Process for developing electrostatic

Claim 1

IN A METHOD OF ELECTROSTATIC PRINTING WHICH COMPRISES: PREPARING A LIQUID DEVELOPER COMPOSITION CONSISTING ESSENTIALLY OF FINELY DIVIDED ELECTROSTATICALLY ATTRACTABLE SOLID OPAQUE PIGMENT MATERIAL HAVING A PARTICLE SIZE NOT GREATER THAN 40 MICRONS AND WHICH IS DISPERSED IN A HIGH RESISTIVITY ORGANIC LIQUID HAVING A SPECIFIC RESISTIVITY OF AT LEAST ABOUT 109 OHM CENTIMETERS, AND BRINGING SAID LIQUID DEVELOPER COMPOSITION INTO CONTACT WITH A MEMBER BEARING AN ELECTROSTATIC CHARGE IMAGE WHEREBY SAID CHARGE IMAGE IS CONVERTED TO A VISIBLE IMAGE BY SELECTIVE DEPOSITION THEREON OF THE SOLID CHARGED PARTICLES IN SAID DISPERSION, THE IMPROVEMENT WHICH COMPRISES MODIFYING SAID LIQUID DEVELOPER COMPOSITION BY INCLUDING THEREIN AN ORGANIC MATERIAL WHICH IS SOLUBLE IN SAID LIQUID AT ELEVATED TEMPERATURES AND WHICH IS RELATIVELY INSOLUBLE IN SAID LIQUID AT TEMPERATURES OF ABOUT 20*C, AND WHICH IS ELECTROSTATICALLY ATTRACTABLE WHEN IN SOLID FORM AND WHICH COMPRISES A SOLID PARTICULATE MATERIAL OF THE GROUP OF MATERIALS CONSISTING OF POLYAMIDES AND SHELLAC.