Do films developed in PMK need cold light? : LUSENET : B&W Photo - Film & Processing : One Thread

I understand that PMK developes on the surface and uses dye. Would this mean that the need for a cold light is not needed as it is for traditional developer/films? Does it behave more like XP2 in the enlarger?

-- John Kilmer (, August 13, 1999


PMK has a tanning action and a staining action, there are no dyes, you can use any light source you want, Edward Weston used a 60 w light bulb with toilet tissue wrapped around it. I use a Zone VI cold light for reg. papers and a 65 w black light for Azo papers. Pat

-- pat j. krentz (, August 14, 1999.

Like with any other film/developer combo, you must calibrate your exposure and development to your enlarger light source. If you use a cold light head, you can develop your film to a slightly greater contrast range. The pyro stain will inhibit some wavelengths of light (typically blue), so it may throw your filtration off slightly for variable contrast papers, but this is usually not a problem--you can adjust developer or development time, if necessary. The stain also enhances contrast, so pyro negs are often thinner than conventional negs, but still print normally. You can see through even the darkest areas of the pyro neg, assuring printability and separation in the high values.

-- Ed Buffaloe (, August 14, 1999.

If you want to produce the very best 'fine' prints, you should use a cold light for ALL negatives. See information on 'Callier Effect' in AA books and other sources. However, if you are stuck with a condenser enlarger, PMK negs will produce superior prints. This is because approximately half the image density is made up of stain (NOT dye!) instead of silver grains and therefore will reduce substantially the Callier effect. But this is only one of countless reasons to use this extraordinary developer.

-- Michael D Fraser (, August 20, 1999.

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