People and their collections

Robert Plot 1640-96 - scientist & antiquary

Plot and pottery (4): the making of slip in Staffordshire

In The Natural History of Stafford-shire (1686), Plot describes potting clays in Burslem (Stoke-on-Trent), Staffordshire which could be worked on the wheel. He then goes on (p 122) to explain about slip clays:

' Which none of the three other clays, they call Slips, will any of them doe [i.e. work on the wheel], being of looser and more friable natures: these mixed with water they make into a consistence thinner than a Syrup, so that being put into a bucket it will run out through a Quill, this they call Slip, and is the substance wherewith they paint their wares; whereof the

1. Sort is called the Orange Slip, which before it is work't, is of a greyish colour mixt with orange balls, and gives the ware (when annealed) an orange colour

2. The white Slip, this before it is work't, is of a dark blewish colour, yet makes the ware yellow, which being the lightest colour they make any of, they call it (as they did the clay above) the white Slip.

3. The red Slip, made of a dirty reddish clay, which gives wares a black colour.' (Plot 1686 p122).

Plot here explains how the slips appear under a coating of glaze. The wares which had slips applied to them included: slipwares, yellow wares and slip-coated blackwares. They were once-fired, that is, they were thrown, allowed to airdry, perhaps slip-coated or slip-decorated, and then glaze added, after which they were fired. The orange, red and white slips are actually those colours when the glaze is absent. As well as being expertly utilised for decoration, slip was also used to disguise the body. So, for example, slip-coated blackwares have a pale, buff-firing body, which was coated with red slip exactly where the glaze lay, so producing a black-glazed vessel.

North Staffordshire pottery with coloured slips, with and without glaze

Clays used for potting

Plot and Pottery

Preparation of clay for potting