Pinakryptol yellow in FX-2

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What is the role of pinakryptol yellow in FX-2 formula? Is there any substitutions? Can I make it without this ingredient?

regards Xosni

-- Xosni (xosni@gega.net), October 04, 2001

Answers

It's purpose is an antifogging agent. Therefore, you can probably substitude potassium bromide or benzotriazole. I do not believe, however, with modern films you need any antifogging agent in this formula. Try making a batch without pinakryptol yellow and see if you get fog. If you don't, you're home free.

-- Ted Kaufman (writercrmp@aol.com), October 04, 2001.

I use FX-2 as a primary developer- Newer T-grain and similiar films (acros, delta)don't get the pinacryptol(no k) yellow. Use it with Tri- x, Neopan 400, etc. Otherwise, yes fog can result.

-- Mike DeVoue (karma77@att.net), October 04, 2001.

Pinacryptol yellow is more than a simple restrainer. It's one of a group of dyes that act as desensitising agents. In other words, it reduces the film speed, and makes the film non-panchromatic and insensitive to red light.
Whether the intention was that FX-2 was to be used for development by inspection, I don't know, but that's generally the use to which PY is put.
The effect isn't immediate, but I imagine that you could examine a film developed in FX-2 by a red safelight after a few minutes immersion.
Substituting the PY with a simple development restrainer would take away this ability.

-- Pete Andrews (p.l.andrews@bham.ac.uk), October 05, 2001.

The amount of pinaktriptol yellow (a former AGFA brand name for the dye) stated in the receipe is by far not enough to desensitize the film enough to make it possible to develop by inspection. On the other hand: By blocking the long red wavelengh you might get sharper images. Red is a real problem in photography, in colour and B&W and many different approaches have been found to compensate for example for the focus shifts that occur in the lens and on the film. The idea by Goeff Crawley could have been to desensitize the red spectrum enough so that the dominating blue spectrum could be recorded with maximum acutance without interference from the red wavelength. This would have to be tested.

-- Volker Schier (Volker.Schier@fen-net.de), October 05, 2001.

But the films is sensitised before applying Pankryptol!? The red spectrum is already recorded there.

But this is a really new concept to me. By the same rationale we could assume that using a blue filter (or blue flashlight) can render sharper image?

Is there any alternatives to this dye?

Thanks

-- Xosni (xosni@gega.net), October 05, 2001.



You are probably right about film, since the red spectrum is present during exposure, I did not think about this. On the other hand the blue filter -- at least theoretically -- is not such a bad idea if one would want to get rid of some chromatic aberation from the lens. A lens is corrected for two wavelength, an apochromatic lens has additional correction for a third wavelength, the longwave red spectrum. Reducing the red sensitivity using filters could add some sharpness. Orthochromatic films achieve the higher sharpness due to the fact that they do not have to record the red spectrum.

-- Volker Schier (Volker.Schier@fen-net.de), October 05, 2001.

Pinakryptol was introduced by Konig and is a family of dyes - the formulary sells yellow, green and white versions. Green is said to be the least effective, can cause staining with some MQ developers but can be used as either a forebath or mixed into the developer. Yellow is more active in reducing panchromatic sensitivity and more compatible with MQ developers but can only be used as a forebath as it is destroyed by sulfite. White is used in the developer. Pinacryptol is probably preferred to older desensitizers like Scarlet N, especially for modern emulsions. Olders desensitizers also tend to stain film.

With regard to FX2, the story in The Film Developing Cookbook is that Crawley found that PY offered somewhat better discrimination (than conventional restrainers and anti-foggants) between exposed and unexposed grains. Apparently, he also suggested that it should not be used for T grain film. So, it sounds like it has restraining properties in addition to the desensitizing property when used as a forebath.

Cheers, DJ.

-- N Dhananjay (ndhanu@umich.edu), October 05, 2001.


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