A little background information about the origin and an explanation of what paper clay is
Rosette Gault of Seattle, WA (publisher of the booklet Paperclay for Ceramic Sculptors) has been promoting paperclay in many publications in recent years. Brian Gartside, a studio potter from New Zealand is also an early promoter. Paperclay is available from a number of clay manufacturers in North America. Rosette prepared this statement for us:
"Find out more about the many varieties of paper clay earthenwares, terracottas, raku stonewares and porcelains for firing in kilns at www.paperclayart.com. See what the expanded sculptural possiblilities of this clay for firing in kilns can be. These types of clays can be used for vessels, pots, tiles, sculptures, figures, casting and/or pressmolds, wall works, murals and are normally compatible with all kinds of glazes, terra sigillatas and in all types of firing. To try paper clay, you can mix your own or in certain areas even get some ready pugged in bags. Details can be found at the site as well as bibiliography, workshop listings, book and supply sources worldwide."
Here is some of the information we are collected about paper clay:
Combining clay and cellulose fiber from paper produces a versatile clay body that can be molded, modelled, slabbed and coiled in ways that seem to break all the rules of working with clay, and by people possessing little skill. The unique properties of paper clay are thought to be due in part to the fact that the fibres are hollow and the tiny clay particles are able to fill them from the inside. Paper clay is claimed to be impossible to crack, difficult to warp during drying and capable of being rewetted from bone dry by immersion in water. It is also claimed that it can be joined at any stage, dry to wet, wet to leatherhard using the paperclay slip as a glue and is said to develop very high green strength that makes it possible to create much lighter ware. However, we found it difficult to use on the wheel and almost impossible to trim or carve (others claim they are able to do so).
One user adds a paper pulp slurry to a clay slurry in a proportion of 30 volumetric parts paper slurry to 70 parts clay slurry (a long ruler is held in the slip to get the right level). Another person uses 3-5 gallons of wet paper pulp to 100 lbs of dry body mix. A sample of good material we tested showed only 10% loss of weight on firing. Taking into account LOI it would appear that about 2-4% of the mix is paper by dry weight. When a dry slab is broken, there should be a fine even network of paper fibers. Thus the amount of cellulose possible is far higher than with other fiber or particulate fillers.
Paper can be broken down by tearing it into shreds and soaking in hot water. Pure cotton and linen papers are best because they lack lignin which can contribute water resistance. Paper products and cardboard that contain glue or kaolin do not break down well in water. Papers that tear easily tend to make short easily liberated fibers work best. Some people add some soda ash to the wet paper-water mix, although we are not sure why. Pulp mills can sometimes provide 'paper linters', large thick sheets of paper fibers that break down easily in water.
Paper clay will quickly begin to smell so it should be stored in a freezer or used soon after making. Adding antibacterial agents to the paper slurry may also be helpful (i.e. chlorine bleach).
Since the organic fiber must burn away during firing, slow firing and adequate draft are needed from the 300-500C range since significant smoke is generated. After firing the surface has the same appearance as normal clay.
Here is an interesting comment from Graham Hay:
"You provide a good overview on paperclay however it only really covers the USA experience and products. A more international focus source of information, complete with complete journal articles (copyright approved by author and publication) is at www.grahamhay.com.au/paperclay.html. There is an up-to-date automatic search of clayart discussions by potters on paperclay, list of paperclay suppliers around the world etc. I do not have commercial links to maunufactors or sellers of paperclay (unlike most paperclay specialist websites). For the last ten years my principal activity is using paperclay and collecting and distributing paperclay information via workshops and classes."