Post 628 –by Gautam Shah




  1. FORGING >
  2. COATING of METALS – 1 >
  7. METAL WORKING Processes >
  9. HAMMERS >
  10. DRILLING >
  13. SMITHY >
  14. CARBON and STEELS >
  17. IRON or STEEL -technologies through history >
  19. ALLOYS >
  21. ALUMINIUM BRONZE alloys >
  23. GILDING >
  25. METALS and ROOFS -Part – I >
  28. PATINA >
  29. COPPER -1 >
  30. COPPER -2 Copper Compounds >
  31. COPPER 3 -Bronze alloys >
  32. TIN >
  33. PEWTER >





Post 540  by Gautam Shah


First iron used by ancient people was a meteoric source, an iron alloy with nickel. This was used several millenniums before the actual iron age. It was a natural Iron in metallic state and so required no smelting of ores. This nearly pure iron is softer than bronze, and therefore tools formed of it had soft wearing edge.

Ahnighito fragment of the Cape York meteorite. Wikipedia Flickr image by Author Mike Cassano

Primitive age iron was smelted by mixing iron ore with charcoal, and burning in bloomeries, a type of furnaces where bellows were used to force in the air. The carbon monoxide produced by the burning charcoal, reduced the iron oxide ore to metallic iron. The apparatus, however, did not achieve a temperature of 1540° C, to completely melt the iron. The metal collected in the bottom of the furnace remained as a spongy non homogeneous mass or bloom. It had high proportion of intermingled slag. The blooms were repeatedly heated, beaten and folded to remove the slag. This produced wrought iron (=worked iron), a malleable, but fairly soft material. Iron age Irons were not castable products but required hot forming (forging). This was mainly due to inability to fully melt the material. Hot forming was a labourious process, requiring skill and experience. In comparison to bronze, iron ore was procurable everywhere and cheaper to process.

Willamette Meteorite, the sixth largest in the world, is an iron-nickel meteorite Wikipedia image by Author Dante Alighieri

Wrought iron shows high resistance to corrosion due to the trapped slag in the metal. The presence of slag in the iron helps fusion joining by hammering or forging. Wrought iron is no longer produced commercially, because low-carbon steel is less expensive and is of more uniform quality. Wrought iron, however, is still produced for certain craft-based uses such as making intricate craft objects balustrades, gates, garden accessories, etc.

The Ashoka iron pillar New Delhi, India wikipedia image by Mark A. Wilson

Simulated form of wrought iron is made by melting scrap mild steel in small furnaces, blowing air through the melt to remove carbon, and pouring the molten metal into a ladle containing molten slag, which is usually prepared by melting iron ore, mill scale, and sand together. When the molten iron carrying a large amount of gas in solution, is poured into the molten slag (kept at a lower temperature than iron), the metal solidifies almost instantly, releasing the dissolved gas. The force exerted by the gas shatters the metal into minute particles that are heavier than the slag and settle at the bottom of the ladle, agglomerating into a spongy mass.

Silla iron armor, en:Three Kingdoms of Korea, 3rd century Wikipedia image

It was Chinese (1200 BC or earlier) who designed kilns that could raise the temperature for iron making. These kilns, used upgraded coal and had high volume air supply for efficient burning. Chinese were able to melt the Iron and cast it into desired forms. Casting was less labourious, and allowed multiple items with same die form. It was accurate than forging each piece. Chinese smiths melted wrought iron and cast iron together to produce steel -a material of controlled carbon content. The process was called ‘harmonizing the hard and the soft’. This was widely used for casting cooking pots and iron statuettes. A cast iron is harder than wrought iron, but maintains the cutting edge.

Casting pig iron, Iroquois smelter, Chicago, between 1890 and 1901. Wikipedia image

Perhaps as early as 500 BC, although certainly by 200 AD, high quality steel was also produced in southern India by the crucible technique. In this system, high-purity wrought iron, charcoal, and glass were mixed in a crucible and heated until the iron melted and absorbed the carbon.

