228
Fig. 2. 29. central airroom; 30. axis of the plungers; 31. one of the
conduit pipes; 32. central conduit pipe for air of 2\ atm. pressure.
1
of
for
atm.
conduit
pressure
central
2
air
The sheet is completely flattened between the two plates. By
hand one pushes the four knobs, so providing the sheet with four
punch holes. When the cock is opened again, the upper plate is
lifted up and the punched sheet can be taken out.
The general negative on "cronaflex" is a reverse image. Colour
separation guides are right-reading and are punched in the face-up
position. The general negative (reduction of the base map) is punched
face-down.
For making a combination of two or more scribed sheets the pre
punched sheets which have to be exposed can be fitted together in
exact register by means of a solid glass plate with studs located on
it in the same position as the punch holes in the sheets.
Therefore we place the (thick) glass plate in a vacuum frame.
Now it is possible to put the sheets to be contact printed, with the
punch holes on the studs in the glass plate. To ensure that the two
sheets will remain on the studs, a little rubber ring is put over them.
26
14_
Fig. 3. 23,24. two sheets to be contact printed; 25. stud in the
thick glassplate26. rubber ring.
