Prékopa Ágnes (szerk.): Ars Decorativa 30. (Budapest, 2016)
Kornélia HAJTÓ: Zsolnay Pyrogranite: Tradition and Fact
maximum temperature produces ceramics of the greatest possible density and highest possible strength. In the past, this temperature was determined by firing test bodies. To reduce shrinking, powdered fired ceramic (chamotte) was added to the raw clay. The material and grain size of the chamotte additives show wide variations in the samples tested. The cross section of one sample shows that clay mixed with finely- ground chamotte was first pressed into the plaster mould, probably to attain a smooth surface, followed by a layer of clay with coarser-grained chamotte to give the piece greater strength (Fig. 5). Two ceramic items made of the same material and by the same technique but placed in different parts of the kiln could end up with different properties because of variations in firing conditions. Another important factor in firing was the fuel used in the kiln. Zsolnay wrote of this to his son Miklós from Karlsbad: “The benefits of high-quality kaolin and coal available to the ceramics industry here are inestimable. I am sure that if the Czech factory owners woke up one morning to find their coal to be of the same quality as ours, they would lose their heads and their money. It is unbelievable how easy it is to fire with the shale-free coal here. You will believe, my son, that the quality of fuel has an enormous role in our industry, and that most of our difficulties arise from the poor quality of the coal that is available to us. ”40 134 5. Architectural ceramic fragment from the Museum of Applied Arts building. Presumed original. The use of two kinds of ground chamotte-tempered clay is clearly apparent. Photo by Kornélia Hajtó
