Look from the past - Traditional brick manufacturing methods

Clay Technology magazine
,
1 Dec 2007

Advances in technology have led to cheaper and more efficient manufacturing techniques, yet handmade bricks are still popular for aesthetic reasons. Several factors differentiate them from machine bricks, including forming, setting, firing and blending.

The moulds in which handmade bricks are formed are inherently flexible. This means that a brick can be manufactured in virtually any size, from 300x135x90mm to 40x100x50mm (briquette), depending on the type of clay.

In the beginning

The history of brickwork, as detailed in books from Nicholas Pevsner to Nathaniel Lloyd, in his History of English Brickwork, highlights the huge variety of sizes and formats used over the centuries. This is one reason why handmade is different, offering more flexibility for conservation or consistency purposes. Texture also plays a role, varying from smooth, exemplified by the famous Williamson Cliff range used on Oxbridge Colleges and Buckingham Palace, to a rougher brick. The smoothness or weathered look can be affected by the dampness in the sand and speed at which the bricks are manufactured.

A traditional bench-made handmade brick produced individually means it would be hard to make more than 1,000 bricks per man, per day. The maker has to sand the mould by hand, prepare the clay and throw it into the mould, cut off the surplus with a bow and turn the mould over, emptying it onto a tray for drying. This slow operation means you would be lucky to make 100 bricks an hour. However, the bricks are neat and tidy and have arrises at least as good as a machine-made brick. A mechanised hand thrown system known as a circuit – where the maker throws the clay into the mould and the machine does the rest – enables output up to 30,000 per day with a five-man team. The bricks are more distressed and rougher looking, although the colour and effect can be attractive.

Back to basics

To understand the aesthetics and originality of the bricks, one of the basic aspects of production, the setting pattern in the kiln, must be considered. To create a traditional handmade clamp look, which many conservators or new home builders are trying to replicate, a mechanised setting machine or robot cannot be used, as they do not produce the necessary variations in colour. Instead, the bricks must be packed in a dense pack so the fire does not go evenly through the bricks. Nevertheless, in a modern intermittent kiln, firing, if not the colour, can be made consistent, not something possible in the clamp fired bricks of old.

The right mix

When the bricks come out of the kiln it is important that they are blended because the middle of a dense pack of bricks will be a different colour to that on the outside – due to the difference between reduction and oxidisation.

A particular building or client may require a dark, weathered look but with red or pink parts. This can be achieved by putting part of the colour pallet into the sorting system, ensuring a random mix of colour around the pack, or manual mixing. The benefit of this method is that additional care onsite is not required. This advantage in productivity is more important than ever on building sites. The result is a brick wall that appears more alive and interesting than one made by a modern machine. Every clay building has its own appeal, but handmade bricks offer a traditional look from the start.

In the production of specials for use with handmade bricks, it is important to remember that they can be more easily manufactured than those for machine-made brickwork. This requires a mould and a knowledgeable operative to enable all types of shapes to be made in a fairly economic manner.

 

Further information:

David Armitage, York Handmade Brick Company, Forest Lane, Alne, York, North Yorkshire, YO61 1TU, tel: +44 (0)1347 837202, Email: darmitage@yorkhandmade.co.uk.