Mr. Bob Gumbinner's Plate History now covers the C machine which made grained anodized plate. This "pumice grained" and anodized base became the backbone of Polychrome plates till Columbus plants started to produce electrolytically grained plates much later on. Our licensee Fuji Photo Film's plant took the concept for their plants later on.
After
a year or so it was decided to order a third machine--the C machine.
This machine started with a two axle unwind stand from Deprieux and a
tape heat seal unit. (Later an accumulator was added. Most of the
unit was built by Century Engineering. This included a six double
brush grainer with a slurry spray for the top side of the aluminum
foil and immersion pans for graining the bottom side when desired.
After going through a rinse section the aluminum foil went around a
contact roller connected to the cathode side of two AC/DC anodizer
units either by a commutator or brushes. Aluminum anodes were
suspended above and below the foil. The first set of anodes were at a
low voltage to prevent burning. The second set at a higher voltage. After
rinsing an interlayer of either silicate or potassium zirconium
hexafluoride was applied, this was followed by a hot and cold rinse.
After drying the aluminium foil was coated in one or both sides
before being cut into the proper plate size.