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Geophysics surveys
Geological survey Downley Common
Archaeology of Downley Common - photos
Downley School excavation
Bricks and brick-making
Events next in the programme
Art and archaeology on Downley Common
Poetry at Downley School
Maps and archaeology
The 'Big Dig'
Art workshop on Downley Common
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Bricks and brick-making
Location: Buckinghamshire
The visit to Matthews Brickyard at Bellingdon was arranged to help in the part of the project which is attempting to locate the 18th century brick kiln. The visit would enable the team to have a better idea of how bricks are made using the traditional methods that were in practice at the time of our kiln - a method which is still producing excellent quality bricks today!
Sally (Matthews) led us round and provided us with superb information. She informed us that the kilns in use during the 1700s were very small and it is likely that most of the ephemeral buildings would not survive into the archaeological record. The type of kiln at Downley is likely to have been a simple beehive type.
On our tour round she showed us a large bucket which was used to dig out the clay from the pits in the long-distant past. These buckets can be of varying sizes; one this big needs a winch to lift it out of the pit. The workers call this process 'winning' the clay.
The clay is then stock-piled and puddled with water before mixing with any other ingredients. Matthews uses Reading Beds (the same as for the Downley kiln) which they call 'brickearth'. This is an industry name and should not be confused with the geological term Brickearth which is a very different clay and a different age - although both are used for brick-making.
Just as at Downley, the Reading Beds is very patchy in its distribution around Bellingdon, which makes prediction of the total reserves very difficult indeed.
The Reading Beds does not have any natural organic material within it which will make for a good firing brick - hence suitable materials have to be added to ensure an even and good firing, and a quality product. The additive at Matthews is known as 'clinker' which is a pulverised coal (similar to that used in power stations).
On extracting the clay the workers suddenly come across very large, irregular flints. They call these 'diamonds'! They are a nuisance to the brick-making industry, but once extracted they can be sold for use in their rough form in garden walls or they can be knapped for other building uses.
Once the clay is extracted and wetted to the right consistency (puddled) it is put onto a conveyor belt to be crushed and worked. Any 'diamonds' not seen and removed beforehand will pop out of the conveyor when pressed by the crushing wheel. Downley may well have had a pug mill for mixing the clay, which would have been worked by a horse. The smoothed and stone-free clay is then sent on to the processing area.
At the processing area the brickmakers take a wedge of clay and work it on the bench, making it into a rough rectangle. The brick mould has some sand in it to stop the clay sticking (like lining a dish with flour when cooking so your pastry does not stick!). The clay is slapped into the mould, rolled in firmly with a 'rolling pin' and then the excess clay cut away with a curved metal tool to leave a flat top to the brick. All these artefacts should be something the team will look out for when/if we need to excavate the kiln area or adjacent pits.
The bricks are placed on a rack and left in a covered location to dry out nice and slowly so that no cracking occurs. When dry, each brick will have lost half a pint of water!
When dry, the bricks are then carefully stacked in the kiln. This job is crucial to the success of the firing. Sometimes the larger loads have to insert a 'dead man'. This is a layer of pre-fired bricks (they are the redder layer in the photograph). This is essential to help the kiln hold the heat in the centre and prevents too many rejects.
Matthews kiln is a Scotch kiln. It was firing during our visit and we were able to look through the peep-hole to see the bricks firing. The amount of air used to ventilate the kiln is controlled very carefully. If it is a windy day, this can become a problem and the kiln will fire too hot. The result are overfired bricks which can be melted and distorted and will form the reject pile. All kilns have reject dumps - where is Downley's?
The most popular brick at the moment for Matthews are the Chalfont Red - a bright red brick. Bricks do go in and out of fashion - a little while ago they did not sell very many of these - now they cannot make enough to satisfy demand! During the 1700s bricks were extremely popular - a very expensive fashionable building material which was only affordable by the very rich elite.
It is interesting to see the different colours of the bricks after firing. They are all made from the same clay, but the colours vary depending on their position in the kiln. Those bricks on the very outside of the pile are a pale orange; those that form the next layer into the pile are the bright reds (the Chalfont Reds here); in the centre the firing goes on for longer and has reached a much higher temperature - these bricks are grey or blue-grey. The blue-greys are the toughest of all the bricks - very strong. If you tap them together they will 'ring' - compare this to the dull 'thud' of average bricks.
Lastly, finishing touches can be put to the edges of bricks in the form of attractively coloured glazes. This is a tricky process to get right and the result is often just a happy accident! The small kiln was operating with a glazing experiment when we visited and the glazed products varied from glossy bright green to a deep blue.
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