David Roberts' Coiled Raku
Ceramics Monthly, December 1990, pp22-25
The first David Roberts pot I saw was in the home of collector Alan Firth. It was a large bowl with bluish white glaze, much crazed. I was somewhat disbelieving when told it was raku ware. Raku? Surely not! The characteristics of this pot were control and harmony between glaze and body.
All right, so here was a potter with expertise in throwing large, thin bowls. Wrong again. I was told it was coiled. Indeed, on closer inspection it clearly could not have been thrown, though its symmetry was better than many wheel-made works of its size. And it was so large for raku. My experience of this process was of “frozen fire” surfaces – lustrous, brightly colored on pots that were more often small and usually thick.
I remembered the pot, and the potter’s name, and hoped to see more. This must have been about 1980. By then, Roberts had already established a pattern of working and a reputation as a consistent and serious potter, when so much of the work that was making the rounds was experimental or frivolous. In the years since, he has been a leading influence in the popularizing of raku.
Roberts was horn in Sheffield, England, in 1947. Twenty years later he gave up working in an engineering factory to enter a teachers' training college – Bretton Hall near Huddersfield – that specialized in the arts. Like many others, he wanted to be a painter, but expected to become a teacher. His first contact with clay was not a happy one – finding it intractable stuff and unappealing. But gradually, as his control of the material improved, he grew to like it.
By the time he left college in 1970, to teach in a large comprehensive school, Roberts was absorbed by pottcry, principally making thrown stoneware. Soon after, a turning point came when Jim Robison came to live near him in Holmfirth, and showed him slides of American potters making large-sized raku pots as unlike Oriental teabowls as can he imagined. The American influence on Roberts was immediate. He had found the raku technique boring after seeing it demonstrated in the traditional Oriental way, but in the hands of artists such as Paul Soldner, he saw raku as a route to a monumental and sculptural form of ceramics.
Discarding the mystique of raku, Roberts retained only its most basic elements. Pots bisque fired to a shade over 1800F (1000C) are refired with glaze to about 1740F (950C), slowly cooled to 1560F (850C), then abruptly removed from the kiln to be reduced in sawdust or straw.
The constraint on size of traditional raku had not be the impossibility of keeping apot over a certain size in one piece during cooling, but the size of the kiln’s firing chamber. Roberts’s approach was to create a spacious kiln that could be removed from the pot, instead of vice-versa.
The top-hat or clamp kiln is ideally suited to raku since it simplifies the problem of hoisting pots out of a red-hot environment, and it is the key to Roberts’s development. Following plans from the magazine article, he built a first kiln out of two oil drums lined with the then revolutionary ceramic fiber – Kaowool blanket – which combined lightness with insulation. He could hoist this lightweight canister away from the fired pot by a simple pulley simple pulley system, using a bucket of water as a counterweight. The source of heat was first one then two propane burners. His large insulated metal-can kiln would reach an internal temperature of 1800F in about an hour. Roberts could have packed his oil-drum kiln with lots of glazed bisque-ware, but instead he maximized the size of pot it could take, and in this way started to treat ceramics as a sculptor might: each work is given the full attention of its own firing.
By rigidly sticking to this routine, and by using the latest materials and techniques, Roberts has made raku work for him. To withstand thermal shock – the pot goes from bisque-cold to glazed and cold again in a mere two hours – he uses a white stoneware body with a low coefficient of expansion, and with added grog to keep the clay open. His first firing to bisque, just about 1800F, is done nowadays in a conventional electric kiln, and the original oil-drum kiln has been replaced by two larger, similar top-hat kilns – one with a tall firing chamber for vases, the other shallower for bowls.
For glazes, he avoids lead (even lead frits) because of the potential toxicity associated with crazed low-temperature ware, and instead uses soft borax and high-alkaline frits, with kaolin as a stiffener plus tin oxide to give whites.
It is well known that lustrous surfaces and bright colors, particularly reds, are achievable in raku ware, but Roberts has to date concentrated on the dark blue-grays of carbonization under white glazes, rather than using the oxides that give heightened color.
The peephole in the kiln is vital to a man of stop-watch precision, who leaves as little as possible to chance. After the work receives a short glaze-soak at 1740F, the top part of the kiln is removed when the temperature has fallen to 1560F – still red-hot. Roberts counts the seconds before locking tongs around the huge pot and transferring it to a reduction chamber where sawdust or straw, in contact with the molten glaze, burns.
Starved of oxygen (as the reduction chamber is sealed with a lid), carbonization takes place through the glaze, darkening and discoloring the clay especially around the crackled network that has formed through the rapidly cooling glaze.
Once the temperature has fallen inside the surrounding sawdust chamber to handleable levels, the pot is removed, hosed down and scrubbed clean. A fine secondary reticulation of' crazing appears as the pot cools, giving the pot surface an apparent extra depth.
It is an exciting hour or so when the potter swiftly and minutely controls the final surface and its patterning by the thoughtful arrangement of sawdust on and around it in the cooling stage. For Roberts, there are no happy accidents. Unsatisfactory pots are discarded. It is only to be expected that in raku ware there would he a high failure rate. Between 10% and 50% are lost, a fact he accepts and expects will remain the same.
So much for technique, its pitfalls and Roberts’s uncompromising method of tackling it. Now what of the pots themselves?
When dealing with large and extra-large pots, the form is very revealing. Only on small pots can superlative glaze make up for an uninteresting shape, and Roberts is adamant that form is the most important aspect of his work.
By coiling, using extruded coils for uniformity and speed, he has chosen an unusual route to the classical forms that he favors. Technically, coils are appropriate since the pots are made by compression and do not have the tendency to spiral fracture that raku firing induces in some wheel-thrown ware, but most coil builders look to organic shapes and organic symmetry rather than mathematical precision and bilateral symmetry. By rotating the pots on a banding wheel as he builds them, Roberts achieves with the aid of a metal kidney very regular shapes indeed.
His shallow howls are frequently feathered at their rims to a fine edge, kept clean of glaze, incidentally, by tape resist when the glaze is sprayed on. Sometimes on the inside there will be a cusp or edge, marking a change of' glaze or surface texture. The howls are huge: if many potters’ howls are the size of a hubcap, these are as big as the spare tire on a Bentley.
The bulbous bottle forms, for which Roberts is best known, have such a tight surface that they seem almost at bursting point, and they carry a variety of flanged rims or necks, as well as lugs. In these pots can clearly be seen the influence of African coiled ware and the beautiful eggshell-like pots of the Pueblo Indians of North America. Roberts acknowledges Mimbres ware and its decoration as source material.
A third category of pots has a trumpetlike neck emerging from the bulbous base with a carefully placed dividing line keeping two different glazes apart. I personally find these taller shapes still unresolved, as if they are halfway stages in the progress toward a new form.
To summarize, David Roberts has grown up in a more favorable climate toward artist-potters than has existed before this century. In this climate a great many self-indulgent potters of his own generation have achieved prominence based on their nose for fashion or their skill at ceramic parody. A few have excelled in the handling of the newly fashionable salt-glaze techniques exhumed from obscurity, as with raku in the 1970s and 1980s. Yet he has created a personal and recognizable style, combining somewhat contradictory features – an organic technique (coiling) to achieve classical and symmetrical forms; a firing process, traditionally inimical toward large pots, to produce ware with an exactly finished glaze. Art school teachers, certainly those of a less adventurous age, would have told him, had he been their student, not to d it because it would not work. But he has done it, and it does.