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This page is part of a website based
on the life and achievements of eighteenth-century inventor Henry Cort. Please email site controller Eric Alexander
with any comments or queries. |
PUDDLING AFTER HENRY CORT
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All the iron for ships, bridges,
railway rails, tyres and axles from the Workshop of the World and which made possible
the industrial revolution, was manhandled at the end of long bars and poles
of various kinds in great glowing balls of metal weighing about a
hundredweight a piece. From W.W. Jenkins, Death of the Puddler. |
The most reliable evidence about the spread
of puddling is that collected by Charles Hyde.
He reckons that only four works are
puddling when Cort's business collapses in 1789.
There is Cort's plant at Fontley, which is puddling
successfully using old cast iron recovered from the Navy.
At Rotherhithe, Cyfarthfa
and Penydarren they are trying to puddle coke-smelted pig.
Rotherhithe gives up shortly after the Cort collapse. While the other two establishments work to improve the process, two
more take it up.
First is James
Cockshutt's family base at Wortley near Sheffield. Hyde says they install their puddling
furnace in 1790.
Doubtless they are following James's
advice. He returns to Wortley when
Crawshay breaks with him in 1792.
The other early puddlers are at Pentyrch,
north of Cardiff, where a furnace is installed at the end of 1792.
Hyde's story that Wilsontown
starts puddling in 1789 is refuted by other evidence.
All these ironmasters face a problem not
encountered by Cort, who has been working with iron originally smelted using
charcoal. But their starting material (“grey
iron”) is coke-smelted, and contains impurities (later found to be rich in
silicon) that accumulate in the puddling furnace, causing the quality of its
output to deteriorate.
Richard Crawshay’s Letterbook
gives an indication of some of the attempts to improve the process at Cyfarthfa. It seems that Samuel Homfray is bent on
similar work at Penydarren. Although
Crawshay and Homfray are frequently at loggerheads, it looks likely that any
improvement made by one will be quickly picked up by the other, so it is difficult
to assign credit for the adaptations that emerge.
Those adopted at Penydarren are given in a
document published in 1806, and submitted as part of Homfray’s evidence to the 1811-2 inquiry.
The procedure described differs in two important respects from that
patented by Cort.
The first difference is a preliminary
refining stage (similar to the first stage of the Wright
& Jesson process), when siliceous impurities are removed. The product is known as white iron or finer’s
metal.
The other difference is further purification
of the shingled product by rolling it flat, then cutting it into slices which
are piled, re-heated and re-rolled.
This stage can be repeated once to maximise purity, but further repetition
has negligible effect. Final rolling is
done with the shaping rollers introduced by Cort.
Though the origin of these adaptations
cannot be certain, researcher Paul Luter has uncovered fresh evidence
suggesting that at least one is the work of Homfray’s employee Joseph
Firmstone, who later sets up his own works using the process in the West
Midlands.
By 1796 the new process is well
established. 
Over
the next two years both John Wlkinson and William Reynolds introduce it at their works. Dowlais takes it
up in 1801.
It is disputable how much of the increase
in wrought iron production over this period is due to puddling. But it is deemed significant enough for
ironmasters to raise a subscription for Cort’s widow
in 1800.
The coming of the railway brings a big
boost to wrought iron production.
Cyfarthfa, Penydarren and Dowlais all benefit.
Meanwhile
Joseph Hall comes up with a significant improvement at
his Tipton works.
Called wet puddling or pig boiling, it adds
a new ingredient to the mixture in the furnace: iron coated with iron oxide, which
is more effective than air in removing the carbon impurity and does not require
the iron to be refined first.
By the middle of the century the Hall
process has been taken up by most works.
It is well covered in descriptions of puddling after this period (there
is a detailed one on the Sirhowy Valley
website).
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The largest ironworks had batteries
of blast-furnaces – up to 18 at Dowlais, where 6000 workpeople were employed,
in 1842 – and dozens of puddling furnaces.
From Crouzet, The First Industrialists: The problem of origins
(Cambridge 1985). |
In 1865 there were 2,116 puddling
furnaces in existence in the Black Country, with a potential output of 20,000
tons of finished iron a week.
From Gale, The Black Country Iron Industry, p104 (London 1966). |
In the second half of the eighteenth
century the forward march of puddling is thrown into reverse by new processes
for steelmaking.
These not only produce a more useful and
versatile output. They rely far less on
the skills of workmen.
Nevertheless puddling continues on a small
scale until the 1970s, and a relic of the last puddling works can be seen at
the Blists Hill site near Ironbridge.
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A puddler would normally be expected
to work six 12-hour shifts a week, during each of which he would be expected
to puddle six heats of 3¾ cwt of iron.
Puddlers were always in demand, and more than most skilled workers they
tended to migrate in search of higher wages.
It was a particularly strenuous occupation and the puddler's working
life was normally reckoned to be over by the time he reached 40. From Barrie Trinder, The Industrial
Revolution in Shropshire, p167 (3rd Edition, Phillimore 2000.) |
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RELATED TOPICS Cort’s promotion
efforts 1783-6 Shropshire
and Staffordshire ironmasters Cumbrian
ironmasters: Wilkinson etc |
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