Between the realms of Clay and Glaze lies a continuum of mixtures that exhibit properties of both to some extent. The chart below (Barringer: Studio Potter; 12/95) lays out a general way to describe these mixtures, but the terms and properties are by no means rigid. The literature varies on this subject, as does practice at CAW – where they are all labeled either: Slips for Greenware or Slips for Bisque.
- Strictly speaking, slips are mixtures of clay and water blended to a creamy consistency, possibly with a colorant added. They have to be used on wet or damp clay only or else they will crack as they dry and shrink. Terra Sigillata (an earthenware application) also belongs at this end of the chart since it only contains clay, deflocculant, and sometimes colorants. The sheen of terra sigillata results from the fine particle size of the platelets and physical polishing.
- Englobes are similar, but with relatively less clay, they contain fluxes and colorants to behave more toward a glaze, can be used on bisque, and will often fire to a matte finish.
- Vitreous Englobes are englobes with a still higher proportion of glaze ingredients, intended for bisque application, and may be used in lieu of a glaze to provide an impermeable surface.
- Slip glazes are clays that will form a glaze at stoneware temperatures without any additional flux. These are useful in making once-fire ware.
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