A PRELIMINARY REVIEW
CAST IRON DEFINITION
HISTORY OF DEVELOPMENT
Cast iron is a saturated solution of carbon in iron. The
content varies from one and a half to four percent depending on other
impurities. Cast iron is hard, brittle, non-malleable and very fluid
when melted. It is extremely suited to casting into complex forms.
Cast iron is produced in a foundry by re-melting pig iron
or pig iron and scrap in a cupola and pouring into moulds. The moulds
used are specially prepared sand formed around wooden patterns. Wood
was used for the patterns because it was easily worked, but for
frequently used patterns metal was sometimes used for durability.
Very intricate patterns wTere sometimes made of wax, wood and metal.
The characteristics of the metal castings depended on the ingredients
in the iron. The more carbon in the iron, the harder it was. Silicon
made it softer, and phosphorous and sulphur make it brittle. Sulphur
also contributes to corrosion of the iron if too much is present.
Cast iron is harder and more brittle than mild steel, and it cannot be
forged or bent. Casting can be easily filed, drilled, tapped or
machined. It requires bolted or screwed connections, for it cannot
HISTORY OF DEVELOPMENT
The earliest examples of iron are believed to have come from
meteors and were broken or chipped of by the men who discovered the
meteor. At this point, men thought the iron was a gift from
the gods. Later the early campfires were accidental sources of
iron as the metal melted from ironstone inadvertently used to ring
the fire. When the fire had gone out and cooled, the molten iron was
found in the bottom of the campfire.
The first crude furnaces intended to produce iron were simply
improvements on the campfire. Areas would be scooped out to collect
the molten metal and the effect of blasts of air was discovered.
Sometimes holes would be left to blow in air, and sometimes the
furnace would be placed to receive natural wind currents.
The ages of development of this technology varied widely over
the world. It is estimated that the Mayan's were still neolithic
as late as 400 A.D. when most of Europe had moved from the Iron Age
to the Bronze Age.
Some examples of the state of iron use are as follows:
Egypt Evidence of iron beads was found as
early as 4000 B.C. Iron was found in the Great
Pyramid in the form of a tool dating to 3100 B.C.
An iron wedge was found with a copper adze which
dated back to 2800 B.C.
Assyria Iron bars from twelve to nineteen inches
long by about two and a half to five and a half
inches were found in the Palace of Sargon.
Iron at this time was forged into bars for trade
and ease of transportation. This was in Sweden
and Finland as late as 1900 A.D. The use of iron in
Assyria dated back to 2000 B.C.
Indo-China Weapons wore in use here between
2000 and 1000 B.C. Records show that China levied
a tax on iron in about 675 B.C. Evidence
of casting by patterns and sand moulds has
Europe It is thought that the Creeks were
the first to use iron in Europe. Homer, Vrigil,
Aristotle and Pliny wrote about the- :;e of it.
Aristotle writes about the different types
of iron and how it was smelted. The Romans
also had a good knowledge of metallurgy.
Britain Britain was famous for using iron in
chariots during the pre-Roman period. After the
Roman conquest, Britain was developed as a major
producer of iron. The Roman occupation had a
stimulating effect on British industry later
because it developed reserves of skill and
knowledge which would emerge.
The process which took place to produce iron in the I th and
16th centuries was basically to crush the iron ore and mix it
with marl and lime to hold it together. The resultant mix was
divided into lumps and surrounded by charcoal in a forge.
A bellows was used to force air over the fire until the substance
became spongy or pasty. In this state it was taken out and
hammered and reheated successively to beat out the impurities.
As might be imagined there was a great deal of waste in this
procedure and quite a low yield.
The early furnaces were built of clay several feet tall and
the ironstone and charcoal stacked in alternate layers. The
furnace was fired for several hours and then torn apart to
reveal, hopefully, the block of iron.
