|Monthly Tech-Tip |
The branch of the ceramic industry that manufactures porcelain toilets and sinks and other utilitarian heavy items used in bath and shower.
Key phrases linking here: whiteware - Learn more
A term used in the ceramic industry to refer to the branch that manufactures toilets and sinks and other utilitarian heavy items used in bath and shower. These have traditionally been glazed glossy white (thus the name whiteware) although they can be any color. Traditionally ware is made from porcelain (composed of ball clay, kaolin, feldspar, silica), fabricated using a slurry casting process, green-glazed using heavily opacified glossy glazes and fired undecorated to high temperatures (e.g. 2300F) to vitrify it. Bodies typically fire off-white or ivory however many companies cut costs using iron stained local materials since these can be hidden behind the opaque glazes.
Of course this type of body and glaze can be used to create utilitarian functional ware but that sector is more commonly referred to as “table ware”.
The white ware industry is world wide and very large and a heavy user of materials and energy. Companies often couple their whiteware production with wall and floor tile and try to follow fickle design trends. The industry is old and established and techniques and materials tend to be conservative. R&D is less common than other ceramic sectors, companies often copy trends and techniques being done in other places.
The sheer size, weight and perfect surfaces of pieces are a marvel of engineering. Mold makers in the industry must have exceptional design and technical knowhow. Technicians struggle to accelerate the difficult casting process to get higher production. Drying the complex heavy shapes efficiently yet without cracking is also a big challenge. Even more difficult is firing the heavy ware evenly enough to avoid cracking (shrinkage occurring during firing can be very high) and cooling the kiln slowly enough to avoid dunting (since the body is heavy in quartz) . Glaze crawling is common because of the high zircon opacifier content. Glaze surfaces must be highly durable and easy to clean. There is also a constant search for a less expensive way to opacify than with zircon.
|By Tony Hansen|
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