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Earthenware/ceramics are fired at temperatures around 1050 degrees centigrade.
Porcelain on the other hand is fired at temperatures up to 1400 degrees centigrade.
In this difference lies the secret of porcelain; at these extremely high temperatures
the minerals in the porcelain melt together and form an impermeable, and very
strong bond. That is why porcelain can be moulded into very thin, translucent
shapes. This is due to the composition of ceramics ever impossible. When firing ceramics this melting together of minerals does not occur so the ceramics has to be more massive than porcelain in order to obtain the same strength. Ceramics also need to be glazed in order to make it impermeable to water. Since the goal with the creation of Delft Blue pottery has been to recreate the Chinese pottery as good as possible, it has always been susceptible to changes made to the technique. One of the most important changes was when people started to use English clay instead of local one. This clay has a natural white color without the need for a special tinglace. This made it possible to paint right onto the earthenware, and to be glazed with a clear, transparent glace. This technique is still used today, but every new technique that leads to improving the quality is used. Delft Earthenware is actually a mixture of many techniques that has become famous through the ages. Despite the many changes, the skills haven't lessend. On the contrary, the demands placed on a painter have increased during the years. The Chinese used a lot of blue with the creation of the pottery. The main ingredient for this color is Cobalt-oxide, a natural compound well suited to withstand the extreme temperatures occurring when it's being baked. Only later they introduced different colors like red and green, and then Delft Polychrome, a technique where many colors are used. (poly = many, chromo = color). They tried black for a while, but it was never a hit. |
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