DATA ON VISCOSITY OF INDIANA CLAY SLIP WITH ELECTROLYTES IN REGARD TO THE CASTING OF TERRA COTTA1

A presentation of data on the use of several electrolytes with one particular clay, to wit: Indiana clay, such as is used by the terra cotta manufacturers of the Chicago district. The various electrolytes used were sodium carbonate, sodium silicate, the two combined half and half, gallic acid, and tannic acid. Data was obtained by determining relative viscosities with the use of a flow viscosimeter, and by measuring the thickness of wall cast in a given time. Sodium carbonate, used alone, seemed to be the most satisfactory. Tannic acid shows possibilities, but so much is required as to be commercially impractical.