The quality advantages of the Speedball Diazo system over the Speedball bichromate photo emulsion and sensitizer are: The entire container of photo emulsion may be sensitized. The sensitized system has a "pot life" of two months at room temperature and 10 months when refrigerated. The bichromate system has a 12 hour shelf life. The diazo system coated screen can be stored for two weeks at room temperature in a dark area before exposure. The old system only allowed 8 hour storage. The diazo system yields a longer lasting stencil with sharper edges. The diazo photo emulsion kit includes 8 oz photo emulsion, 8 oz photo emulsion remover, 1 oz diazo sensitizer and instruction sheet.