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CHANCES ARE, most people have heard of the name Perspex and have probably used it both figuratively and literally in reference to many different clear plastic products.
It seems Perspex has become one of the UK's ubiquitous brands as well as being one of the most widely used terms for plastics. In fact, the word Perspex came into the English language in 1934. Derived from the Latin "to see through," it was registered as the trademark for ICI's acrylic sheet. The product began life as a general study of polymeric materials and as a project to find a laminated safety glass interlayer but before volume production was possible, two very different projects were combined to create and commercialise the clear Perspex sheet.
John Crawford of the research department at ICI wanted to find a replacement for cellulose nitrate, which yellowed badly in sunlight while Crawford Hill of British Dyestuffs had prepared the polymer of methyl methacrylate which turned out to be unexpectedly hard and tough.
Monomer to market
The unique properties of the material were recognised from the start, but it was also apparent that an economic route to the monomer was required before commercial production was possible. Crawford's contribution was to determine the conditions necessary to achieve an optimum yield. This work resulted in a process that could produce 100lb batches of methyl methacrylate monomer that appeared commercially attractive. Produced in Billingham at the Cassel Works, the monomer was cast between flat sheets of glass separated by a gasket and polymerized in an oven. This process still forms the basis for the commercial manufacture of acrylic throughout the world, albeit more stable with greater quality control and larger volumes.
Originally produced as a replacement for safety glass, where it offered a weight saving, the war inspired significant demand for Perspex as a glazing material for aircraft. With this increased demand, the Ministry of Supply insisted on manufacture over a number of sites to minimise the risk from enemy attack. A production site at Darwen, Lancashire was found and in 1940, production of Perspex began on a small scale and continues to this day.
The fledgling product soon became an important part of the war effort, with 50 tons of Perspex produced during that first year at Darwen for the cockpit canopies of fighter aircraft. In the Battle of Britain year, production had increased to 455 tons and by 1944 Perspex had grown to six thousand tons.
As expected, with the end of the war, the need for Perspex fell to less than half the wartime peak. Succession planning for the product had been considered however, and a corrugated Perspex sheet was produced to allow natural daylight into buildings, specifically for industry and agriculture. Favourable reports on its performance meant the product became a success but it took longer for Perspex flat sheet, both clear and coloured, to find a replacement market for the capacity that had been developed during those war years.
Sign of the times
One of the colours developed at Darwen was opal, in four different grades, which helped to create a demand in an entirely new market - for indoor and outdoor lighting applications. Endorsement of Perspex for the lighting industry was helped by a significant installation of four hundred fittings designed by Sir Gilbert Scott for the new House of Commons. This success and the abundance of grades and colours subsequently lead to the consideration of Perspex for signs and fascias.
Complemented in no small part by the characteristics of the material, signage remains a market of prime importance to this day.
With its high molecular weight, Perspex cast acrylic benefits from excellent strength, rigidity and resistance to weathering, making it suitable for use both indoors and outdoors. A versatile material noted for its clarity and produced in a batch process, Perspex offers the flexibility for many colours, surface textures and grades. Available in a range of standard products from UK distributor, Perspex Distribution, and with an accumulated store of colour-match records, Perspex has been used for many innovative sign applications and corporate identity programmes.
Notable for its landmark status off the M6 at Birmingham, the Fort Dunlop sign is a great example. Produced by ASG, the sign uses the latest Perspex Opal LED light source grade and has been recognised by industry as Sign of the Year. Built of individual letters, each standing 2.5m high, the Hollywood style sign spans 45m in length.
Supplied by Perspex Distribution, branch manager in the Midlands, Paul Neal, said: "This spectacular sign at the summit of the Fort Dunlop building is made more impressive by the number and combination of colours that can be produced, with a brilliant and even illumination through the specially developed Perspex surface."
Now, 75 years after it first appeared, Perspex is produced in many variants and for many applications. Supplied in the UK since 2003 by Perspex Distribution, Perspex cast acrylic is a clear example of a UK made product that is flourishing. One of the UK's foremost plastics products, today Perspex is as much about colour as it is about clarity with no sign of the brand falling out of vogue.