Updating view. Please wait...
The fine stoneware compares with porcelain in its technical characteristics. Like porcelain it is formed with the help of moulds, jolleyed and cast. In addition awkwardly shaped articles are formed under pressure.
Articles of fine clay stoneware are particularly attractive. The brownish hue and the slightly grainy textured structure of the surface are often left unglazed as part of the decoration.
As in porcelain production reliefs are engraved into the plaster model. With hand-finished products, the reliefs are shaped manually. After first firing the pre-dried fine stoneware at approximately 900 degrees C, the body is either colour glazed - whereby the glazing provides the colour - or it is painted by hand and followed by a coat of transparent glaze.
Another method of decoration on Rosenthal ceramics is the painting on the un-fired glaze.
During the second firing process at approximately 1200 degrees C the fine stoneware becomes very dense, making the body watertight. Despite the high firing temperatures, the colour range of under-glaze decorations is almost unlimited. Porcelain on the other hand is fired at a temperature of 1400 degrees C and this limits the colours for under-glaze painting on this material considerably.
In addition decoration such as a transfer or hand painting can be applied to dark or opaque colour glazes. During a third firing the decoration is melted again into the ceramic glaze at a temperature of 1200 degrees C. At this temperature the glaze is softened again, causing the colours to sink into the glaze, which forms a protective coating. When the glaze is intended to be the colour base it is usually dyed with metal oxides. Depending on the concentration of the oxides and the consistency of the glazes, colours differ in intensity. The metal oxides change during glaze firing according to the prevailing kiln conditions.
After each oxidizing firing, that is in an oxygen enriched firing atmosphere, the metals contained in clay and glaze retain the colour of their oxides (e.g. Copper - green).
When fired with reduced oxygen, the metal oxides change back into their metal colours (e.g. copper - red shades).
The potter is particularly attracted by the use of versatile coloured glazes. Because of their composition they react to the slightest variation in temperature during firing with sensitive colour changes. Depending on where they are placed in the kiln, colours vary from one piece to another. This gives each its unique character. The potter increases these typical characteristics even more by dipping the article whole or partly into different colour glazes or glazes of different concentration.
Fine stoneware is ovenproof and if the decoration is under- or inglazed, also dishwasher safe. This applies to everyday ware as well as to gift articles. Fine stoneware is also suitable for the microwave oven with the exception of decorations containing precious metals (gold, platinum) and iron oxide crystal glazes.
However, sudden changes in temperature should be avoided.
Because of its relatively strong, hard-fired body, fine stoneware is highly durable even when subjected to the wear and tear of daily use and automatic dishwashing.
Fine stoneware is thicker than the thin walled porcelain because of the materials used which means that it is better able to retain heat. Therefore plates, cups and serving dishes keep their contents hot for longer. The crockery can also be warmed without becoming too hot to handle.
In English speaking countries tea is therefore often prepared using ceramic teapots and drunk from ceramic cups. It is said, that the good heat insulating properties of ceramic crockery prevent a quick cooling of the drink and allows it to develop itsfull aroma.