Joining and molding An additive with
deflocculant properties, such as
sodium silicate, can be added to disperse the raw material particles. This allows a higher solids content to be used, or allows a fluid to be produced with a minimal amount of water so that drying shrinkage is minimised, which is important during
slipcasting. Usually the mixing of slip is undertaken in a
blunger although it can be done using other types of mixers or even by hand. • To join sections of unfired ware or
greenware, such as handles and spouts. • To fix into place pieces of
relief decoration produced separately, for example by
moulding. This technique is known as
sprigging; an example is
Jasperware. • When slip is used to join two pieces of greenware together, it is generally used with a technique known as scratch and slip, whereby the contact points on both pieces are scored with multiple criss-crossing lines and slip painted on one piece over the scores.
Decoration and protection , English, c. 1685. The plate's diameter is 43 cm; such large plates, for display rather than use, take slip-trailing to an extreme, building up lattices of thick trails of slip. sugar bowl with combed, slip-marbled decoration, c. 1795
Slipware is pottery decorated by slip placed onto a wet or
leather-hard clay body surface by dipping, painting or splashing. Some slips will also give decreased permeability, though not as much as a
ceramic glaze would give. Often only pottery where the slip creates patterns or images will be described as slipware, as opposed to the many types where a plain slip is applied to the whole body, for example most fine wares in
Ancient Roman pottery, such as
African red slip ware (note: "slip ware" not "slipware"). Decorative slips may be a different colour than the underlying clay body or offer other decorative qualities such as a shiny surface. Selectively applying layers of colored slips can create the effect of a painted ceramic, such as in the
black-figure or
red-figure pottery styles of
Ancient Greek pottery. Slip decoration is an ancient technique in
Chinese pottery also, used to cover whole vessels over 4,000 years ago. Principal techniques include slip-painting, where the slip is treated like paint and used to create a design with brushes or other implements, and slip-trailing, where the slip, usually rather thick, is dripped onto the body. Slip-trailed wares, especially if Early Modern English, are called
slipware. Chinese pottery also used techniques where patterns, images or calligraphy were created as part-dried slip was cut away to reveal a lower layer of slip or the main clay body in a contrasting colour. The latter of these is called the "cut-glaze" technique. Slipware may be carved or burnished to change the surface appearance of the ware. Specialized slip recipes may be applied to
biscuit ware and then refired.
Barbotine (another French word for slip) covers different techniques in English, but in the sense used of late 19th-century
art pottery is a technique for painting wares in polychrome slips to make painting-like images on pottery.
Other uses in pottery A slip may be made for various other purposes in the production and decoration of ceramics, such as slip can be used to mix the constituents of a clay body. ==Gallery ==