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The History of Ball Clay Production

Over the centuries there has been an evolution in the methods used to extract the valuable seams of ball clay. The methods varied slightly between the three areas of production. They are summarised below and then described in more detail.

Shallow trenches - from the 1600s
Small open pits - the natural development of shallow trenches, which grew in size when pumping techniques improved in the 19th century.
Square pits - a development of small open pits in South Devon, enabling clays to be worked at a greater depth
Shaft mining (underground) - widely adopted from the second half of the 19th century
Inclined shafts (underground) - a variant of shaft mining adopted in North Devon from the end of the 19th century until the 1960s
Adit or Inclined tunnel mining (underground) - came into use in the1930s and adopted in place of most shaft mining from the 1950s to the 1990s
Large scale opencast working - progressively replaced all underground mining during the second half of the 20th century: the only method after 1999.

Cross section showing dip of clay sequence and methods of working

The tenant farmers who first found clay under their fields dug it with whatever farm implements came to hand. As time went by special techniques and tools were developed to work the clay. Despite some local variations, they were broadly similar in each of the three production areas.

The basic system was to dig a shallow trench. After removing unwanted overlying material called 'overburden' (or 'head' or 'ridding'), the 'claycutters' cut the exposed floor of clean plastic clay into a criss-cross pattern of 9 inch (23 cm) squares using heavy iron spades with 4 inch (10 cm) wide blades known as 'thirting' (or 'thwirting') irons. (These specialised tools are pictured right). Following this, another claycutter used a weighty, ash-handled tool like a wide-bladed pick or mattock called a 'lumper' to undercut each square to a depth of 9 inches (23 cm) and lever out the resultant cube of clay weighing about 36lbs (16.3 kilos): 70 balls made a 'tally' of 221/2 hundredweight (1.14 tonnes). The claycutters dipped their tools into a bucket of water to lubricate the cutting. A tool called a 'poge' - a curved iron spike set into a stout pole - was then used to pitch the cubes up the stepped sides of the pit to the surface and onto a packhorse or cart. A lighter version of the lumper known as a 'tubil' or 'tubal' was used to trim the working. In this way the whole floor area was removed to reveal the next layer for extraction.



Thirting iron - click on the image to see a larger picture of the tools.
Thirting iron - Spade used to cut vertical sides of
ball clay cube.
Length: 5ft (153 cm)
Weight: 10 lbs (4.5 kg)

Lumper - click on the image to see a larger picture of the tools.
Lumper - used to undercut ball clay cubes.
Length: 3ft 7in (110cm)
Weight 16lbs (7.25kg)

Tubil - click on the image to see a larger picture of the tools.
Tubil - Used to cut clay underground and trim workings.
Length: 3 ft (90 cm)
Weight: 7 lbs (3.2 kg)

Poge - click on the image to see a larger picture of the tools.
Poge - Used to move ball clay cubes.
Length: 3ft 4ins (102 cm)
Weight: 1 lb (0.45 kg)