What is Naked Raku?
Naked Raku is a derivative of "Western" Raku, which itself is derived from traditional Japanese Raku.
Traditional Raku
Raku has its roots in 16th century Japan. It is a technique which developed within the spirit of the Tea Ceremony, and stays closely tied to this discipline. Tea bowls are extracted from a hot kiln when still glowing. As the glaze on the bowl comes into contact with the cool air (or sometimes with cold water) it quickly drops on temperature, suddenly solidifies and crazes (crackles). Very resistant clays must be used for this technique in order to avoid cracking of the body of the bowl.
Western Raku
Bernard Leach played a major role in the importation of this technique into western ceramics. However it was Paul Soldner and his contemporaries who added the element that would come to distinguish the western version of this technique from the tradition in Japan.
A post-firing reduction was added by simply removing the objects (no longer restricted to tea bowls) from the hot kiln, and placing them into a covered receptacle containing organic matter (dried leaves or grasses, wood shavings, paper, etc.) which upon contact with the hot object would ignite. In this atmosphere deprived of oxygen the combustion produces enormous amounts of volatile carbon which penetrate the cracks in the glaze, or the unglazed areas of the object, blackening them.
Naked Raku
Naked Raku is as the name suggests, naked, meaning that the end result has no glaze on it, just the bare clay surface.
During the drying process the object is polished. There are different ways to get a polished surface on naked clay but the main two practices involve either burnishing with some kind of smooth object (polished stones, light bulbs, old credit/phone cards are popular), or applying a preparation called Terra Sigillata (a preparation of very fine clay particles) and then polishing either with the bare hand or with a very soft cloth or chamois. The piece is then bisque fired to between 900°C and 1000°C. Now comes the element that distinguishes Naked Raku from "western" Raku. Before applying glaze to the piece, a "resist slip" is applied. This slip contains refractory materials, and its job is to stop the glaze from sticking to the piece. The slip/glaze layer can be drawn through with a toothpick or the glaze can be applied not to the entire surface in order to create interesting results (the carbon will pass through the slip layer but not through the vitrified glaze layer). After the firing and the post-firing reduction this slip/glaze layer can be removed like an eggshell. The piece is then washed with plenty of water and a sponge, and a layer of wax applied in order to give extra protection to the surface.
Inspired from a text by Wally Asselberghs