| Celina on ceramics:"Kneading the Clay, Part I" |
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Before intending to shape a piece of clay there is the need of remembering some very important aspects: inside the walls of a pot, no air pockets should be allowed.
Let us see what happens with an air pocket inside the pot walls. After drying, the clay shrinks, this means that some pressure is already exerted on the pocket. When warming up the pot, the water inside the clay boils and vapor is emitted. Only this pressure may be enough to cause the pocket explosion and consequently to break the pot, but if not, later, in the measure that the temperature rises and the clay passes through different transformations before becoming vitrified, the explosion may break not only the pot itself but the pots around if not the costly kiln furniture. So kneading to expulse any air pockets is a very important task. On the other hand, any clay let to stand even for a short while, dries in the skin. If the pot is made without care for this, dry parts may go to only-God-knows where and these, shrinking less that the humid parts will deform the piece. Moreover, any clay imperfectly processed may have been ground to different sized molecules, and those bigger ones need to be evenly distributed. This way, kneading has also other objectives and one no less important is to homogenize the clay. Most potters separate these two processes: to homogenize hardness & particles size and to expulse any air left inside. These, in Japan, are called, the former "ara-neri" or “rough kneading” and the second, "kiku momi" or “Chrysanthemum kneading” which usually is translated as “spiral kneading” Again, when looking different cultures, it is amazing to see the diversity of ways that potters have invented to homogenize and to expulse any tiny remains of air inside the clay. But kneading is a very hard work especially when big pieces are intended; developed wisdom to cope with this task reveals in some ways the background culture of each region. Rough kneading, in China, was firstly done with the feet. The clay was placed on the ground and the potter had to push the clay rhythmically in a circular motion with one foot while the other had the task of supporting him. Still, among others, quite a few Korean potters, foremost inheritors of Chinese techniques, use this method. Celina would be pleased to try to answer any comments & questions
related with her blog text, and when not able to do so, she gladly would go in quest for an answer among clay-people around Remember if you want to buy Celina's book about the Japanese techniques of crefting the ceramics please send an e-mail at info@forumartistico.com or visit www.e-bay.com.
Copyright©Celina Clavijo Kashu2010 for Forum Artistico Celina's Past Blogs: Celina on ceramics:"Iron content in clays" Celina On Ceramics
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