Fred Starr recollects – the romance of brickmaking
Fred Starr recollects.
What a terrific story Mary Lawson FIMMM had to tell in Materials World, August 2019 (page 33). At the start of WWII, when government planning was not just public relations spin, she was directed to work in the engineering branch of the BBC. With the dawning of peace, and newly married, she found herself in Scotland at a branch of the Building Research Station, in charge of a section dealing with the properties of bricks, concrete, pipes and tiles.
Despite the tremendous pressures women then faced, Mary made a career while bringing up a family of four. I was impressed with how she played the Civil Service rulebook to get a house for her family – maybe Mary should have been running the Brexit negotiations.
What Mary had to say about Scottish building bricks set me thinking of my home town of Stockton on Tees. Its 19th Century working class terraces were built with greyish, salt layered bricks. Could they have been made from the tailings of the coal mines up in Durham, containing enough coal to be self-fired, as she described? By 1935, every new house in Stockton was red brick, made from the extensive deposits of boulder clay that lay around the lower Tees.
What also disappeared about the same time was the local method of paving streets with what appeared to be granite setts. This Teesside 19th Century innovation is periodically reinvented as a method of making better ceramics. Streets on Teesside were laid with Scoria bricks, which in the upmarket neighbourhoods were imprinted with an artistic pattern. Scoria – a local name for blast furnace slag – was remelted and cast into brick-like shapes. Not very original, you might think.
The real breakthrough, which must have been serendipitous, was that an ageing treatment at moderate temperatures greatly improved brick toughness - vital for road bricks when wagon tyres were steel. During heating, the glassy slag turned crystalline, the multiplicity of grain boundaries, boosting fracture toughness. In 1964, the British Iron and Steel Research Association rediscovered the idea, seeding blast furnace slag with titania, calling the material slag-ceram.
Work was carried out on the site where the now defunct Redcar blast furnace still stands. Ken Goodwin and myself were used as labourers and in one of our sandwich course industrial periods, down from Battersea College. I became skilled in the use of a pneumatic drill, every morning starting with the need to break apart the solidified slag from the previous day’s experiments. Like many initiatives, slag-ceram died in this country but it lives on in Turkey, if, as a materials anorak, you want your bathroom tiled in blast furnace slag.
Smashing lessons for a budding scientist
Stockton bricks came from a huge clay pit belonging to Blacketts Brickworks. There, just at the end of our street, the pit stretched for hundreds of metres, on two levels – the early workings at a depth of 15m, the later ones getting down to about 30m.
The soft clay was dug out by an excavator, loaded into trucks, which were attached to an endless cableway that hauled them up a long incline, on a 2ft gauge railway, to the brickmaking works.
To us it was the most wonderful adventure playground. To the owners, we were childhood hooligans. Nevertheless, it was in Blackett’s where I began to get a rudimentary grasp of Newton’s three laws of motion. I comprehended that the best way of bringing about the most spectacular crash of the bogies, as we called the trucks, was to release one of them from the highest point possible on the incline. The bogie was then running at maximum velocity before collision occurred.
Nature knows best
My sketch dates from the 1970s, just before the whole site was permanently obliterated. Its end was indubitably poignant. Nothing now remains, just low mounds, where the brick moulding sheds and kilns once stood. The pit lies beneath a featureless grass field, ironically filled in with bricks from local slum clearances.
Materials World often writes about the need to reclaim disused mining and industrial sites. I wonder if the wholesale covering up of past industrial endeavours is always sensible. Given time, nature would have repopulated Blacketts, filling the canyon-like pit with flowers, bushes and saplings, and swathed the old buildings with ivy. It would have happened. I knew of a tree-lined lovers’ valley between the River Tees and the Malleable Steelworks, that was once itself a clay pit. It too has vanished, replaced by a golf course.