Carbon content of iron is a major factor that creates harder material. It was necessary to absorb more carbon in the iron. This required higher ratio of fuel to ore, and push in a lot more volume of air. The strength of iron begins to increase with carbon contents of 0.5 percent. To heat treat iron a carbon content of 1.2% was necessary. Wrought iron which contained less than this proportion had no qualitative effect due to heat treatments. A higher carbon content creates a brittle material but allows heat hardening. ‘Iron hardening by quenching was not practised because it made iron very brittle, unless followed by tempering, or reheating at a lower temperature, to restore toughness’. Simple fire, 600-700° C, based technique of repeated cold forging and annealing was used.

cast iron columns line the Albert Dock’s quayside Wikipedia image

In the pre-Christian portion of the period, the first important steel production was started in India, using a process called Wootz steel. It was prepared as sponge (porous) iron. This was hammered while hot to expel slag, broken into smaller pieces, and placed with wood chips in clay containers, and heated. On melting, an iron composition containing 1 to 1.6% carbon was produced. The pieces were reheated to form articles that required a hard body and sharp edge. Such steel products were exported to Middle East and other countries. It was known as Faulad (Persian). (Faulad or wootz steel has a Kannada term, ukku, a Language of Indian region of Karnataka).

Elevator screen from the Chicago Stock Exchange cast iron electroplated with copper. Wikipedia image by Joe Mabel

Nowadays commercial steel plants produce ingots or pig iron. It has very limited use. It goes to casting foundries or to steel mills. At both the places it is remelted to reduce its carbon content and for allying by adding various elements such as manganese and nickel. Often scrap steels are also added for the same purposes.

Black Country Living Museum – Jerushah the Tilted Cottage – cast iron cooker Flickr image by Elliott Brown

Melting points for various forms of Irons

Iron, Wrought     1482 – 1593

Iron, Gray Cast   1127 – 1204

Iron, Ductile       1149

Steel, Carbon      1425 – 1540

Steel, Stainless   1510



Post 396 – by Gautam Shah 


Smithy is a work-place where metals are worked by heating, casting, and hammering (forging) for quality modification, shaping and joining. Copper, bronze and silver were some of the first metals handled in workshops. Smithy is called a Forge. But bronze is not as malleable as copper or silver, and it was not readily forged or chased, but cast. Copper was shaped by forging. The traditions of metals like bronze and copper helped man to deal with cast iron –a castable metal, and little later wrought iron –a workable metal. The term to wrought derives from work.

typical smithy in Finland

A smithy is also called a forge, as hot shaping or forming is chief the activity here. The metal workshop processes are associated with hearth, a place to hammer, chisel, punch, shear bend a piece of iron, and water or oil for quenching the item.


Metal pieces are heated to a temperature range at which work hardening does not happen. The heated metal piece is held with tongs and taken to the forge. Here the work-piece is held with tongs and other types of holders while forging. The heating and forging sequence is repeated several times, to maintain the temperature. The piece is than taken to a tub of water (or oil) for quenching or rapid cooling.

Iron Forge

Once upon a time forging workshops were independent units, owned by a smith and serving variety of needs of a neighbourhood. These needs were cooking vessels, plates, bowls, spikes, nails, cart axles, horse shoes, agricultural implements, tools, etc. Iron smiths were employed at construction sites to produce architectural entities such as lattices, screens, partitions, fences, stairs, balcony railings, horse appointments, weapons, posts, and building hardware, etc. ‘Locksmiths’ were fine crafts persons, with capacity to devise clocks, locks and other gadgets. Their ability was to rework a smithy item to finer details and embellish it with many different materials and techniques.

Blacksmith at work

Iron Smiths in later part of 18th C also began to work with rolled metal sheets, items such as trunks, cabinets, truck and other vehicles bodies, buckets, vessels, etc. These items of rolled metal sheets were cold-worked, and did not require any forging. Similarly Iron smiths began to be employed on construction work sites for cutting and rivetting rolled steel structural assemblies.

