An Investigation into the Properties of Porcelain Paperclay
by Gaye Stevens

Originally published in Ceramics Technical. Reprinted by permission.

In July, 2000, I began a research project with the assistance of a Faculty Research Grant from The College of Fine Arts,University of New South Wales to investigate the properties and potential of porcelain paperclay.

My studio work is concerned with the vulnerability of being human, with the dynamics of how we interact as a community and the consequent processes of acceptance and rejection. Hence, the juxtaposition of light and shadow has held significance for me as a metaphor for inclusion and exclusion. I have been searching for a medium that will convey fragility and vulnerability but one that also has a degree of permanence. In early 2000 I had read an article by Steve Harrison ‘The making of paperclay porcelain banners’ (Pottery in Australia 37/2 1998 p68-69). In this article, Harrison describes how he makes paper-thin porcelain banners of translucency that can be imprinted with "tools fingers and objects".

It seemed that this medium had potential for the type of sculpture I wanted to produce. My aims were twofold. Firstly, I wanted to find a way of imprinting thin sheets of this body with a photographic image to produce a watermarked effect. That is, I wanted to find a way (without using any ink), of pressing a photographic image into the clay body, using some appropriate kind of intaglio printing plate, in order to yield a heavily embossed image which when backlit, would produce a photographic watermark. Secondly, I wanted to explore the potential of this body for producing 3D forms that would lend themselves to illumination.

My starting point was his recipe for porcelain paperclay :

The clay body is fired to cone 8 in an electric kiln.

The ceramic fibre helps to stabilize the body after the paper pulp has burnt out at 250ºC and stops the thin sheets from cracking "along the stress lines created by the decoration".

The initial process of familiarizing myself with porcelain paperclay body proved to be not as straightforward as I anticipated. The result of my first batch was coarse textured and short, totally inappropriate for holding the imprint of a recognizable photographic image.

To produce a finer textured body I used shredded ceramic fibre (rather than ceramic blanket which I had used initially, that had to be laboriously torn into tiny pieces) and mixed it with a heavy-duty blunger in about four liters of water, until satisfied with its homogeneous consistency. I mixed the paper pulp in a similar way and with about the same amount of water, but I used boiling water this time, to help break down the fibres. The ceramic fibre and paper pulp were then thoroughly mixed with the blunger and the other dry ingredients were added.

The extra water in the mix, which allowed for easier blending, was removed by heaping the clay on a plastic tarpaulin and allowing the clear water to run off over a few days. The resultant body was sticky. I found the easiest way to work with it was to roll it into slabs between sheets of heavy-duty plastic.

Photographic Imprints

Initial trials of imprinting the porcelain body with ceramic stamps were effective. The clay held the imprint crisply and I was encouraged to think that a photographic image would be possible if the right type of ‘stamp’ (plate) could be found. I had used solar etching plates to produce photographic etchings in printmaking and thought it might be possible to use such a plate to imprint the clay. Unfortunately, the solar plate was unsuitable for this process because the light sensitive emulsion on the plate was unable to maintain the sustained contact with the clay body necessary to imprint it. The emulsion absorbed moisture from the clay body, expanded and separated from the backing plate. The resilience of the high cellulose content in the body also prevented it from being able to hold the fine imprint to any degree that would produce an effective image.

In a photographic exhibition of work by Jenny Pollack and Louis Vidal, entitled ‘Passages’, (Customs House Sydney, November 2000) I saw embossed photocopies of photographs that had been produced to make a tactile, readable surface for people with impaired vision. These photocopies are produced with a special heat-sensitive paper which when passed through a PIAF machine reacts to raise the areas printed with ink to give a kind of Braille photocopy. With the help of Michael Keighery at the University of Western Sydney, Milperra, I was able to produce a photographic 3D image. By using a printing press, I imprinted this image into a standard clay body and the imprint was sharp and readable. When I repeated the process with the porcelain paperclay the resilience of the cellulose once again reduced the clarity of the image. I discovered that by allowing the paperclay mix to age (at least one month), this resilience was reduced and the readability of the image improved, but the results read more as a silhouette than a photographic image.

An article in Ceramic Review May/June 2001 presented research by Helen Smith at the University of the West of England on the potential of using flexography to emboss paperclay with a photographic image.

Further inquires within the printing industry led me to a du Pont product named Cyrel®. This proved to be just what I was searching for. Cyrel® is a flexible vinyl plate of approximately 10 mm thickness to which a photographic image can be transferred by placing a photographic transparency on the plate and exposing it to intense UV light. The process duplicates even the minutest detail and the resulting stamp-like plate will effectively imprint the porcelain paperclay.

I roll the clay to a similar thickness to the Cyrel plate, spray the top of the slab with a fine mist of water and smooth the surface with a plastic ruler. I then leave it to a dry leatherhard state and use a rolling pin to imprint the clay with the plate. By drying the imprinted slab slowly over a few days I avoid any warping. The slab is then fired slowly on a flat even bed of white silica sand in an electric kiln to cone 8.

The fired porcelain paperclay is porous and fragile. As Steve Harrison suggests, it can be painted with acrylic medium to give it strength and flexibility and the medium gives the surface an almost imperceptible luster. Early results have been most encouraging, to my mind opening up enormous possibilities for future development.

3D Forms

In my initial attempts to produce three-dimensional forms, I experimented with various construction and firing techniques and although the paperclay was effective at the construction stage, immense care had to be taken during drying to avoid warping. I found the most effective construction technique was to work with leather hard or even totally dry slabs that had been cut to the desired shape with a sharp blade and to join them with a slightly drier than normal paper porcelain slip. It was also possible to roll partially dried slabs into cylindrical forms. However, during firing, even with meticulously built supports, the forms warped slightly and although in some cases this was acceptable, it was too ‘organic’ for the type of form I wished to produce at this point.

For my purposes, I overcame this weakness by constructing the forms after firing. In the first instance where I wanted to convey a sense of precariousness and tension, and the fragility of sanctuary, I layered the sheets to create the 3D form. In another piece that addresses the effort that must go into the construction of sanctuary, I perforated the edges of the sheets and sewed them together. The results have been rewarding, to my mind embodying all the fragility and vulnerability I had hoped to convey.

Porcelain paperclay while challenging traditional methods of production, has presented possibilities for my studio practice. The edges possible with this body, its translucency and affinity for light, and its seeming fragility are qualities I intend to investigate further.

Because of the health hazards associated with ceramic fibre and dry paper pulp, it is essential to use a facemask and gloves while mixing this body. Mix the clay in an area with sufficient ventilation and when touching the ceramic fibre, cover as much of your body as possible with protective clothing.

At the time of writing, Gaye Stevens was a M Des(Hons) candidate at the College of Fine Arts, University of New South Wales, Australia. Supervisor: Jacqueline Clayton.