Better and more efficient furnaces were b.-,lt of masonry
later, but when the temperature got too hot the iron would
dissolve some of the carbon and run out the bottom of the
furnace. The molten iron was thought to be useless and it
was some time before this fluid iron came to be a desired product.
Probably the oldest piece of cast iron in Britain is the
Joan Collins grave slab which dates about 1350 A.D. (Grave slabs
were a chief product of early cast iron.) Most of the early
molten iron was cast into moulds to be refined into wrou ht iron
later, since wrought iron was the material in demand.
Ironmasters did discover the usefullness of cast iron finally,
and a patent was granted to Lord Dudly in 1621 for use by his
son, Dud Dudley, of a process using coal as a mineral fuel. The
real growth of the cast iron industry began around 1650, and in 1676
Abraham Darby was born. By the early 1700's Darby was experimenting
and finally became the first man to smelt iron ore with coke.
By the 18th century cast iron was being used for machinery
such as the Newcomen fire engine. In the drought of 1743, one
of the Darby's used fire engines to pump water to drive the
bellows at the ironworks. This became a study in perpetual
development iron lead to cheaper engines, which wereised to
make more iron, which was used to make cheaper engines, etc..
USES OF CAST IRON
Prior to 1750, there was very little use of cast iron in
architecture and engineering. By the end of the 1700's, however,
the were many foundress going strong to produce the material needed
by the many experimenters who came along during this period. (Some
of these foundries were in the hands of the same families as late
as twenty years ago.) Between 1750 and 1800, many experimenters
recognized the potential of cast iron and used it in bridges,
locks and gates, beams, limtels, columns, rails and decorative
elements. Some of the earliest uses were in the bridges the
English erected at Severn which still stood in the fifties.
Thomas Telford designed many bridges which uutilized the properties
of cast iron, and did not imitate other building materials such
as stone. Several examples of Telford's bridges still exist.
One of the first buildings was a mill in Manchester by Phillip
and Lee which was a model for twenty years. The decorate ve use
of cast iron created a vast demand for the material. Some early
decorative railings were used in St. Pauls and can still be seen
there.. The earliest example of columns can be seen in the
Cistercian Monastery in Portugal where the hold up the hearth hood.
Other early cast iron columns may be seen supporting the galleries
at St. Anne's in Liverpool. A well known use of cast iron as a
structural element was the Brighton Pavilion by John Nash.
In America, one of the earliest attempts to make iron
was at Falling Creek near Jamestown. Some colonists took samples
of the iron they made in America over to England and solicited
workers to return with them and open plants in New England. Two
such important plants were in Massachusetts, one at Lynn, the other
at Braintree. These works were comparable to their English
counterparts in all respects.
By 1750, American iron was cheaper than imported iron. The
bulk of production was hollow ware, but the German's in Pennsylvania
became noted for their firebacks. Production was spurred by the
Revolutionary War and American technology was on a. par with that
in England. The use of catalogs for listing products was a
big factor in increasing the demand for cast iron.
A number of slides were used in this report to illustrate
other developments and examples such as the extensive use of c'ist
iron in the architecture of New Orleans. Almost every product can
be seen in the cast iron fare of New Orleans, except for structural
cast iron. The water works was the major example of the structural
use and apart from it examples are rare.
One of the prime movers in cast iron architecture was J.mes
Bogardus. He expanded the use of cast iron into total buildings.
See Bogardus' publication, Cast Iron Buildings; Construction and
Advantages. To of the major reasons why Bogardus's buildings
were so popular were speed and economy of erection.
Though cast iron was a remarkable material for its day, and
its advantages fostered its widespread acceptance, the same rapid
technological development which made large scale production possible
was at the same time producing the new alloys and metals that would
replace it. As the 20th century arrived, cast iron as a building
material was almost entirely replaced by rolled iron steel
products which were stronger and more workable. It became possible
to produce metals which were specifically suited to the tasks
required with new processes and metallurgical knowledge.