Printing Tests with Various Plastic Printing Forms.

In this paper it is reported about printing tests with duplicate plates of 8 different materials: 1 stereotype, 1 electro, 2 bakelites, 3 polyvinyl chlorides and 1 polyvinyl acetate. The physical and chemical properties of the metallic plates are compared with those of the plastics. The new plastic duplicates show some remarkable advantages compared with the well known stereotypes and are in most cases equal to good electros. When stored for a long time the plastic materials may deform to a certain extent and by repeated washings with aromatic or chlorinated hydrocarbons the plastic duplicates may be destroyed (thermoplastic type). Several plastics show printing properties which are as good as those of an electro and distinctly superior to a stereotype. The ink transfer too from soft thermoplastic plates, like polyvinyl acetate, to rough paper is excellent. It is to be supposed that some yet existing difficulties in treating and manufacturing plastic plates may be overcome soon. Runnability tests on a cylinder letterpress up to 100,000 impressions demonstrated that the high resistance to wear of most plastics is remarkably superior to that of stereotype. Bakelites and polyvinyl chloride may be considered as resistant as the copper shell of the electros.