- The plotter machine prints the plan from the computer to a translucent film paper.
Ammonia blue printing machine
- The ammonia blue printing machine is then fed with the plotted plan in translucent paper and ammonium paper and rolled through a lighting beam
- The lighting discolours the yellow sulphur surface leaving shades of prints on the ammonium paper.
- The ammonium paper is then placed in ammonium vapour which impresses the shades into clear blue prints.