COMIC computer


This fantastic piece of equipment looks like it’s come straight from the set of a 1950s science fiction B-movie. With its tiny oscil­loscope screen and seemingly hundreds of dials, switches, buttons, lights and meters this machine attracts plenty of attention from visi­tors to the SDC Colour Experience. Its official title is a Davidson and Hemmendinger 1958 Colourant Mixture Computer, but it’s gener­ally known as the COMIC. COMIC was the first analogue computer for predicting dye recipes to create a desired colour.

People have been colouring clothes for thousands of years and for most of that time they used colours from the natural world. They extracted colours from plants, insects and even shellfish. With the range of colours available it was often necessary to mix dyes to create a desired colour. Even with the advent of synthetic dyes in the latter half of the 19th century most colours were still formed from a mixture of dyes. The original methods of creating these dye recipes were based on the dyer’s individual experience and knowledge. Meticulous records were kept of each mixture or recipe along with dyed samples of the col­our that they created. These dyers’ notebooks would then be used as a reference or at least a starting point to create a new recipe to meet a customer’s specifications. Many of these notebooks have survived and are a wonder­fully colourful and informative record of a bygone era.

COMIC computerFor the vast majority of the time that people have been colouring their clothes colour matching was not a critical issue and if it was considered important then it would be done by eye. As colour consistency became more important towards the end of the 19th century ways were being explored of accu­rately measuring colour. The first successful colorimeter was actually developed in 1885 to assess the quality of beer through its colour. Joseph Lovibond worked in his family’s brew­ing business and realised that coloration was a good index for assessing the quality of beer. His colorimeter used carefully coloured glass samples to enable accurate colour assess­ment. Similar devices remained in use until the relatively recent intro­duction of photoelectric colorimeters and, later, spectrophotometers as more advanced colour measurement devices.

By the 1950s the time was right for a move towards dye recipe prediction. Henry Hem­mendinger, a graduate of Harvard and Princeton and former US Navy submarine researcher, became interested in colour measurement through his work at General Aniline & Film Corporation. Along with his colleague Hugh Dav­idson, Hemmendinger introduced, in 1958, the first automated colour matching system – the COMIC. Using the COMIC meant that instead of spending several days matching a colour in the laboratory through repeated test dyeing, an accurate recipe could be produced by adjusting controls within a matter of minutes.

The COMIC computer used the information from a tintometer, colorimeter or spectropho­tometer to calculate a dye recipe to create a specific colour. A customer would visit a dye­house or dyestuff manufacturer with a sample of the colour to be matched. The colour of the sample would be measured using one of the devices mentioned above which would pro­duce a set of 16 figures corresponding to the reflection of light across the spectrum. The numbers obtained from measuring the colour of the sample were set on the 16 dials at the top of the COMIC control panel.

COMIC computerThe COMIC technician chose three or more dyes which they thought would give a match and plugged the analogues of these dyes into the spaces on the right. These were electri­cal resistance boxes which were adjusted to mimic the spectral properties of the dyes. The small cathode ray tube showed sixteen dots whose vertical position indicated the differences between the initial sample and the mixture. The technician then adjusted the concentration controls in the centre until the display screen showed the 16 dots in a straight line across the centre. When this was achieved the operator read off the concen­tration of each dye to give the match from the central controls. Sometimes the match was not good enough. If this happened the COMIC was used to obtain a better match by measuring the colour of the new sample and setting the lower 16 dials and again adjusting the concentration of each dye.

In 1965 Radifon produced a British version on the COMIC which incorporated a spectro­photometer. This meant that the data from the sample was fed directly into the computer rather than the technician having to translate the readout into the settings for the COMIC.

The advent of digital computers brought great advancement in the field of colour measurement and recipe prediction and equivalent machines are now handheld; with its Bakelite dials, glowing valves and simple green screen display the COMIC seems to come from another age.

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