Reproduction (repro) is the process of producing a copies of graphics. In the 21st century, this can be done easily using, for example, inkjet/laser printing from computers. Before the computerisation of this in the 1990s, it was a meticulous task.
Maps were drawn or edited by draughtspersons in Cartography, then examined for quality control. Various different materials were used for this, from scribing on plastic to etching glass plates.
The completed map was photographed in the Photographic section using large room-sized process cameras. This produced negatives.
HPL Littlejohn Camera 1 at OSO Crabwood 
Monotype process camera 329C at OSO Crabwood 
Dai Nippon process camera in 1988
In the Photo Litho Composing (Helio) section, metal printing plates were exposed to light using the negative to mask out the image. After various chemical processes and washes then these were ready to be used as printing plates.
Exposing lamp 
Whirler 
The next stage was the Printing section. The plates from Helio were used on an offset litho printing press, either monochrome or using multiple colours. There was originally a separate ink for each colour to be printed but the industry-wide CMYK standard was later adopted.
Crabtree printing press at London Road, 1950s/60s. 
Crabtree Sovereign printing press at Maybush
The press printed maps on flat sheets of paper so these needed to be trimmed, folded and the cover attached. The covers were printed separately. This stage was known as Print finishing/Map Mounting.
Last updated on Wednesday 17 February 2021 by GaryReggae