- Material sciences and production techniques -


Clay reinforced with paper fibre is an excellent material for large pieces, sculptures and slabs because of its remarkable green strength and light fired weight. In paperclay, the clay particles glue the paper fibres into a network and thus form a supporting structure for an unfired object and prevent cracking. The paper fibres burn away from the clay in firing, leaving the object porous. 

The aim of this research has been to improve the handling properties of large objects at the green stage. It was financed by the Ministry of Education in 1993 and the Academy of Finland in 1993 - 1994. Results of the research have been published in the proceedings of the 8th Cimtec conference, Florence Italy, 1994 and will be presented as a licenciate thesis by Leena Juvonen in 1996. 

Essential tests in the research have been bending resistance, water absorption, linear shrinkage and efflorescence. Material tests have been carried out on different kinds of fibres like cellulose, waste paper and sludges from a paper mill in co-operation with the University of Technology. 

Along with material tests there has been an artistic project testing paperclay in practise. Large, thin bowls and slabs have been made by pressing on plaster moulds and painting with ceramic pigments. This project is part of Varde the Nordic design programme, which was exhibited in London, Rome, Budapest, Berlin and Vienna during 1994 - 1995. 

The use of paperclay is economical. Instead of requiring new paper, all kinds of waste paper, recycled paper and pulp are good material to be mixed with clay. Material and energy costs are cut down as paper fibre added to the clay body fills up the clay mass. Paperclay also withstands rapid temperature changes, which shortens the firing time and saves energy. 

Working with paperclay is more spontaneous than with conventional clay bodies. Paperclay withstands quick drying and firing without cracking or warping. Large, thin paperclay objects can be raw glazed and firing can be started even when the object is still wet. Paperclay questions the traditional restrictions prevailing in ceramics and gives more creative freedom. 

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Leena Juvonen
Research Scientist

University of Art and Design Helsinki UIAH
Department of Ceramics and Glass
Hämeentie 135 C 
FIN-00560 Helsinki, Finland  
fax: +358 9 75630275