All the questions about Pyro and Chromogenic films like XP2 have set me thinking (dangerous!). }:^)

There seems to be no reason why a colour coupler can't be introduced at the developing stage for any black and white film, to give a stain like Pyro, but without the variability.

Are there any Chemists out there who could name a few substances that colour-couple with PPD derivative developers, to give a red, yellow or neutral stain? How easy are they to come by? Cost, toxicity, etc?

Thanks.

-- Pete Andrews (p.l.andrews@bham.ac.uk), March 29, 2000

Answers

If I'm not mistaken, that is pretty much the way the Kodachrome process works. This kind of question needs to be addressed to Robert Chapman of Photo Techniques magazine--he's the only person I know of who could answer it authoritatively.

-- (edbuffaloe@unblinkingeye.com), March 29, 2000.

That's exactly how dye transfer color prints work. The separation negs are developed in a tanning developer and then dyed. The dye "takes" in relation to the depth of the tanned image. Kodachrome uses the same principle, only it does it all on one film base.

-- Tony Brent (ajbrent@mich.com), April 02, 2000.

Tony -- one small correction: the matricies, not the seps, are developed in tanning developer. Then the 3 dyed "mats" are rolled onto a receiving sheet, one at a time.

http://www.ravenvision.com/peterhughes.htm

-- Peter Hughes (leo948@yahoo.com), April 02, 2000.