Here is a little to help with the differences between the flat plate and the rotary press printing methods.
There are four basic steps in the flat plate process:
4. Pressure impression
Using the red position numbers:
As the plate pallet rotates from 4 to 1 it passes under the inking station where the plate is covered with ink
As the plate pallet rotates from 1 to 2 it passes through the wiping mechanism where the excess ink is removed
At 2 the printer uses the polishing block to force the ink into the recesses in the plate. He also uses the whiting to remove any ink from the top of the plate.
At 3 the paper sheet is placed on the plate.
As the plate pallet rotates from 3 to 4 it passes through the impression roller which presses the moist paper into the plate recesses and producing the printed impression.
At 4 the printed sheet is removed.
Below is a R. Hoe & Co. flat plate press from BEP. This one is printing currency but is the same presses that printed stamps. This press was a for plate press with the plate pallet rotated by chain drive from station to station. You will notice that the plates are completely flat.
There are three basic steps in the flat plate process:
3. Pressure impression
With the rotary press a continuous roll of paper (web) was used. The paper was fed between the rotating plate drum and the impression roller where the print impression was made. Each revolution of the plate drum would print 2 sheets, one of each plate. As the plate drum rotated it was continuously inked and wiped. The paper would continue around the top of the press and was rolled up ready for gumming, perforating and cutting. With later machines the gumming and perforating were done on the press so all that was left was the cutting into panes.
Above is the 2 plate drum consisting og 2 semi-circular plates.
Above is a larg Stickney rotary press.