Photo Litho Composing (Helio)

The department responsible for making printing plates ready for the printing presses has had several different names over the years – originally Helio (short for Heliozincography, the chemical process used). This was invented by Ordnance Survey’s former Director General Henry James in the 1800s (add further history/detail from the Wiki page). It was later known as Photo Litho Composing (PLC), Graphic Repro B (GRB) in the 80s/90s and finally Prepress. This page will refer to the section as PLC.

The PLC department was one step of the overall production process, taking negatives from the Photographic department, making printing plates and then passing to Printing/Proving.

Whirlers

The negatives were applied to zinc printing plates and then exposed to light using arc lamps originally but later other lamps.

Exposing lamps

Arc lamps were originally used for exposing printing plates once they became available with the advent of electricity in the early 20th century. By the time of the move to Maybush, arc lamps appear to have been made obsolete by safer alternative light sources.

PLC at Maybush

See this page for a lot more information specific to the PLC section at Maybush, as opposed to this page, which is more of a general overview.

PLC was located next to the Photographic department in the SW area of the William Roy Building (WRB), in the areas beneath the barrel-vaulted glazed roof.

Like with the Photographic area, computer-to plate (CTP) technology meant that one machine could do the work of the entire PLC area.

Computer-to-plate machine, 2010

Historic Helio

Prior to the move to Maybush in 1969, the Helio department was located in the Romsey Road Block of the temporary OSO Crabwood huts and also at London Road.

Graining

Graining was a process used to make used printing plates suitable for re-use. They were put in a vibrating tray with ball bearings with the intent of making their surface rough and suitable for adhesion of ink etc. There was a dedicated room in Services Block at Maybush for this, in the area later used as the facilities management offices. I’ve not seen any photos showing the graining at Maybush.

The graining workshop at OSO Crabwood was located near the driving test centre on Green Lane, separated from the main complex of huts.

Last updated on Thursday 9 January 2020 by GaryReggae