Selenium toner as negative intensifier

[Mark Sampson]

I remember reading some years back about the practice of using selenium toner as a negative intensifier. As I recall, the general wisdom was that doing so would give you about one-half paper grade's worth of increase in contrast.
Recently I made a negative or two that could use such a treatment. Of course, any explanation of the exact method is lost in the mists of time (which are rather thick at my house these days).
I could just try printing on higher-contrast paper, but I have two identical negatives, so I can experiment with one.

Then, in a recent thread, someone has pointed out that selenium toner removes pyro stain from developed negatives. Never heard that before, but perhaps I haven't been paying attention.
Since my film is developed in Pyrocat-HD, it sounds like intensifying the neg in KRST would be counter-productive.

So:
Can anyone explain the accepted method for intensifying negatives in selenium toner?
And:
If you've observed the destruction of pyro stain, by the use of selenium toner as intensifier, can you explain further?

[Vaughn]

With non-pyro negs, I use a strong dilution of Selenium toner, 1:4 (give or take) with water or HCA. If one uses a white tray, one can see the progress of the toning...or in my case I go a little longer after seeing no more density being added. Then wash. That method also seems to be one that might also reduce the stain if using pyro negs, unfortunately.

Before selenium toning, I will often bleach the neg lightly if the shadows can stand it. Since I contact print, I do not mind the deepest very small shadow areas going clear on most negs. Used together, I can get a nice bump in contrast that works well with my alt processes when I have a well exposed negative that is shy of my contrast target.

[Pere Casals]

See Darkroom Cookbook page 86 https://silveronplastic.files.wordpr...er-2008-ww.pdf

IMHO you should use paper calibrations as described in Beyond The Zone System book.

At the end a sensitometric straight line can be obtained from VC papers, the challenge is to compress highlights and shadows as we want, while allowing a range for the mids. This is always enlighted by calibrations.

What I do (in my learning process) is prototyping in Photoshop to understand how I want to bend the curves in the toe/shoulder, then by checking the calibrated curves one has an straigth path to obtain what one wants. This is before working on local exposure/contrast if the print demands that.

My view is that toning the negatives has alternatives for printing, but I consider it to adjust BW slides, I was working a lot with BW slides but still I was not satisfied with results, and I was considering adding some selenium to the process.

[John Layton]

Mark's query is mine exactly. I, too, have a couple of pyrocat hd negatives that I'd like to intensify with selenium - but am hesitant to lose the stain. These negatives are well exposed, and even perhaps a bit dense, but low contrast - would be perfect candidates for a bit of selenium...as has been my experience with heavy(ish), but flat, HC-110 negatives.

If anyone can chime in here...that would be great. Otherwise, I'll just find some reject negatives (got loads of those!) and do some tests.

[Pere Casals]

I'll just find some reject negatives (got loads of those!) and do some tests.

John, while testing with real images it's absolutely worth, I think that the best way to make a meaningful test is taking a T2115 stouffer wedge, making several identic contact prints (showing all density range) and toning all the strips but one with different dilutions/times.

This will tell how each original density ends in a toned density for a given toning process. And this will allow to make the most suitable toning in every case.

For all that we need a densitometer, but we can always use the scanner as a densitometer, just scaning (with all modifiers disabled) our sample alongside with the stouffer wedge and comparing values.

[Doremus Scudder]

Mark's query is mine exactly. I, too, have a couple of pyrocat hd negatives that I'd like to intensify with selenium - but am hesitant to lose the stain. These negatives are well exposed, and even perhaps a bit dense, but low contrast - would be perfect candidates for a bit of selenium...as has been my experience with heavy(ish), but flat, HC-110 negatives.

If anyone can chime in here...that would be great. Otherwise, I'll just find some reject negatives (got loads of those!) and do some tests.

John and Mark,

I used selenium intensification for negatives developed in non-staining developers for years with great success. Both local and overall intensification are possible (but you have to be careful with local intensification or you'll get halos...). I used KRST at 1+2 dilution and treated the negatives for 5+ minutes, the object being to intensify (tone) the negative to completion to get the most boost. The resulting intensification is proportional, i.e., more intensification in the denser areas of the negative, less in the less-dense areas, and, for me, corresponded to about an N+1 change in contrast.

When I started using staining developers (PMK), I found that the selenium treatment removed the image stain, effectively negating the effect of the intensification (they just about balanced each other out). I'm not sure what will happen with Pyrocat-developed negs, but I suspect that the stain will get removed as well. You'll have to test.

For easy intensification of PMK negs I now use bleach/redevelop. It's easy and can be done in daylight/white light. Use a rehalogenating bleach of potassium ferricyanide and potassium bromide (Caution: without the bromide, you'll bleach the negative irretrievably!)

For bleach/redevelop, it is critical that you completely rehalogenate the image forming silver (hence the bromide). The chemical amounts just affect the time it takes to accomplish this. I use:

15g potassium ferricyanide
15g potassium bromide
1 liter of water

...or similar proportions in a smaller amount. I've got a bottle of the mix that I keep on hand; shelf life is very long.

My method:

I presoak the neg in a tray of water for 3-5 minutes, then transfer to the bleach tray. I bleach until the image is completely gone and only very faint stain image remains. I then rinse quickly in the soak tray and then redevelop in PMK (you could use the staining developer of your choice). The redevelopment restores the silver image and adds another layer of stain, which is the intensification. I get about N+1 from this plus sometimes gratifying intensification of shadow detail.

Hope this helps,

Doremus

[Mark Sampson]

Thanks, gents. That's one of the things this forum is good for- deep looks into obscure corners of photographic practice.
I'll try printing one negative as-is. That will help me decide if heroic methods are necessary. We shall see!

[Pere Casals]

The redevelopment restores the silver image and adds another layer of stain, which is the intensification. I get about N+1 from this plus sometimes gratifying intensification of shadow detail.

What I feel interesting is that the redevelopment can be done lights open, so we can stop it when we see we have what we want. Perhaps doing it at lower temperature/strength may give time to allow a better control.

If redevelopment was not made to completion then film would need to be fixed later...

[John Layton]

Doremus...perfect! Thank You!

[Doremus Scudder]

Doremus...perfect! Thank You!

My pleasure!