Compiled by Daniel Skeffington
About Surface Therapy
The recent TACA membership survey revealed a significant interest in a regular conversation on glazes, not so surprising given the endless variety available to the contemporary clay worker and the plethora of available information. So we will commence our way through the glaze maze, seeking wisdom from experienced practitioners then bringing it to you here online.
I suggest, however, that the word ‘glaze’ is often casually used to describe a ceramic work’s ‘covering’ – that which is added to a raw (or bisqued) clay piece which covers and/or colours the pot. It follows, though, that not all surface coverings are glazes, so in this series we are going to examine not only glazes but also other surface treatments.
Surface Therapy #1: Who is Billie? Why is she so blue?
Dry Glazes – context, history and characteristics
The term ‘dry glazes’ is wrong! That is if one uses the word ‘glaze’ for its conventional meaning. Frank Hamer, the recognised authority of ceramics vernacular, states:
Glaze: A layer of glass which is fused into place on a pottery body. The glaze provides a hygienic covering on pottery because it is smoother than the body it covers and is non-porous. It is also decorative, providing colour, shine and textural contrast …
So where do dry glazes fit here?
Dry glazes are usually composed of a non-glassy formula, so the most prominent qualifiers from Hamer’s definition – “hygienic covering from a smooth shiny non-porous covering” cannot be satisfied for a typical ‘dry glaze’. However, nobody can deny that dry-glazed vessels can be ‘decorative, colourful or textured’ – satisfying the other Hamer glaze criteria. Perhaps we should start referring to them as non-gloss glazes, or, better still, because the word ‘dry’ refers to both a non-glassy surface and also tactile dryness, we might use the description ‘dry surface coverings’.
The scope of ‘dry surface coverings’ is considerable – from slip with a significant proportion of liquid clay, to engobe (which can be a clay layer with or without additives or colourants), to a mixture without clay elements, or even to a formulation of minerals and oxides. The commonality is that they are responsive to the refractory process. Another feature here is the minimal amount of glass and glass-like materials. Often the terms slip, engobe and dry glaze are used interchangeably.