Ceramics - How it's made | Ceramic Tiles

 

MAKING THE "BODY SLIP" 

The first problem confronting the tile manufacturer is that of making an intimate mixture of proper proportions of the "body" materials above described. To facilitate this operation they are severally – clays, flint, and stone alike – brought to the condition of creamy liquids – or rather that of finely divided particles suspended in water. In the case of the two clays this is simple enough. Each is placed in a "blunger" – i.e., a hexagonal tub or vat in which powerful arms revolve continuously on a vertical shaft – and slowly churned up with water to a suitable consistency. Flint presents certain initial difficulties, but 
these are overcome by putting this extremely hard and dark-coloured material into a special kiln and calcining it – reducing it – that is, by the action of fire, to a friable substance of snowy whiteness. That done, it is placed, with a liberal allowance of water, into a large stone-lined iron cylinder, and ground to almost microscopic fineness by the action of a heavy charge of uncalcined sea-shore flints, which slide and tumble down the rising side of the cylinder as it revolves. The last of our materials, Cornish Stone, is also hard, but is brought down to the required condition by being first passed through a crushing mill which reduces it to small fragments, and thereafter ground in precisely the same way as flint. 

 

Where Flint and Cornish Stone are ground

Making the desired mixture is now a simple matter. Carefully determined proportions of the four ingredients are run into a large central vat – the "mixing ark "– in which powerful "agitators" mix them thoroughly together. The mixture thus formed, known as "slip" or "body slip," is next passed through "lawns" or sieves of extremely fine mesh – some 20,000 holes to the square inch – and then over a bed of powerful electro magnets, by which latter any particles of iron – which would be liable to cause dark specks in the finished tiles – are extracted. From the magnet bed the slip flows into the "finished 
ark," where further agitators are at work to keep the mixture homogeneous by preventing the heavier materials from settling to the bottom.

A slip-house. Magneting the slip.

 

previous: body materials - where they come from
next: filter-pressing and grinding

From: "A Century of Progress 1837-1937" a publication to commemorate The Centenary of Richards Tiles Ltd.