Grainy stain

[psvensson]

I've heard that one of the main reasons for using a staining developer is that the stain "mask" or "veils" the grain, reducing apparent grain in highlights. I've also heard that the stain is "grainless," which would seem to be the reason it masks the grain. Apparently, old-timers used to bleach the silver out of pyro negs to get a grainless image.

I tried to put this to the test by making a strong hydroquinone-based staining developer, overdeveloping the hell out of a piece of Delta 400, then bleaching out the silver with ferricyanide. The result was quite disappointing: the remaining stain was very grainy, and not sharp either.

It would seem that the grain-mitigating effect of staining developers is something other than a "grainless" stain. Maybe the "grains" of the stain occur between the silver grains.

It's also possible that the test has no relevance to traditional staining developers that use pyro and catechol.

The developer was:

4g hydroquinone
10 ml phenidone 1% in alcohol
20g sodium carbonate monohydrate
1l water

15min at 75F

 

[Tom Hoskinson]

Good question! Replace the 4 grams of hydroquinone with 2 or 3 grams of catechol and try the experiment again.

 

[psvensson]

I'd love to, but I can't. My darkroom is also my bathroom, and I've promised myself to keep toxicity to a minimum. Maybe one of the pyromaniacs is up for it?

 

[avandesande]

Hydroquinone is as toxic(LD50 320 mg/kg) as pyrogallol(LD50 = 1600 mg/kg) or pyrocatechol(LD50: 260 mg/kg) . It also oxidizes more slowly and takes longer to decompose.
Hydroquinone also attacks the cornea and causes blindness...

I am not trying to scare you. Gloves and some common sense will go a long way.

 

[psvensson]

Yep, even hydroquinone is stretching it for me. My regular developer uses ascorbic acid instead. But after my girlfriend brought home a skin treatment that was 2 percent hq, I thought "what the hell." I did convince her not to use it, though.

 

[Tom Hoskinson]

Well, I am a certified pyromaniac and I do have stock solutions of hydroquinone, catechol and pyrogallol (all in propylene glycol).

What I don't have is any Delta 400. I do have HP5 plus and TMax 400...

 

[psvensson]

Try it with HP5! It might be the same gelatin as D400.

 

[psvensson]

Interesting experiment, Peter. I wonder if it's not grain you're seeing, but non-uniformity, or speckles like a halftone image? It seems very unlikely that a stain image could include grain, considering the silver has been bleached out. What would the "grains" be composed of?

Jay

I don't know. Maybe there's more staining around the silver grains?

 

[Donald Qualls]

It seems very unlikely that a stain image could include grain, considering the silver has been bleached out. What would the "grains" be composed of?

Given that what we see as grain in a print is actually the *interstices* between clumps of silver grains, where light passing through produces a black area on the print, it's very possible that what's reading as grain in a bleached, stained/tanned film is the interstices in the stain left by the removal of the original silver grains/clumps.

 

[gainer]

I never could see the logic of the grain reduction by pyro, but then I of all people should not be touting logic over experience. If the image stain were exactly the same size and shape as the silver grains that formed it, it doesn't seem that there should be any grain reduction, with or without the silver. The usual explanation is that the dye diffuses into the space between grains, but it may also be wishful thinking. It's too bad we can't as easily bleach the dye without affecting the silver image.

I know that pyro developers formulated to minimize stain are not noted for fine grain, but the sulfite added may have something to do with that. I know that seems to be heresy, but it is not really such unless the professed belief is true.

 

[Donald Qualls]

Jay, the image from a staining developer *could* be grainless, but it's unlikely the stain will ever be exactly the same density as a silver clump (and if it were, that area would print pure white, a "blocked" highlight). Rather, the density between silver grains acts (as has often been touted over the past century) to reduce the appearance of grain, because it reduces the intensity of the dark spots produced by light coming through the interstices.