Presensitized
Printing plate 4
After
we started to manufacture the presensitized plates we hired a number
of chemists to do quality control and then to find another material
besides silicate which could be used as the interlayer between the
aluminum and the diazo coating. I worked with one chemist on organic
coatings and with Ibert Mellan, who had published several books on
chemicals, on inorganic coatings. He and I discovered that dipping
the cleaned aluminum plate in a 2% solution of potassium zirconium
hexaflouride at 160°F. made a good presensitized offset plate when
coated with the diazo. We applied for a patent for this process on
Dec. 29, 1958. We were granted patent #2,946,683 on July 26, 1960.
We also received patents on this process in Japan and Europe. After
the patent was issued in Japan, Fuji Photo Film, the main
manufacturer of photographic film in Japan through the Mitsui
organization licensed this patent for a one and two thirds per cent
royalty and technical interchange. Over the years, Polychrome
received over seventy million dollars ($70,000,000) in royalties
While most of the improvements came from Polychrome, we did get from
Fuji a formula for a positive presensitized plate coating which was
an ester of diazo oxide with an acetone-pyrogallol polymer.