Found in Glasgow by CFA Archaeology Ltd between 2010 and 2011 during archaeological works in advance of the development of the Commonwealth Games Athletic Village at Dalmarnock, Glasgow. The brick was disclaimed by Treasure Trove. Clyde Ironwork Brick Work, Tollcross, Glasgow. . . . .
Article July 1961 – Clay Worker Magazine ? – Colvilles – The brickworks works is situated at the company’s Clyde ironworks, near Glasgow and the material used for their bricks is blast furnace slag. The first bricks they made consisted of 97 per cent slag and 2 1/2 per cent hydrated lime. These were put into an auto clave and steamed for five or six hours but, apparently in the process, the colour was leached out and only grey bricks came out of the oven. As saturation point was soon reached in the popularity for grey in Scotland that company had to turn to colouring their bricks. To do this they reduced the slag content to 87 per cent and added 10 per cent cement bonding and 2 per cent colouring material, consisting of synthetic iron oxide and carbon black. Water makes up the round of 100 per cent. The auto clave was scrapped and the bricks are now hardened in the atmosphere for a minimum period of six weeks. As a result the company have a more saleable brick but they have lost something in quality. The drying shrinkage, for instance is 0.28 per cent and only just manages to meet the specifications whilst one would guess there might be sulphate trouble in time. In addition, the greys are cheaper at £9 per 1,000
Manufacturing Process – The slag is first put into pits and allowed to cool. From here it is loaded into a hopper and fed by skip hoist (about 160 tons a day) to storage bins in the making shop. Other bins cement and colouring which with the slag (ground and turned to dust) are drawn from their respective hoppers and batch weighed. Water is added and the material is mixed in an August Simpson mixer, which used to have rolls but now has a series of paddles. A rotary feeder conveys the mixture to the Hercules presses where a pressure of 120 tons is exerted. There are three presses, each has twelve moulds and can produce 1800 bricks per hour and from here the bricks are carried by fork lift truck to the curing shed.
The colour range of the bricks is now red, brown, yellow and sun buff as well as grey….(there is more but the print is too faint to read)
1915 – David Colville & Sons (thereafter Colvilles) took over Clyde Ironworks.
Below – 1859 – Map Clyde Fireclay Works.
Below – 1934 – Map Clyde Fireclay Works.