Colour darkroom printing

In looking for more imaginative ways of making photograms in the darkroom, I have been exploring the possibility of creating them in colour using 'C' Type papers and RA4 chemistry. As a result of the panchromatic nature of colour materials, the practicalities of colour printing are more complex than monochrome printing with silver gelatin processes. The papers need to be handled in total darkness (no safelight). They degrade quickly if not stored correctly and the chemistry also needs to be fresh. The processes  require higher temperatures for the chemicals which need to be tightly controlled, especially the colour developer (to plus or minus 0.5 degrees). Although black and white darkroom papers can produce interesting results even when many years out of date, after several completely unsuccessful  attempts to produce an image, I have learned the hard way that this does not work with expired colour chemicals or with colour papers which had been stored for several years. Having obtained a new box of Fujicolor Crystal Archive paper and Tetenal RA4 chemistry, I have finally managed to make some test prints which have strong bold colours and am hopefully about ready to start making some new images.colour-wheel-(1-of-1)Getting to this stage proved more challenging than initially expected and I found it difficult to think in terms of inverted colours as well as inverted tones. For example, correction for a yellow cast in a print, requires the addition of its' complementary colour i.e. blue (Fig 1. above). The colour produced on the print is however the inverse of colour of the light projected on it so confusingly, to correct a yellow cast it is necessary increase by filtration, the amount of yellow emitted by the light source (see Fig. 2 below). When researching this I realised with regret that I had thrown out all my basic "how to" photography books which at the time seemed redundant but would have contained all this information. I also discovered that in most of the current versions of these books available in the college library, the sections on colour printing in the darkroom have been largely replaced with information on digital imaging but I found a limited amount of what I needed in "Langford's Advanced Photography" (8th Edition).Colour-wheel-Langford-201902111--EditOut of the box, colour papers have a cyan coloured coating on the surface which acts as an anti-halation layer and presumably at least partially corrects for the orange mask present on the surface of most colour negative films. My plan is to attempt to make colour photograms and am not using negatives so the cyan coating produced a very strong reddish brown cast on my initial tests (Test print 1) and after experimentation  I found that much stronger yellow and magenta filtration than anticipated was needed to achieve anything close to neutral greys (bottom (R) image on Test print 7).Test print colour001Test print colour003Test print colour002In the process of reaching a reasonable approximation for the basic colour filtration required for neutral tones, I have discovered that it will be possible to produce a wide range of both bold and subtle colours which potentially offer exciting possibilities for the work I am hoping to create. This is will undoubtedly involve more experimentation and although the element of serendipity is often useful in producing photograms, in addition to fine tuning the colours utilised, I will need to develop a technique for getting the objects used into the optimum position on the paper in complete darkness before making the exposure. The image below, my first crude attempt to produce a colour photogram, shows some of the visual potential of the technique, while demonstrating the need to tackle the issue of alignment of the objects on the paper.Photogram colour plastic001 Reference: Langford M and Bilissi E,  'Negative/Positive Colour Printing' In: Langford's Advanced Photography (8th Edition) pp 296-301. Focal Press (an imprint of Elsevier), London, 2011.