate bars, and 4 further furnaces were built.

In 1879 William Beardmore built 3 open hearth furnaces at Parkhead in Glasgow, as did John Williams at Exelsior in Wishaw. In 1880 the Steel Company built 4 more furnaces at Hallside and purchaced Blochairn, where they erected 8 furnaces. Other newcomers, in 1880, were David Colville and Sons, with 4 furnaces at Dalzell, and the Neilsons at Mossend, with 5 furnaces.

The demand for ships plates led to many steelworks installing plate mills from the 1880s. In recent times there were only two plate mills in Scotland, at Dalzell and Clydebridge, however, stretching back to the 1880s there have been over 30 plate mills in Scotland, in other works such as: Blochairn and Parkhead but, perhaps less well known, also in Glengarnock, Lanarkshire, Clydesdale, Mossend, Wishaw and Calderbank works.

Of 251,000 tons of British open hearth steel produced in 1880, Scotland made 84,500 tons, only being surpassed by South Wales's 116,000 tons, although the production per furnace in Scotland was well ahead of any other area. By the following year the output in Scotland had doubled, overtaking South Wales. During the next decade, nearly one third of the total shipping launched in Britain was built (and a higher proportion engined) on the Clyde, where more than 30 shipyards provided the main outlet for Scottish iron and steel. In 1881 the output of steel shipping on the Clyde was 75,000 tons, in 1882 it was 120,000 tons and in 1883 it was 141,770 tons. In 1883 the Steel Company of Scotland's make of open hearth steel (at Hallside and Blochairn) was 144,460 ingot tons and the finished output included 56,000tons of boiler and ship plates, and 16,000 tons of angle bars, in addition to large quantities of steel castings, forgings, rails and other goods.

Amongst the first large constructions made possible by the supply of mild steel were the Forth Rail Bridge (58,000 tons in 1883-90) and ships such as the Campania (12,950 tons in 1892).

In 1892 the available capacity of the Scottish iron industry was about 1,250,000 tons of pig-iron, requiring three million tons of iron ore (two million of which were imported), two and a quarter million tons of coal and about half a million tons of limestone. The associated labour cost to produce this iron was about £1 million. At this time the capacity of the wrought or malleable ironworks was about 300,000 tons, requiring 350,000 tons of pig-iron and scrap, 100,000 tons of ore and 650,000 tons of coal. The associated labour cost of the finished iron was about £550,000. Steel capacity (Bessemer and Open Hearth) was about 900,000 tons of ingots, producing about 675,000 tons of finished steel. This required about 800,000 tons of pig-iron, 180,000 tons of ore and about 1,000,000 tons of coal. The associated labour cost of the finished steel was about £1,100,000. This full capacity would not have all been in use and normal output would have been about 25% lower.

Plate Mills in Scotland

Iron plates for shipbuilding were rolled at various works in Scotland. As Hallside Steelworks produced the first open hearth steel in Scotland for shipbuilding in the 1870s, and for the Forth Bridge in the 1880s, I realised that it had an early plate mill; but, I thought that Clydebridge, Dalzell and Blochairn had been the only works producing steel plates for shipbuilding in the 20th century. However, following some research in the Mitchell library in Glasgow, I discovered that some 30 plate mills (double click to see table) have operated at various times in Scotland, including one at Dalzell that rolled plates for the Titanic. Even now in 2011, and despite what the press would have us believe that there are no steelworks left in Scotland, the heavy plate mill at Dalzell steelworks and the plate heat treatment works at Clydebridge steelworks are still in operation, feeding the world wide demand for high quality steel plates.

Clydebridge 1887

The Steel Company of Scotland at Hallside had an initial monopoly over the market for open hearth steel. However, because of the demand from the shipyards, many other steelworks started at this time and some malleable ironworks changed to steel production. By the time Clydebridge started in 1887 the steel works could not keep up with the demand from the shipyards. Strikes were also common and wage rises of 15 to 20% were being offered to help keep production going to meet the demand. At this time the early adoption of the open hearth had given Scotland, and Wales, a lead over much of the rest of the UK. However, the initial boom lead to increased competition, and increasing production, and not all of the new works survived.

The Clydebridge Steel Company Ltd was one that only just survived, but with the intervention of WW1 and the arrival of Colvilles went on to thrive. It was started in 1887 by Messrs. Walter and Hugh Neilson, sons of the late Mr. William Neilson, of Mossend, with a sufficient number of partners to make up a private limited company, and at a cost of £90,000, two thirds of which was provided by the Neilson family. Quotes for construction of the works were obtained in 1885, and by 1887 the works were largely constructed and the workforce was being hired. The Nielson family (double click underlined text for family tree) were closely related to James Beaumont Nielson, famous for the hot blast process, first tried at Clyde Iron Works in 1828.

Hugh Neilson ran Mossend Iron Co but retired in 1886 to set up Clydebridge. The original manager of Clydebridge was James Neilson, who was regarded as being 'the most vindictive anti-trade union employer in the Scottish iron and steel industry'. This was a boom time in the industry and there had been many strikes by miners and steel workers, which had resulted in wages rising by 15 to 20 % at other works. By September 1889 the Millmen's Union had established a branch of 50 members at Clydebridge. The management gave notice to 13 of the members and the others went on strike, shutting the works for four months. All efforts to settle the dispute "by arbitration and other reasonable means" failed and "all attempts at conciliation had been met with curt refusal". Even after a change of management, labour problems continued, and efficiency was low.

