a matrix for plastic letterpress printing plates and the method of formation thereof are presented wherein the matrix material prior to molding is thicker than the desired molded matrix . the &# 34 ; non - printing &# 34 ; areas of the matrix are compressed to at least seventy percent of the density of the compressed &# 34 ; printing areas &# 34 ; in forming the matrix , and the matrix may then be ground to desired thickness to obtain desired heat transfer characteristics .