Brickfield
[2] Historically, the topsoil was typically removed and the clay beneath was stripped and mixed with chalk and ash to make bricks.
In pre-19th-century England, [i]n most areas the brickfield owner hired a brickmaster at a price per thousand bricks to superintend the site and take full responsibility for the output of the operations.
This period coincided with the housing and railway boom in London and cheap river-transport in Thames sailing barges.
All this solid geology is covered with a layer of brown structureless loam (Head), and muds deposited by the rivers.
[6]: 12 Taking the parish of Frindsbury as a referenced example: about 1 foot (0.30 m) of acidic topsoil covers about 6 feet (1.8 m) of head, which lies on the alkaline Thanet Sands.
The head, or clay was now dug from the field in winter by workers (diggers) on piecework rates.
A horse pulled a centrally pivoted beam with rakes that broke up the weathered clay and mixed it into a slurry.
The surface of the porous yellow stock, reacted chemically with the sulphur dioxide in the polluted air to form an impermeable glaze as well as an attractive colour.
[6] When the liquid slurry was ready it was 'laundered' along wooden pipes into square washbacks, the water seeped away leaving a stiff clay mix .
The pugmill had an inlet hopper, and moved the clay mix along a six-foot tube using an Archimedes screw.
[6] The gang consisted of a 'temperer', who cut the clay out of the washback and loaded it into a wheeled barrow, and took it to the berth where he emptied it into the hopper.
A cowl was a stack of 750 'white bricks' laid on edge, and about 6 inches (15 cm) apart leaving channels for the fuel.
It was made in winter by 'scrying' sifting out the half burnt coal from domestic rubbish which had been retrieved from London by barge, then left to rot for a year or so.
The downdraught kiln was circular and about 15 ft in diameter; the hot gases rose but were deflected back down onto the bricks.
There was always an empty kiln ready to take fresh green bricks so production was not interrupted by waiting for a firing to be completed.
The next development was the Long Continuous Kiln where bricks were stacked on flat wagons which were slowly passed through a chamber where hot gases could circulate around them.
