Control Procedures for Lithographic Chemicals Manufacture.

The control of lithographic chemicals is a subject with which the average lithographer has only a limited knowledge and perhaps only a minor interest. However, the quality of work turned out in a litho shop is directly affected by the uniformity of the chemicals used by the photographer, the platemaker, and the press room operator. The control of lithographic chemicals may be broken down into three major classifications; control of raw materials, control of the manufacturing process, and control of the finished product. If control of any of the three classifications is neglected, the uniformity of the working properties of the finished produce will invariably suffer. The methods of control applied to the three major classifications can best be set up by the establishment of specifications. Specifications on raw materials and finished products should designate the maximum and minimum tolerances of properties, such as viscosity and percent solids that have been found to affect directly the working characteristics of the finished product. Specifications on manufacturing processes should designate the maximum and minimum tolerances of process variables, such as temperature and acidity, the control of which has been found to be vital to the manufacture of a uniform high quality product.