The use of a ball clay is therefore limited in white wares because it will spoil the color.
ball clay is very plastic, easily vitrified, but is not white.
For the same reason, great care is needed in any endeavour to sell a ball clay from an hitherto unworked deposit.
Pipe clays are an inferior quality of ball clay; they contain rather more iron and alkalies and considerably more silica.
The ball clay from Poole is dug in the neighbourhood of Wareham, by Mr. Pike.
For earthenware or china, the English potters use only two sorts of clays: the ball clay, also called blue clay, and the kaolin.