|Monthly Tech-Tip |
These cone 6 clear-glazed porcelains demonstrate just how white you can make a porcelain if you use white burning kaolins and bentonites instead of ball clays. Both contain about 40% clay. The one on the left employs New Zealand kaolin and Veegum plasticizer, the one on the right Kentucky ball clays (among the whitest of ball clays in North America) and standard bentonite. Both are zero porosity. The glaze surface is a little more flawless on the right one (possibly because ball clays have a lower LOI than kaolins).
The purest of all clays in nature. Kaolins are used in porcelains and stonewares to impart whiteness, in glazes to supply Al2O3 and to suspend slurries.
A fine particled highly plastic secondary clay used mainly to impart plasticity to clay and porcelain bodies and to suspend glaze, slips and engobe slurries.
How do you make porcelain? There is a surprisingly simple logic to formulating them and to adjusting their working, drying, glazing and firing properties for different purposes.