Pinakryptol Yellow

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Was reading an old photo book by Neblett last night (1938) where he talked about Pinakryptol Yellow (also used in FX-2). The claim was that it had to be used as a pre-development bath, as the sulfite in the developer destroys it. Yet, it's a component of FX-2. I'm curious if it really does much, since I've forgotten to add it with no ill consequences. Also, if it works because it's added right when the working solution is mixed and doesn't have time to degrade. Or if Neblett is just wrong? Any thoughts?

-- Conrad Hoffman (choffman@rpa.net), February 18, 2002

Answers

Conrad, just a slightly educated guess; it might be a desensitizing dye that would improve one's ability to "develop by inspection".

-- Bill C (bcarriel@cpicorp.com), February 18, 2002.

Pinakryptol yellow is indeed a desensitizing dye. The FX-2 formula calls for it to be added after parts A and B of the formula are combined, just before development. I have read that it can be eliminated with many modern films. I believe it is still available from Photographer's Formulary.

-- Ed Buffaloe (edb@unblinkingeye.com), February 19, 2002.

Right y'all are, and I'm using the stuff now. What I can't determine is if it actually does anything. Leaving it out, at least with FP4+, doesn't seem to have much effect. Great combination, BTW.

-- Conrad Hoffman (choffman@rpa.net), February 19, 2002.

Conrad, its function in FX-2 is as a restrainer, so it should lessen fog. Supposedly with t-grain, crystal grain, and the other "modern emulsion" films it is not recommended. Why, I don't know. Perhaps they are less prone to fog. In any case, I've found, as you seem to, that using it or not doesn't seem to have much, if any, affect on any film.

-- Ted Kaufman (writercrmp@aol.com), February 19, 2002.

All the pinakryptol dyes are desensitizing agents (although there are some differences between them - some are destroyed by sulfite and have to be used as a forebath etc).

The purpose of pinacryptol yellow in FX2 is as a restrainer. Something about slightly better discrimination between exposed and unexposed grains, if I'm remembering Anchell and Troop correrctly. In my experience, it never made much of a difference. Its a pretty clean working formula. Cheers, DJ.

-- N Dhananjay (dhananjay-nayakankuppam@uiowa.edu), February 20, 2002.



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