A smithy or forge has following tools and facilities. Some of these are now made from very superior materials and automated.


A Hearth is a place where coal, charcoal or other fuels are burnt. It is designed to contain and control the fire by amount of air, volume of fuel, and shape of the flame or heat spread. The hearth is aided by a Tuyere (a pipe through which air is blown into fire) and Bellows or blower (for forcing air into the tuyere). Bellows were once made of leather, and blowers are fans moved manually or by power. The hearth fire is used for effecting metallurgical changes like hardening, annealing, and tempering, etc.

Working at Anvil

An anvil is a block on which forging is done. It is placed as very steady piece and used as a support for all metal manipulations. Its size and shape vary according to the weight of work piece and nature of operations. Most anvils have a wide base for stability, a body, a flatter main work face, projection called horn, and variety of edge forms, holes and depressions.

Tongs are used for holding, carrying and turning a hot metal piece. Tongs have similar mechanisms, that is long arms but variety of holder mouths. Vices are clamping devices mounted on work bench end.

Chisels are used for cutting and chipping, but separate for hot and cold work. Punches are like chisels but blunt edged for forming holes or depressions. A drift is a large sized wide cone punch used for enlarging punched holes.

Hammers for smithy

Hammers for smithy

Hammers are called a smith’s hand. Hammers have different weights of heads, types of head formations such as pean, eye, cheeks, face, and lengths of handles. A crafts person on own uses lighter to medium weight hammer as other hand is used for holding the iron piece in a tong, whereas an assistant uses both hand for a heavier sledge hammer. Nowadays power hammers are used.

Modern smithy have other facilities like lathes, drilling, shearing, punching machines, cutting saws, grinders and welding equipments.

This article on IRON SMITHY was published on my other Blog >>>

IRON or STEEL -technologies through history

Post —by Gautam Shah



       Iron or Steel is one of the most complex of all metals used by man. In spite of its very large volume of use, it still remains a very enigmatic material.


2     It changes its properties during manufacture, post processing, aging and usage. Many of the changes are known to man for years, but ignored. Some of these effects became apparent very late in the life span of the structure, or functional entities. Such realizations, though late have not affected us very severely, because superior technologies of later dates provided better guaranteed and efficient solutions.


       Many of the Industrial revolution period steel structures, such as large span buildings, bridges and ships were formed of very inferior materials and fastening techniques (hind sight realizations). But ‘change solutions’ that became available 30 / 50 years later were better enough to have no regrets for replacement. In few cases there have been losses of life, such as Titanic or Liberty series of ships. The only regrets were that often such structures collapsed suddenly.


4        The technological deficiencies that affected the structures and entities were due to ignorance and lack of inadequate knowledge, but similar problems have continued even today due to insincere applications.



5       However, birth of steel fabrication was with cast shapes like parts of columns, capitals, brackets and sections of arches. These were components of compression. Tensile capacity was untested. Hollowed out brackets and arch forming sections had few subsections that were tensile stressed. Tensile behaviour of steel was not completely unknown quality. As the integrity of castings improved, through constitution and methods of cooling, the tensile reliability increased.


6        One of the most widely used form of ferrous metal has been the sheets. Sheets are re-rolled, cut into strips and folded or formed into various sections.


7        Compared to cast steels, drawn steels had better grain alignment and tensile strength was known. Mild steels produced through use of Bessemer process provided the much needed ductility and tensile stress capacity.


       Steels were re-rolled into sheets, but in the manufacturing number of annealing, tempering, hardening processes were perfected.

9        Annealing and Hardening, are nominally considered two extreme processes, former a softening and the later its opposite method. But Tempering that is readjusting the quality of steel is now considered even more important. It is chiefly used in forming various sections, automobile bodies and cages for white-goods. Companies producing furniture, automobiles and white-goods have a selfish interest in replacement markets, and so design their product for 10 years life cycle. After that no one is bothered about the product.