Scotland's Brick and Tile Manufacturing Industry

Graces Guide information.

Graces Guide information.

Below – 1881 – Advert David Colville and Sons Dalzell Steel and Iron Works, Motherwell.

23/02/1940 – Motherwell Times – I see from the February number on “Colvilles Magazine” an interesting article on “Foamed Slag” being a new product devised as a substitute for timber. Extracts from the article read as follows; “The building material is Foamed Slag, a light-weight cellular concrete aggregate produced by special treatment of molten blast-furnace slag, crushed and graded into commercial sizes. This material has been already introduced in England a few years ago with continually increasing popularity. A large plant for Scotland has just lately gone into production, operating in conjunction with Messrs Colville’s blast furnaces in Glasgow. In order to be able to appreciate fully the purpose and importance of this demonstration structure, it is essential to refer, first, to some of the particular properties of this new material which has been thoroughly tested by the Building Research Station and for which just lately a special B.S.S. has been issued.

A particular feature of Foamed Slag is its remarkably low weight. One ton of the coarse (1/2″ – 1/8″) aggregate is equivalent to 3 cubic yds by volume, which enables a 5 ton high sided lorry to carry 15 cubic yds. of aggregate instead of 5 cubic yds. of crushed stone or sand – a fact of no negligible importance in view of the prevailing petrol restrictions.

Another important point in connection with this material is its chemical composition which is identical with that of the raw material of blast furnace Portland cement used in Scotland. This is the reason why Foamed Slag, besides being an aggregate, is also a slow-acting hydraulic agent with ultimate economy in cement. A further feature of Foamed Slag and Foamed Slag concrete is its remarkably high insulating value, which is about four times that of brick and concrete. A Foamed Slag wall of 4″ thickness will thus in this respect be equivalent to 16” brick or concrete wall, and this fact explains why Foamed Slag buildings do not show any traces of condensation. Quite a unique feature of Foamed Slag concrete is the possibility of varying its weight. Whereas ordinary concrete, regardless of the fact whether it is strong or weak, will weigh about 145 lbs. per cubic ft, Foamed Slag concrete can be varied from about 40 lbs. to 120lbs. per cubic ft. with a corresponding crushing strength of 100 – 6000 lbs. per square inch. This great elasticity in its utility explains why many eminent architects and engineers look upon Foamed Slag as the building material of the future.

31/05/1947 – Western Mail – Colvilles Limited  Sir John Craigs statement … We have retained the brickwork producing ordinary building bricks, formerly owned by Archibald Russell. Ltd (Tannochside) and have also acquired Rosehall Brickwork. Both these works are situated in Lanarkshire. The raw material comes from old colliery bings and by their removal we are serving the double purpose of improving the amenities of the district and producing bricks which are so much needed today. During the year, we entered into an arrangement with Messrs. Clugston Cawood. Ltd., and formed a company, Colvilles-Clugston. Ltd. Messrs Clugston have wide experience of dealing with slags and we thought it would be useful to join with them in developing the production and distribution of slag products. Colvilles-Clugston are laying down new plant at the Clyde Iron Works and as soon as it can be brought into operation, we hope it will lead to the disposal of a large quantity of our blast furnace slag …

13/02/1953 – Motherwell Times – Colvilles Limited, Motherwell. Annual meeting. Chairman Sir John Craig … The increasing production of pig iron has brought the question of slag disposal very much into prominence. We have always held the view that all the waste products from our industry should be converted to a useful end and not discarded to create unsightly bings. The practical consequence of this policy saw the formation of Colvilles-Clugston Ltd. to develop uses for our slags. This company, in which we hold a 50 per cent interest, has completed a successful year and is now disposing of substantial tonnages of prepared and graded slag for many civil engineering purposes, where the product is meeting with complete success. Our Research and Development Department has also worked out a new process for the manufacture from slag of a high-class facing brick and orders have been placed for the first unit of plant to gain experience of production on a practical scale. When we are satisfied with the product, these plant units can then be duplicated to take up all the slag available. 

19/02/1954 – Truth – … The chairman’s review indicates considerable progress in development schemes including the erection of a plant for manufacturing facing bricks from blast furnace slag …

03/09/1954 – Motherwell Times – Firms display products at Scottish Industries Exhibition in Glasgow … Colvilles Ltd – The main feature of the stand Messrs Colvilles Ltd., is a model of the proposed development at Ravenscraig. Measuring eleven feet by eight feet, the model itself has been developed since it was shown to pressmen at Dalzell Steelworks recently because it now shows the final development and not the initial stages of the £2om project as originally shown. Round the base of the stand are some slag facing bricks manufactured by the firm at Clyde Iron Works  …

17/01/1955 – The Courier and Advertiser – Colvilles Limited – Share offer … The company owns 50 per cent of the shares in Colvilles – Clugston Limited a company established to develop the commercial application of blast furnace slag … The profitable use of by-products has been the subject of constant research and development, and commercial applications for slag have been found in the production of fertilisers, bricks, road materials and concrete aggregate …

06/09/1957 – Motherwell Times – Notable Extensions At Fullwood Foundry. A new baths building and fettling shop constitute two notable extensions at the Mossend Works of Fullwood Foundry Co. Ltd, which have been brought into commission since the works resumed after the Fair Holiday … The building is galvanised sheeted to within 8 feet of the ground, Colvilles Slag Bricks being used to complete the walls to ground level …

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 autoclave 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 autoclave 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 forklift 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).