Parts of thirty-two sheets from th? 1 10 000 map series (sheet size 60 x 70 cm)
were photographically reduced to the scale 1 80 000 on dimensionally stable
material. The resulting diapositives were assembled. A sheet of Astralon (translucent
plastic), provided with a grid at the required scale, was subsequently placed over the
assembled diapositives, with the drawing-surface face-up. The map detail could then be
drafted with a special etching ink (two parts of Hausleiter Tusche WU, one of
Hausleiter Abdecktusche). This procedure provided a mirror reversed drawing which
could be used directly as original copy for the pressplate making and therefore saved a
reversal copy during further processing.
GENERALIZATION
The detail of the reduced 1 10 000 map sheets could not be redrawn without
far-reachmg cartographic processing. That included exaggeration and generalization of
detail in a manner which could satisfy the purpose of the map. The generalization has
been based completely on the prolonged experience of the cartographer, on a clear
understanding of the map purpose and especially on a thorough knowledge and
familiarity with the terrain being mapped.
Many map items have been omitted. Other items have been simplified to a
considerable degree. In view of the map purpose much detail had to be represented
concerning special subjects and situations. This is especially striking for the seaport
and industrial sites. Factories, stores, oil tanks, piers and other items have been
represented as much as possible.
From the compilation and generalization of detail resulted a key line drawing which
had to be completed with supplementary up-to-date information gathered from
various governmental offices such as the State Waterboard, Hydrographical Service and
municipalities.
COLOUR SEPARATION
The key drawing on Astralon could be used directly as the original copy for plate
making. The line work was printed in sepia (see map). Subsequently as many blue keys
have been produced from the key drawing as there were printing colours, except for
the light grey colour of the various colours have been opaqued on the mat side of the
Astralon sheets. These drawings are mirror reserved, so they could be used directly for
plate making.
The next step involved the combination of all colour masks by contact copying on
one Astralon sheet. This finally gave a negative image of the light grey background. On
the translucent parts of this copy secondary roads were drafted and industrial sites
opaqued, because these details must remain white on the final map (open Spaces in the
background colour). From this negative a reversed positive was produced which
contained the background colour areas in black. Thus this copy could be used as a
diapositive for the making of the grey plate.
FINISHING
For the names on the map a type overlay was prepared on a translucent sheet. On
294 K.N.A.G. Geograßsch Tijdschrift VI (19721 Nr. 3
