New Century Arts Inc.

Because there are variables beyond my control (clays, papers, water, mixing errors and etc) always pre test fire what you have before a big project. No guarantee can be offered that 'alternative" commercial paperclays now on the market will meet the all the performance advantages of my high performance trademark P'Clay® brand only available from licensed manufacturers/distributors.


Ventilation of Kiln During Fire

An example of one of many designs for a ventilated portable indoor electric kiln. Exhaust sulphur, wax, glaze residue, and organic matter burnoff fumes are sucked outside the room via the hood. Indoor kilns, like machine clothes dryers, must have vents leading exhaust outdoors. These do a great job.

A strong exhaust fan in a window nearby kiln is also a good idea.

Venting of gas kilns is typically up a chimney.

Loading greenware in a reduction natural gas high fire kiln for a one fire (skip the bisque fire) is stress free and saves the expense and time of two firings. Why?

1. Double the green strength. Risk of fracture is half what it is in a traditional clay. Joins can be testedand re done if needed.

2. If the form gets bumped it could be repaired.

3. Glaze was applied to the greenware.

See examples dipping one fire greenware bowls in the pottery section>>>>>

firing in kilns

Fire paperclay as normal to any temperature the base clay is compatible with.

P'Clay can easily take oxidation or reduction, electric, natural gas, oil, or wood, burnish and terra siggilatas, pit, saggar, raku, majolica. It can take crystal glazing, lustre, and china paint. It can It can take fast or slow fire schedules. It is compatible with glazes compatible with the base clay.

When properly balanced paperclays fired to maturity they are hard, water tight, and micro voids eventually fill in and seal up as kiln temperature increases. Test fire a sample to be sure. Many earthenwares can be fired way hotter than rated- up to cone 5- as paperclay if your kiln is accurate.

The paper leaves the clay early in fire..... way early 451F. If base clay is bad batch to start no amount of paper will hide the fact or rescue. The clay ingredients in the recipe need to be balanced too. Use vented kilns.

One Fire: One fire paperclay is a practical option because the greenware is durable enough to handle the ware, to dip briefly into wet glaze, and not deform. The greenware surface absorb enough water in the glaze to allow a decent layer of glaze to deposit on the surface. Traditional clay requires bisque immature state fire to do this.

Biscuit State intermediate Fire: With traditional clay, an intermediate bisque fire was needed to set the ware so it could be handled with less risk and to make it absorbent of water for easier glazing. Paperclays dont require bisque but if they are bisque fired then, bisque at least to cone to 04 or even 03- not so called cone 08 temprature some use. The paper fiber will be gone. Bisque ware of of stoneware and porcelain paperclays that are low bisque underfired can be fragile.

Porcelain: Most porcelains, paperclay or not, need real care not to overfire. They need just as much care in firing, and placement in the kiln as non paperclay porcelains. When in doubt lower the finish temperature a cone or two and/or dont soak the kiln at maximum heat either. Beware hot spots that the computer sensors do not account for or show you. Reduction fire will also affect the maturing process... usually. Packing and loading of the kilns is very important also. Some report that porcelain body reduced celedons shift in color slightly.

Firing in Electric and other Kilns: About Fumes and Timing

The sulphuric and other burnout fumes from any clay firing should be ventilated, paper or not. Paper fiber exits the clay body (451F/253C), early on in the fire, similar to like wax burnoff that is before cone 032 will melt. The process finishes in the first several hours of an 8 hour fire going to bisque 1000C or higher. The combustion smoke and moisture exiting does not hurt the electric wire kiln elements in a dark slow heating kiln (451F/253C). Indeed the amount of paper in paperclay adds up to less than the handfuls of raw crumpled paper sometimes used to support handbuilt structures.

It is unwise to put dry paper or other combustibles directly into a red hot (around 1000C 1850F and up) electric kiln. Superheated gas ignites the paper instantly. Too much fuel all of a sudden, and not enough oxegen so creates a red hot smoke. Ultra hot smoke (from incomplete combustion reducing atmosphere) will corrode electric wireheating elements over time and shorten thier life. Also radical temperature changes will stress heating elements- which is why most do not raku with electric kilns. Presence of paper or other combustibles in an electric kiln at glowing red heat is not recommended.

By the time the kiln temperature reaches (1000C 1850F or so) internal paper pulp fiber has been absent for hours, having exited the clay at F451/C253 degrees and can't, therefore, cause reduction, nor a superheated gas just explained.

My book, and others, have full firing schedules to guide you in learning curve.

Take some clay classes and really get practice with firings before investing in kilns.

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