Visible image stain, low general stain film/pyro combo

[cariocakev]

Friends,

For a demo in a university photo class I am looking for a film/developer combination that gives the highest proportional image stain and perhaps a relatively low general stain.

I'm not looking for something eminently printable, fine grain or for any fine finishing consideration. I simply want to have a LF neg that I can show students where the proportional image stain is visible to the naked eye.

Though much valuable stain for printing is often nearly invisible, I'm looking for the dramatic effect so students can see clearly what the stain is doing before then finding a good printing or scanning combo for themselves.

Any suggestions welcome, particularly from the serious alchemists out there (Mr. Leban, Mr. Wimberly, Mr. Hutchings, Mr. Moersch, Mr. de Fehr...).

Advance thanks!

[Doremus Scudder]

Although I'm not in the list of celebrities you mentioned, I have a couple of suggestions:

The more "traditional" films like the Efke, and BPF films will show a good amount of stain. I see a lot of stain with good old Tri-X as well as very low general stain. Identical negatives developed in a conventional developer, say HC-110 or D-76 and in a staining developer like PMK will show a marked difference with any conventional film. Less so with T-Max and Delta films.

As for demonstrating the stain image to your students, why don't you take a rather dense negative, even one overexposed a stop or two, and then bleach out the silver image. You can do this with a weak potassium ferricyanide and potassium bromide bleach right before their eyes in daylight (even in a glass tray on an overhead projector if you like...) The result is a fainter, but highly visible yellow-brown stain image. The silver in the image will have been changed into invisible silver bromide. This you can re-develop if you like (in a staining developer for even more stain...) or you can fix it out. All of this can be done in daylight and is therefore readily visible and really shows the relationship of the stained image to the silver image.

FWIW, I use the bleach/redevelop in PMK to add more stain contrast to weak negatives on occasion.

Hope this helps,

Doremus Scudder

[cariocakev]

Thanks Doremus!

The bleaching idea is quite intriguing. I'll definitely experiment. Do you have a solution percentage for the bleach?

Best,

Kevin

[Eric Woodbury]

The strongest, most visually prominent stain I've seen, is Wimberley's WD2H pyro developer with HP5+. I have only used it with HP5+, so I know not of other films with this developer, but when you see that neg, you know something is going on. It is very striking. It is more dramatic than PMK, pyrocats, and 510Pyro, without a doubt. Don't know of the others.

[Ken Lee]

One way to see the stain, is to make an RGB scan of a negative developed in a staining developer. Then, compare the histograms of the Red, Green, and Blue channels, with that of a monochrome scan.

You will be able to see the differences in graphical form - and if all or part of the subject is a step-wedge, it will be even easier to see where in the density curve, the stain gets absorbed most.

Pyrocat HD gives a brownish stain, which appears mostly in the Red channel. PMK is yellow-green, and thus appears mainly in the Red and Green channels.

[Jay DeFehr]

Hi Kevin,

I'm flattered to be mentioned in such distinguished company. In answer to your question; I think any staining developer will suffice for your demonstration. That being said, there are differences in the expense, complication, and keeping properties of different staining developers, and since just about any staining developer will do, I would recommend the simplest one, based on chemicals you have on hand. A perfectly serviceable staining developer can be made from pyrogallol, catechol, hydroquinone, or even instant coffee; although the latter does produce a lot of general stain, and is horrible to work with, in my opinion. A concentrated stock solution made up in glycol or TEA is very convenient to use, but not every darkroom stocks these chemicals. Almost every darkroom stocks hydroquinone, sodium sulfite, and sodium carbonate, from which a very demonstrative staining developer can be compounded. To keep things very simple, you could use it as a two-bath developer, with 1/4t hydroquinone and a pinch of sulfite/ liter as the A bath, and 1-2T/Liter sodium carbonate as the B bath. Develop 2-5 min in each bath. Substitute catechol or pyrogallol for the hydroquinone for different colored stains.

If you want to make the most efficient/economical staining developer possible, and you don't mind buying specialized chemicals, I recommend Hypercat:

A

Catechol 10g
Ascorbic acid 1g
Propylene Glycol to 100ml

B

20% sodium carbonate

Dilute 1:10:300 for normal developing times, with normal, intermittent agitation schemes. For rotary processing, Hypercat is best used as a two-bath developer. Dilute the A bath 1:25, and the B bath 1:2 (1+1), and develop 2-5 min in each bath.

Any of the above options will yield obviously stained negatives, and illustrate how simple a staining developer can be to make and use, and you might be surprised at the printing qualities of the negatives they produce.

Good luck, and have fun!

[Doremus Scudder]

Kevin,

The bleach proportions are not critical. I use anywhere from 5g potassium ferricyanide and 5g potassium bromide per liter up to 15g each. In the latter case, I save the bleach and reuse it.

If you are only going to bleach a few negatives, then try the weaker solution.

Best and good luck,

Doremus Scudder

[cariocakev]

Many thanks gentlemen.

Eric: I hadn't yet tried WD2H and will give it a go for general curiosity as well. That's the beauty of bulk chems.

Ken: Interesting scanning suggestion. I had considered a color densitometer (assuming I could borrow one somewhere at the U) to show off the change, but this would be simpler.

Jay: Love 510, by the way. Haven't yet tried Hypercat, and I shall. I already have the ingredients on hand. Thanks for the good work on all three of your devs! And I had forgotten about the "breakfast lab" developing fun. There could be an entertaining class session in that too. It offsets a common student perception that web labs are hard.

Doremus: Thanks for that suggestion. And very nice work on your site, by the way.