metal to which the coating is applied the chemical constituents used as mill additives in both cases above are obtained commercially and a typical mill additive may have the following composition ______________________________________host glass table i table ii 1000 gr lithium silicate 100 gr bentonite clay 25 gr syloid electrolyte 5 gr water 500 cc______________________________________ the chemical additives are ground or milled and then screened through the proper mesh sieve before they are added to the frit to make the powder or slip too coarse a particle size will have several adverse affects on the character of the coating first the particles will not be distributed evenly thereby giving dense pockets of additive substances that will have drastically different physical and chemical properties than the areas of lesser concentrations this type of situation will lead to the development of undesirable strains and stresses between the phase boundaries the continuous melting of the coating material will be interrupted by concentrated pockets of chemical additives thus giving an uneven and rough texture to the coating surface by grinding the dry ingredients of each batch of mill additives in a ball mill the individual particles of the ingredients will be thoroughly distributed throughout the mass whereby the additives are properly dispersed throughout the host glass matrix whereby the continuity and quality of the coating can easily be controlled too fine a particle size will lead to undesirable separation in the powder application the finer ground additive materials will separate from the.