Post 226 – by Gautam Shah
Irons include range of materials, each of which with own unique properties. The Iron, technologically arrived in this chronological order, such as Wrought iron, Cast iron, Carbonized iron (Carbon steel) and (mild) Steel.
Wrought iron is composed mainly of elemental iron, with small amounts (1-2 %) of added slag (a by-product of iron ore smelting process consisting of a mixture of silicon, sulfur, phosphorous, and aluminum oxides). Wrought iron is highly malleable material, and so can be repeatedly heated and worked with forging tools to deform and shape it. Wrought iron gains strength when it is repeated worked. Wrought iron is softer and more ductile as contains little carbon than Cast iron. It is also highly resistant to fatigue, when large amounts of pressure are applied. Wrought iron structures pass through large deformations, before failing.
Wrought Irons are Magnetic, exhibit high elasticity and tensile strength. Wrought can be used for tension or compression (in comparison, the cast iron is suitable for compression only). First wrought items were Nails, Spikes, Clamps, Rivets, Chains, Tie rods (for arches and vaults), bulb-tees and I-beams. Other uses of wrought include, Fences, gates, grills, railings, balconies, verandas, canopies, statuettes, crests, and tools. Wrought iron is susceptible to chemical corrosion. Stressed areas are prone to cracking or chipping.
Wrought Iron lattices have been used primarily over windows, doors and other gaps. Latticed structures of wrought iron are used for balconies, as space dividers, church screens, vine climbers, stair railings, estate gates and barricades, frames for furniture items, lintels, beams, brackets, columns and for garden structures like orangeries and pavilions.
Iron forming reflects man’s innovative and craft skills. It has been a very difficult material to work with, as it presents different behaviour in its various forms. Yet, it has been cast, resealed, joined, spliced, chased and engraved. It has been reformatted with hot and cold treatments. Wrought iron has been used for household utilities, tools, vessels, arms, building elements, architectonic entities, decorative items and statuettes. It has replaced wood for its stability, strength and malleability.
Before the Middle Ages, wrought iron was used primarily for weapons, tools and utilities that only could be made with a metal. Unlike Cast iron, Wrought iron has a lower carbon content. It is stronger, non-brittle, and could be forged to any shape, and join by beating. Literally, Wrought iron means an iron that can be worked, both in hot and cold forms.
One of the most creative forms of wrought iron manifests in trellis, grills, and other hollowed or pierced-out planner forms. Earlier trellis or grills were formed of wood, bamboos, vines, and cast of copper or bronze, or even of ceramics. These materials were not amenable to plastic shaping. Wrought iron has been used as a plastic material to form variety of trellis, in simple or multi-curved planner forms and also mould sub-elements differently.
The first lattices were functional elements like the protective cover within gaps, and in doors and windows. Simple linear cast or forged elements were inserted in side structures of masonry or wood. These, however, soon became interlacing or entwined entities of bars, hot-forged or riveted forming a grill. Same techniques were used for creating grills for hearths and sieves.
Wrought Iron lattices began to be used 13 and 14th C windows of mansions and cathedrals requiring high security. Same structures were used as barricades and partitions. The lattices were designed with variegated shaping of bars’ profiles, and in terms of angle and spacing. Hot-forging and cold working methods were used to alter the sections and shapes of the linear elements. Round and square rods and bars were twisted, coiled and beaten into complex foliated forms. Iron pieces were chiselled, chased, riveted, shape forged. Iron plates were also used for plate like tracery elements. Ends, finials and cresting were cast from other materials like brass or bronze and mounted over steel roods. Riveting and hot forging was chief techniques of joint making. Joints, However, were so skillfully concealed that the grill seemed like one cast or formed piece.
Wrought ironwork began to serve other decorative purposes. Famous cathedrals and other public buildings ( Canterbury and Winchester Cathedrals of England and Notre Dame de Paris) have extremely crafty pieces wrought iron works.
Wrought Iron lattice work, began as a rough surface entity, but by end of middle ages, the surfaces were well formed, ground and joints were concealed. Surfaces were often chased, engraved, inlayed with materials. Finials, caps and other elements of brass, copper, bronze and gold were added. Ornaments were forged out as separate parts, and assembled with riveting, or welding. Decorative elements, such as of flowers, leaves, vines, birds, names, and coats of arms, were bunched or heaped to provide a composition language.