1. IN A PROCESS FOR PRODUCING A PRINTING PLATE FOR USE IN A COLLOTYPE PROCESS, THE STEPS OF COATING A PLATE WITH A LAYER OF A BICHROMATED LIGHT-SENSITIVE GELATIN EMULSION, SAID EMULSION HAVING A PH BETWEEN ABOUT 3 TO 6 AND CONTAINING EVENLY DISTRIBUTED THEREIN A WATER SOLUBLE ALDEHYDE SELECTED FROM THE GROUP CONSISTING OF DIALDEHYDES AND KETOALDEHYDES IN AN AMOUNT OF ABOUT 0.045 TO 0.15 MILLIMOLE PER GRAM OF GELATIN, THEN EXPOSING SAID EMULSION TO THE ACTION OF LIGHT PASSING THROUGH A NEGATIVE, WASHING THE PLATE TO REMOVE SUBSTANTIALLY THE BICHROMATE, AND TREATING THE SURFACE OF THE EXPOSED EMULSION WITH FORMALDEHYDE IN AN AMOUNT AND FOR A TIME JUST SUFFICIENT TO REMOVE THE TACKINESS OF SAID SURFACE.