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British Celts & History / Development of Iron. FineIron UK

 

FASCINATING FACTS & THE STORY OF IRON

 

WROUGHT IRON

Wrought iron has been used in building from the earliest days of civilisation, wrought iron door furniture being commonplace in Roman times. The structural use or iron gates from the middle ages, when bars of wrought iron would be used occasionally to tie masonry arches and domes. This use of wrought iron in tension guaranteed its use throughout the ascendancy of cast iron in the canal and railway ages, as cast iron is strong only in compression.

After the introduction of mild steel, which can be mass produced and therefore comparatively costs much less, wrought iron, and the craft skills associated with it, gradually disappeared in accordance with the general decline of craft standards in the twentieth century, until the last ironworks ceased production in 1974.

Most true wrought iron (puddled or charcoal) is now reserved for heritage and restoration projects with only one supplier of genuine wrought iron remaining worldwide.

When the term ‘wrought iron’ is used today, usually it refers to any metalwork that has been ‘worked’ or shaped in a decorative fashion by a blacksmith or metalworker. Many products that are described as wrought iron are actually made from mild steel.

RECOGNISING WROUGHT IRON

Wrought iron is unlike cast, in that it is not brittle and seldom breaks. For this reason, wrought ironwork is frequently far more delicate, although years of paint can obscure this. Cast iron is most frequently identified by its repetitive nature, and forms which could be carved in a wooden pattern, but not made by hammer and anvil.

Wrought iron can be dated, approximately by its texture. Until the very end of the eighteenth century, sections of wrought iron were derived by forging of billets by hand or water power, this resulted in a more or less uneven surface texture, and very sharp corners. A foreshortened view of a bar displays well the irregularities of the surface. Rolled bars, on the other hand, produced from the beginning of the nineteenth century, are perfectly smooth, and the corners can display a small radius. Nineteenth century wrought iron is known as ‘puddled iron’.
Telling wrought iron from mild steel is often more difficult, as both will bend and not break. One of the easiest identifying factors is evidence of electric welding.

Mild steel has in the past had more active corrosion, we have all seen rust at the joints of a steel gate etc, but this is no longer a reliable identifier as with the continuing development and improvement of paints and finishes (such as metallisation) and provided a small amount of maintenance is carried out, there is no reason why mild steel shouldn’t be as long lasting as wrought iron.

It’s an established fact that true puddled wrought iron has properties that made it more resistant to corrosion, however all new wrought iron is in fact not new at all, as it is produced by re milling and rolling older scrap wrought iron, in our experience and the experience of others, it has a tendency to delaminate from itself and needless to say this could potentially provide ingress for water and thereby provide greater risk for corrosion.

MILD STEEL – A MORE MODERN METAL

Mild or low carbon steel is formed from iron containing a small percentage of carbon (approximately 0.05%-0.25%). It is now the most common form of steel used as it has similar properties to wrought iron – in that it is malleable and ductile and suitable for many applications but unlike wrought iron, it is more cost effective as it can be mass produced.

Steel was produced in bloomery furnaces for thousands of years, but it wasn’t produced on the industrial scale it is today until the 17th century after more efficient production methods were discovered, including the production of blister and crucible steel.

The invention of the Bessemer process in the mid-19th century, saw a new era of mass- produced steel! It takes its name from Henry Bessemer, who took out a patent on the process in 1856 (it was also said to have been independently discovered by William Kelly, an American inventor in 1851, though there is little evidence to support the claim). The key principle of the process was the removal of impurities from the iron through oxidisation – blowing air through the molten iron. The process was refined over decades, thus improving the quality of the steel produced and with these improvements for the most part, mild steel replaced wrought iron.

Basic Oxygen Steel (BOS) was developed in 1948 by Swiss engineer Robert Durrer and commercialised between 1952-53 by Austrian steel making company VOEST and ÖAMG. It is a refined version of the Bessemer converter, blowing oxygen through the molten iron instead of air. This largely replaced earlier methods by further lowering the cost of production and increasing the quality of the final product.

 Modern furnaces have the ability to take a charge of iron up to 400 tons and convert it into steel in a mere 40mins (approximately) compared with the 10-12 hours it would take in an open hearth furnace! Today, steel is one of the most common manmade materials in the world, with more than 1.6 billion tons produced annually!

METALLISATION

This is the general term given to describe the technique of coating the surface of an object with a layer of metal and is a process that can be traced back to 1835 by coating glass with a layer of silver to create a mirror. Metallisation can be for decorative, functional or protective purposes and there are numerous metallisation techniques including:- Vacuum metallizing, Arc spray, Flame spray, silver reduction metallization, thermal spray and cold spray. Any metal can be used for metallisation

Thermal spraying

This technology improves or restores the surface of a solid material and is most often used to protect against corrosion, abrasion, heat, cavitation and general wear. Although there are variants to the method of application, the overall process remains the same. All methods involve spraying small molten particles onto a pre prepared surface where they cool and adhere to form a continuous coating. Thermal spraying can provide thick coatings ranging from 20 microns to several mm thick (depending on the process used)

Cold spray

Unlike thermal spraying, as the name suggests cold spraying does not involve heat and the method was discovered and commercialised in the 1990’s. Solid powders only micrometers thick are accelerated in a supersonic, high velocity gas jet and upon impact with the material being sprayed particles undergo plastic deformation (meaning the particles change shape/size) and adhere to the surface, though the powders do not melt during the spraying process. It has several advantages over thermal spraying including :- minimal surface preparation required, low energy consumption, no toxic wastes and the ability to collect and reuse 100% of the particles along with the advantage of being able to spray surfaces that are thermally sensitive 

 

IRON & CELTIC HISTORY

Much of what we know about the Celts has been learnt through oral tradition. It is thought that the name given to them by the Greeks – Keltoi – means ” hidden people ” due to the reluctance of the Celts to commit any of their vast wealth of knowledge to writing.
What we know of their early history has been largely learnt through archaeological excavations of the settlements and burial sites found across Europe.
The Celts probably descended from Stone Age peoples of Europe, who began to populate the continent about 10,000 BC.
At the start of the first millennium BC the Celts possessed great skill in metal work, especially wrought iron, and by the 6th century BC they had a formidable armament of spears, swords, axes as well as agricultural implements. By 450 BC new centres of Celtic civilisation emerged and increasing mastery of iron work led to specialisation – wagon makers, shipbuilders, wheelwright etc – Amid this increased productivity an artistic style emerged; ” La Tene ,” design was bold and complex, and quickly became dominant throughout Celtic lands. Celtic affluence grew, and around 400 BC Celtic tribes crossed The Alps, sacking Rome in 391 BC and settling in Northern Italy.

A century later they pushed into Greece and Asia Minor and by 250 BC ” La Tene ” culture was at its height. The Celts resumed full scale trading over their old trade routes and by the second century BC new established fortified towns replaced many of the old hill forts, abandoned in the fifth century BC. Serving as centres of commerce and manufacture they were immensely lucrative; however Celtic trade grew increasingly dependent on Roman markets.

In 192 BC Rome established its supremacy and later conquered the area of Southern France we now know as Province. By the mid first century BC the Romans began their assault on Western Europe. With their loyalties still tribal rather than national the Celts were unable to mount a unified resistance.
Gradually the Celts adopted the ways of their victors but Celtic Culture remained dominant in Britain until AD 43 when Rome conquered the Southern half of the island. Ireland then became the bastion of the Celts until it’s fifth century conversion to Christianity. Even after that, tribal memories held on to Celtic languages and legends, which were at last written down by eight-century Irish Christian clerics.

 

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