Dufaycolor to Ilfochrome

Alf Pyner

Alf Pyner has 63 years experience in photography. He joined Ilford Limited after his time in the RAF during WW2 and had a long association with Ilford’s experiments to develop colour materials. As their lab processor of emulsion test strips he became involved with all scientific aspects of film production within the test facilities.

Ilfochrome - a colour print process from the 1960s that creates the colour positive directly from a colour slide using AZO dyes imbedded in the print emulsion. The development process bleaches out the unneeded dyes to create a very sharp image with excellent archival qualities. Known as CibaChrome after CIBA-Geigy bought Ilford in the 1960s and now again as Ilfochrome (sometimes known as Ilfachrome as this 1960 sample was markd on the back).

Ilford Limited - A small collection of British companies merged in the early days of photography forming in 1879 the Imperial Dry Plate company in a suburb of London, England. The plant and studio in Ilford near the high street (main street) became the home of Ilford, Limited. Beginning in 1946, the company published the Ilford Manual (the first edition had no photos).

Alf began working on creating colour photographic materials for Ilford in 1946 using a home-made densitometer to test negatives. The first products were based on the Agfa-Gaevart colour processes seized after WW2. He noted that standard daylight colour temperature was set as noon sunlight in Washington DC. In 1950, Ilford made a computer to calculate the various functions relating colour to the composition of films. The photo montage to the left is a collection of Ilford Limited memories. Two show Alf with fellow researchers.

He taught a series of one week courses training Ilford staff in the theory of colour and colour printing. He was later chosen to enlightened the press, professional photographers and the public in the technical aspects of processing Ilford colour films and papers. He used the 50 year old slides in this talk to recap colour theory, explain how the human eye sees colour (with the help of pink elephants), effects of dim light on colour vision, white balance compensation and the need for daylight and tungsten versions of colour materials, additive vs subtractive colour systems, problems with dye purity and the need for an orange filter, etc.

Alf covered the highlights of colour photographic materials beginning with the Dufaycolor matrix process up to the creation of Ilfochrome. Alf chose Dufaycolor to demonstrate the additive colour process known from the days of James Clerk Maxwell’s colour experiments in the mid 1800s. He then covered the modern day tri-pack colour materials which combine three colour sensitive layers on one base along with various compensating layers and filters. He noted the difficulties of selecting the right emulsions and dyes to create the desired result. Tri-packs use three black and white emulsions to capture the light values in three colours. Processing then creates the appropriate dyes and densities. The colour couplers - which react with the development products to create the dyes - can be in the emulsion (Agfachrome, Ektachrome) or in the developers (Kodachrome). Putting them in the emulsion limits the choices of colours and stability while putting them in the developers makes the process too complicated to do outside of a factory.

Alf explained that a computer was used to calculate the various dye/silver combinations using matrix algebra, with corrections for impurities and the colour sensitivity of the dyes. He made test strips by hand using a small coating machine to confirm the image qualities of each test film.

He noted that in addition to the colour sensitive layers, the films had an anti-scratch top super coat and an anti-halation backing layer. He explained that the common orange look of colour negative materials was due to a filter layer added to compensate for the magenta dye layer being sensitive to other colours.

Alf noted that in creating a popular colour material, the manufacturer has to take into account the tastes of the consumer. The public prefers saturated colours over an accurate rendering of the original scene. The most important factor is to render attractive skin tones.

The Ilfochrome process creates colour prints directly from colour transparencies. This results in much sharper images than possible with the colour negative process. The Ilfachrome material is very contrasty. It uses a dye destruction process and the dyes imbedded in the material are very stable creating accurate saturated colours with archival qualities. Ilford spent a year on Ilfochrome, first to get a working version, and then to tune the colour quality and other characteristics. The process uses a strong acid which has to be neutralized before being discarded.

Today, over forty years later, Ilfochrome is still used by many photographers to create archival quality colour prints. Do a Google search on Ilfochrome or Ilfachrome to find some of the people offering Ilfochrome prints. Visit the Ilford site for process specifications, and the Image Designs site for further descriptive information.

Alf ended his talk with a selection of very old slides made with Ilford colour materials, He included a thermometer slide that shows the slide gate temperature.

Nb - Alf confessed at the end of his presentation his real love is making traditional black & white prints, especially those of working boats and the sea.

The images shown on this page were taken during the presentation with a Nikon Coolpix 990 and adjusted and sized in Photoshop. Most were snapped directly from the screen and suffer a loss of detail as a result. Please do not use the images without the permission of Alf Pyner. You can contact Alf via

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