Ceramics - How it's made | Ceramic Tiles

 

FIRING THE GREEN WARE 

We have now to consider the firing of the different wares that have been made. Until about  a quarter of a century ago all pottery firing was done on the "intermittent" principle, usually in the large bottle-shaped ovens which give the "Five Towns" so characteristic an appearance.  The oven having been filled with ware, its fires were kindled, maintained for the necessary time, and allowed to die out. Now, however, "continuous" firing is firmly established and rapidly becoming more general. In this system the oven or kiln, commonly in the form of a long, straight tunnel, is kept constantly at firing temperature, and an unbroken stream of ware-laden fireclay trucks moves continuously through it, the construction of the kiln interior and of the trucks being such that there is no excessive heating of the trucks' iron bogeys or of the rails on which they run. 

To discuss the relative merits of these two systems is beyond the scope of the present booklet. 
Suffice it to say that at the Brownhills factory – which is devoted almost entirely to the production of white glazed tiles – we use only the continuous method, while at the parent plant, with its greater diversity of products, both systems are in operation, improved types of bottle-shaped ovens being used for the firing of "green" ware, and continuous kilns for the firing-on of the glaze – a subject with which we shall deal later. 

Overhead conveyors at Pinnox Works....

...forming a traffic highway 2,300 feet long.

 

By whichever method they are to be fired, the green tiles, "Recesso" fittings, or faience pieces are first of all placed in " saggars "– receptacles which might be mistaken for crude pie-dishes from a giant's kitchen – made from local fireclay. If, as is suggested, the name "saggar" is a corruption of "safeguard," it indicates their primary object, which is to protect their contents during firing from direct 
contact with the flames by which they are surrounded. Let us follow some charged saggars through the particular firing process suited to their contents – some saggars of wall tiles, let us say, to be passed through a tunnel kiln, and some of floor tiles or mosaics, to be fired in an up-to-date bottle oven. 

Some modern 'bottle' ovens at Pinnox works

 

previous: hand-making Faience
next: firing the green ware (2)

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