Stain in Pyro developers

[Max Hao]

I have been reading the threads about Hypocat, and wonder whether the Hypo clear will kill the stain. BTW, I do like to keep it. Cheers.

[Jay DeFehr]

Hi Max,

No need for hypo clear with film. Best practice is: developer > plain water rinse > fixer > wash > Photo Flo > dry.

Good luck!

[Max Hao]

Many thanks Jay. Maybe I need to change the water now. I use a washing box which has a pump to create water flow, but the same 5L of water in the box.
BTW, I recently used 510PYRO. The sheet looks very thin, but surprisingly it scanned very well:) I think I'll stick with pyro developers for the sharpness and highlights.

[Jay DeFehr]

Hi Max,

How are you processing your film? Changing the wash water is critical. If the fixer that diffuses out of the emulsion has nowhere to go, the film will never be completely washed.

Stained negatives can look odd when one is accustomed to non-stained ones, and it can take some time to adapt. Likewise, it can take some time to become familiar with a new developer. With experience, you'll refine your process and have fewer surprises. I'm glad your first experiences have left you with useful images, and I'm sure it won't take long to get comfortable.

Why don't you post your results? I'd love to see what you're doing.

[cdholden]

Max isn't the only one losing pyro cherry. I made a batch of 510-pyro recently and hope to find time to get into it this weekend.

[Jay DeFehr]

Hi Chris,

If you've already mixed it up, the rest is even easier! If you don't have a measuring syringe, I highly recommend you get one. A 5ml size is very convenient. If there's anything I can help you with, feel free to contact me at:

jdefehr@gmail.com

[Max Hao]

Hi Max,

How are you processing your film? Changing the wash water is critical. If the fixer that diffuses out of the emulsion has nowhere to go, the film will never be completely washed.

Stained negatives can look odd when one is accustomed to non-stained ones, and it can take some time to adapt. Likewise, it can take some time to become familiar with a new developer. With experience, you'll refine your process and have fewer surprises. I'm glad your first experiences have left you with useful images, and I'm sure it won't take long to get comfortable.

Why don't you post your results? I'd love to see what you're doing.

Hi Jay,
I guess the water saving washing isn't paying off. I developed another roll today and did a few changes of water after washing in the box for 30 minutes, and I got much clean negative. I don't have PhotoFlo yet.
Since I don't have much time to shoot large format, I carry a medium format on my way to work. What I really need is a developer that goes well with ISO400 films.
I found Acros gets less stain than other conventional films say Tri-X. The Acros gets very very sharp in 510-PYRO, I wanted to water it down a little bit. I'll try it on some 4x5s and post the results. Cheers.

[Jay DeFehr]

Hi Max,

Acros is my favorite medium speed film. The stain is there, but it's bound closely with the silver, so it's not obvious. TMY-2 and 510-Pyro make a very nice combination (my favorite). Try extending development and decreasing agitation frequency.

A little about the appearance of stain:

I often read comments about this or that film not staining as well as others, or that my developers don't stain as much as other staining developers, but in my testing I see something quite different. 510-Pyro and Hypercat II are very clean working developers, meaning they produce almost no general stain, and this is by design. General stain is a non-proportional dye mask very similar to fog. Fog results from non-selective development of silver; in other words, parts of the film that were not exposed get developed to an even density across the entire film, and acts like a neutral density filter in printing. General stain is analogous; it is an even dye mask over the entire film, just as if a colored filter was placed over the negative. Since general stain is a different color than the silver, it's easy to see it where there is no silver to block the light transmission through the negative, ie in the low values and base. So a negative with general stain looks more stained than one without, but that stain is not useful, except to extend printing times. Stain is useful precisely because it is proportional, and so there should be none where there is no silver density. The effects of fog and general stain are cumulative, because a staining developer will stain silver fog, so it's vital that a staining developer produce no fog.

I developed a simple method for measuring proportional stain, that doesn't require a step wedge or a sensitometer, but it does require a color densitometer. The film to be tested must include a patch that has been exposed sufficiently to produce Dmax, and another patch that has not been exposed. The test film is developed to completion in the selected staining developer, then fixed and washed as normal. Both patches are read in Visual and Blue, and the visual subtracted from the Blue. Then the Low Blue is subtracted from the High Blue to give the Net Stain, or Proportional Stain. The data set looks like this:

LDB (Low Density Blue)
LDV (Low Density Visual)
HDB (High Density Blue)
HDB (High Density Blue)
LDB - LDV = LDS (Low Density Stain/ General Stain)
HDB - HDV = HDS (High Density Stain)
HDS - LDS = Net Stain

And the stain proportional to the silver can be calculated for any silver density by:

DB/DV = Stain proportion

By calculating stain proportions at different densities, a Proportional Staining Curve can be plotted for a film/developer combination.

When formulating a developer, this test can help to find the best compromise between highest overall stain, as measured by HDB -HDV, and lowest general stain, as measured by LDB- LDV. And it can be useful when comparing staining developers, or films. When I was formulating my staining developers I generated a lot of these tables and curves.

There's more to a staining developer than the stain, but stain is a primary characteristic, and so deserves special consideration, but we must keep in mind how stain interacts with other developer characteristics to achieve overall Image Quality, which is the end goal of any developer, as well as keeping, handling, economic and other characteristics which don't bear directly on IQ.

Every developer formula represents a set of compromises designed to produce a desired set of characteristics according to a hierarchy of preferences and priorities, which is why slight variations in formulas can produce significantly different developers, and why it's so hard to improve any good formula without changing its character. I think 510-Pyro could be improved, but probably not by me. I simply lack the chemistry background and facilities for the kind of analysis that would likely be required, and I think it's a little late in the day for anyone qualified, with facilities, to invest their time/resources on such a project. Happily, I can live with 510-Pyro as-is!

Have fun!