Gum Question On Wash/Frank Rotary Press Coils

Quote:
...The Rotary Press issues were also gummed in a different manner. The old (i.e., flat plate) methods required each sheet to be gummed individually. The rotary press stamps were printed on continuous rolls of paper and fed continuously through a perforator. To cut the rolls into separate panes for gumming would further delay production. Therefore, it became necessary to apply the gum by some continuous means. It was applied through a roller. At first it was flat but later grooves were added to insure that the gum would be spread evenly. These grooves are also known as "gum skips". Rotary press coils in mint condition must show this natural groove in the gum as illustrated above. It will vary at times but will still be present. Vertical coils will show this gum skip about 50% of the time since the grooves were spaced wider than the width of a vertical coil...

Quote:
Rotary press coils in mint condition must show this natural groove in the gum as illustrated above.