Magenta RA-4 Print from a Grey Studio Wall
A darkroom is making 8 × 10 inch RA-4 prints from a colour negative of a bride and groom against a neutral grey studio wall. The enlarger has a dichroic colour head with a 100 W halogen lamp. The first print, at f/8 for 8 s with 40M + 30Y filtration, shows a magenta cast in the grey wall and the bride’s white dress; the skin also looks slightly red. A grey-card negative exposed on the same roll prints magenta at the same settings. The drum processor runs at 35 °C with RA-4 chemistry replenished at 2%; the lab’s reference-negative control print is within tolerance but slightly low in contrast. The client wants 30 prints by Saturday; today is Thursday.
1. Decide whether the cast comes from the negative, the enlarger or the processor, and describe the tests you would run.
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The reference-negative control print is the key. If a known-good negative prints neutral at the current filtration, the processor, lamp and basic filtration are not grossly wrong. The grey-card negative from the same roll printing magenta then points to the negative itself - either the grey card was exposed under mixed or coloured light, or the film was affected by age, heat or development. The skin looking red is consistent with a negative that is magenta-balanced overall rather than with a random enlarger fault.
I would still separate the variables. First, inspect the negative base-plus-fog colour and density against a known good negative. Second, print the reference negative again at the same settings and confirm it is neutral; if it is not, check lamp voltage, dichroic filters returning to zero, and whether the filters are worn. Third, run a processor control strip to confirm the slightly low contrast is within tolerance and not drifting. A step wedge or a known neutral negative will show whether the cast follows the negative or appears only with this image. Only after those checks would I adjust filtration for the customer negative.
2. Give a filtration and exposure correction plan, explaining the direction of the correction and the compensation needed.
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The print is too magenta in the grey wall and white dress. On a subtractive dichroic head, adding magenta filtration absorbs green light, so the green-sensitive layer of the paper forms less magenta dye. I would therefore add magenta filtration, starting with about +10M from the present 40M + 30Y, and make a single test print. If the grey wall is neutral but the skin is still too red, I would not keep adding magenta globally; I would check whether the negative has crossed curves and make a small separate test, perhaps with a little more yellow or a slight cyan reduction depending on the direction of the error.
Filtration changes also change exposure because the filters absorb light. I would keep f/8 and make a stepped time test around 8 s - for example 8, 9 and 10 s - rather than changing aperture, filtration and time together. One variable at a time is essential. Once the grey wall and the white dress are neutral, I would compare the skin under the correct viewing light. The test print would be retained as the reference for the 30-print run, and the filtration and time would be written on the back of the negative sleeve.
3. What would you do about the slightly low contrast and the Saturday deadline?
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Slightly low contrast could come from developer temperature, development time, replenishment rate, or paper age. The control print is within tolerance, so I would not immediately alter the processor; I would first verify the actual drum temperature and the replenishment volume, then run another control strip. If the strip remains at the low end but inside tolerance, I would make the filtration test and judge the print visually. RA-4 paper does not offer contrast grades, so optical correction is limited; a scan-and-correct route may preserve more separation if the negative is flat.
With 30 prints due Saturday, the sequence matters more than speed. Thursday is for diagnostics and one test print; Friday is for the full run once the test is approved. I would not print 30 sheets on an uncorrected setup. If the processor fails its control strip, I would tell the client immediately and offer either corrected scans or a delayed print delivery, rather than send inconsistent colour. The lab should record the control strip, filtration and time so that any reprint matches the approved test.