James Neilson was followed as works manager by Walter Neilson, Archibald Watson and Robert Paton.

Before the First World War there was a low demand for steel and Clydebridge was closed for 5 years, from November 1907 to November 1912, under a subsidy from the Scottish Steelmakers Association to control demand.

1914 - 1918

With the outbreak of war in 1914 there was a sudden demand for steel billets to make high explosive shells and an increased demand from shipbuilding. Several Scottish steelmakers were approached by the Ministry of Munitions and David Colville and Sons was asked to lease and extend Clydebridge. However, the owners could not agree the terms so David Colville and Sons decided, early in 1915, to purchase the works. The transaction was completed in October 1915 and The Clydebridge Steel Company was liquidated in February 1917.

As soon as the decision had been made to purchase, the Clydebridge plant was examined for Colvilles, by the heavy engineering manufacturer John Lamberton. It was found to be in good condition and a start was made on the production of billet steel to make shells.

When Clydebridge Works was taken over, in October 1915, the Melting Shop contained six 40 ton and two 60 ton open hearth furnaces, and a foundation for another large furnace. A cogging mill supplied the plate mills, of which there were three, so arranged that only two were worked at one time, No2 being independently driven, while No1 and No3 (No 3 was installed in 1907) had an engine in common. The cogging mill was altered to roll 6 inch and 8 inch shell bars, and a Shell Shop erected, with six batteries of hack saws to cut the billets to shell lengths. A new 60 ton furnace was built on the spare foundation in the Melting Shop, making the total output of ingots available about 2,000 tons weekly. Extensive alterations were also carried out in other areas, with a view to speeding up the output.

Colvilles had also purchased Glengarnock Iron and Steel Company in June 1916, and as submarines had become active, the Ministry requested Colvilles to undertake large expansions, to meet the acute demand for steel plates to build Standard Ships. The enlargement of both works began in October 1916, at a cost of £1½ million. At Clydebridge new buildings were erected that doubled the size of the works. These comprised a new No2 melting shop, with five 60 ton open hearth furnaces with stockyard and producer bench, and a new cogging mill bay with soaking pits, etc. The No 3 'Heavy' Plate Mill, which was used for rolling wide plate, was dismantled and sent to Dalzell works to be converted into a new No 2 Cogging Mill, and a steam hydraulic guillotine provided to cut the slabs to length. Later, a new engine was put down at the independently driven No2 'Light' Plate Mill and the No1 Plate Mill put into good order.

The new works began producing steel at the end of 1917, and in May, 1918, the new cogging mill was put into operation. Thereafter both plate mills were kept fully supplied with slabs, and were able to produce about 1,500 tons weekly; 2,000 were now employed at Clydebridge.

Between 1914 and 1918, the three works of David Colville and Sons (DaIzell, Glengarnock and Clydebridge) manufactured:
Shell Bars 630,859 tons
Trench Rails 29,128 tons
Bullet and Bomb-Proof, and Nickel Chrome Steel
Bar, (for Aeroplanes) 9,550 tons


The steel industry expected an expansion after WW1, to replace the shipping lost during the war. However, Britain did not recover all of its foreign trade after the war and German merchant ships were sold cheaply to British shipowners as war reparations. As a result of this, and the coal strikes in 1921, many steelworks closed (temporarily or finally) and there was about 50% unemployment in the localities.

A new 3 high, electrically driven, plate mill was installed at Clydebridge in 1921-1922 to meet the expected demand for shipbuilding. However, the slump in trade closed the works for several months and the brand new mill was idle until the works restarted on the 20th February 1923. At this point in its history Clydebridge had survived its difficult early years and was now set to grow. Following a partial recovery in 1923, there was a decline in 1926 with the general strike and coal crisis. There was a recovery again in 1927 but then another economic downturn in 1930-32. Production gradually recovered again leading up to the eve of WWII.

By 1939, with hot metal working from Clyde Iron, Clydebridge became one of the largest integrated steelworks in the UK, setting world records for the production of sheared plates used to build most of the famous ships on the Clyde (and at Harland and Woolf in Belfast) such as the Lusitania, Mauretania, The Empress of Ireland, Queen Mary, Queen Elisabeth, QE2. It would reach its maximum size with the addition of the 4 high plate mill and new shearing facilities in the early 1960s, and the expansion of the heat treatment plant in the 1970s.


The peak was reached in 1977, just before the widespread closure of most of the UK's open hearth melting shops and closure of the cogging mill. At its peak it had employed 3,500 people. Clyde Iron Works was also closed, after operating for 192 years.

After this, Clydebridge continued to be supplied with continuously cast slabs from Ravenscraig, but with the demise of shipbuilding in the UK the demand for steel plates fell and the plate mill rolled its last plate on 12 November 1982.

The heat treatment and quenching plant survived as it was still new and in demand. Some of the shears plant also survived and the remaining works, run as a satellite of Dalzell works, are still in operation in 2011, some 124 years after it all started.

Although this is a brief history I do have more detailed, year by year, records of events and outputs in the melting shop, mills and shears.





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