Steel on film: the white heat of change

As our celebration of a century of steelmaking on screen gets underway, UCL’s Mark Miodownik explains how steel and celluloid share the same awesome power.

Mark Miodownik
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In 1963 Harold Wilson, the then leader of the Labour Party, gave a speech in which he talked about forging Britain in the “white heat of technological change”. He was referring to the intense, blinding heat given off during the steelmaking process when oxygen is blasted through cauldrons the size of houses, each brimming with molten steel.

To witness such an event is awe-inspiring, humbling and mysterious, as the films in the BFI’s This Working Life: Steel season document. White heat is an unfamiliar beast, outside of all normal experience: it will destroy almost anything in its path but is nevertheless the making of steel, giving birth to this most important ingredient of our modernity.

There is another material at the heart of these films, not seen but no less important: the celluloid on which the events are recorded. This plastic is also capable of creating white heat, terrifyingly so. The early history of cinema is punctuated by tragedies in which audience members died in the flames and smoke produced when film accidentally ignited in the projector.

The material is a form of nitrocellulose that burns fiercely not just in air but even underwater. This sinister property highlights the dangers of nitrate celluloid and is why the BFI keeps its collection of celluloid films such as these in the National Archive’s master film store at temperatures of -5ºC and at 35 per cent relative humidity.

Steel (1945)

Steel (1945)

These two materials shaped the 20th century but they were inventions of an earlier time. It was the synthesis of celluloid in the 1870s that made cinema possible at all; by replacing glass as the photosensitive transparent material for photography, film – which could be rolled onto reels – made moving images a practical proposition.

This was also a revolutionary time for steelmaking. Before this period, steel could be made only by hand and in small quantities, as it had been done for thousands of years. In contrast iron could be made easily by the bucketful, but when cast it became mysteriously brittle. The reason for the brittleness was the high percentage of carbon in the liquid metal, but no-one knew how to control it to create steel in the liquid form required for mass production.

But the advances in the understanding of chemistry that made new materials such as celluloid possible also provided the answer for steel, in the form of the Bessemer process. This required the blowing of air through huge buckets of liquid iron. The oxygen in the air chemically reacts with the carbon, creating a gas and reducing the carbon content of the metal.

In doing so it superheats the molten metal to white-hot temperatures, which generations of steel workers had to endure, as depicted in these films. They still do. Iron ore is the second most valuable traded commodity in the world after oil, and 90 per cent of all metal used each year is steel. Most of it is still made the same way, by blasting oxygen through enormous buckets of white-hot liquid metal.

Steel (1945)

Steel (1945)

The steelmaking process documented in these films seems rudimentary, brutal and raw. But this is because the subtleties that make the material revolutionary are hidden from view inside the metal itself. The steel created is not just a grey blob of matter; it is, in fact, made up of billions of tiny crystals. Each one has a highly controlled chemical composition and structure.

The films show how the metal is laboriously worked into sheets and rods, but throughout this process its crystals do not shatter under the duress. Instead, they change shape and their internal structure is transformed. Obtaining these structural changes is the purpose of the rolling and forging shown in the films; it imparts the high strength and toughness that is the hallmark of steel.

It is the properties of these forged-steel crystal structures that make the material ideal for almost every type of engineering on the planet. So, although the industrial scenes depicted seem to portray a primitive technology, in reality they are a record of progress: literally the white heat of technology.

That steel is celebrated using celluloid, a material that created the new visual culture of cinema itself, is entirely appropriate. After all, steel is often perceived as monolithic and bland, and needs its exotic cousin to bring out its magic.

This article appears in the sleeve notes for the BFI DVD This Working Life: Steel, released on 18 February.

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