Why Dilute Selenium Toner at All?

[Andre Noble]

Hello,

Take stock Kodal Selenium toner for instance. It is frequently diluted 1+3 to 1+9 or more.

However, the other day I used it at stock strength to tone some Adox MCC 110. I like the deep purplish brown tone, and the prints look grat, and I was able to pout the toner back into the original Kodak bottle.

Aside from the stronger fumes, what are any down sides to using stock strength selenium toner which I am not aware?

[Andre Noble]

Or rather I should say, deep maroon (not purple) browns it produces with Adox MCC 110

[DanK]

I'm not aware of any additional hazards with using the product at full strength...beyond that the product is full strength...and normal precautions should be used...

I would advise against returning the 'used' solution to your original container, as it will contaminate the unused solution....reducing the usable life overall...

I'd probably suggest extended washing times for the prints toned with full strength toner.....I wash 90 minutes after toning at 1:20 with kodak rapid selenium...

Also, increasing your time in a diluted toner, may realize similar effects....and would extend the life of your toner....

Thanks,
Dan

[Drew Wiley]

The rate of toning is much easier to control dilute (I dilute 1:20 always), and it's much more cost-effective that way, unless you want progressively unpredicatable recycled toner.

[Andre Noble]

Dan and/or Drew: at 1:20 dilution, do you feel you get complete conversion of the silver (eventually) in the print?

When I ran stock strength Selenium toner, I could see the silver conversion happening before my eyes, so I got an intuitive sense of the process as a chemical conversion similar to putting an exposed paper into developer. The visualization made me feel that selenium toning (for archival purposes at least) should be a process that is run to completion.



I guess others tone with dilute selenium for partial color shift, and uniformity.

[DanK]

Dan and/or Drew: at 1:20 dilution, do you feel you get complete conversion of the silver (eventually) in the print?

When I ran stock strength Selenium toner, I could see the silver conversion happening before my eyes, so I got an intuitive sense of the process as a chemical conversion similar to putting an exposed paper into developer. The visualization made me feel that selenium toning (for archival purposes at least) should be a process that is run to completion.



I guess others tone with dilute selenium for partial color shift, and uniformity.


Andre,

I honestly can't answer whether the conversion is complete at any concentration, from what I understand the process only partially converts the silver present to silver selenide - I believe it attaches/reacts to the surface of the silver...but am by no means a chemist...

The papers I generally use show minimal, if any, effect from the toner (Oriental FB Cold Tone and Ilford MG FB) - I perform the toning step for permanence, with slight detail increased in the shadows on both papers at the 1:20 dilution.

Thanks,
Dan

[Drew Wiley]

It doesn't take a lot of selenium to significantly enhance the permanence of a silver
print. But another major reason for using it is to fine-tune the final hue of the print.
This can be done by any combination of concentration/time/temp you choose. Some
papers tone faster than others. And it is difficult to stop the toning process instantly.
(I rinse the print under a hose). Then if you add the effect of still different toners, the
cumulative result might not be apparent at first. In other words, I like a slower regimen of toning so I don't go overboard. The toning characteristics of MCC are not among my favorite, although I like this paper quite a bit for other reasons, at least with certain images, if not for others. Just experiment with different dilutions and
times, to see what effects you like.

[Oren Grad]

It doesn't take a lot of selenium to significantly enhance the permanence of a silver print.

How much is "not a lot"? How much is "significantly"? What evidence supports this?

[Drew Wiley]

Oren - you're pretty much getting into the field of art conservation here, along with all the ramifications of the kind of fixer, how well a print is washed, the kinds of atmospheric pollutants involved, etc. Too big a subject. Let's just say that prints which were selnium toned, regardless of whether a significant color change ocurred or
not, seem to have survived much better than ones which weren't, given the law of
averages. I think this is pretty well accepted in art conservation circles and doesn't
need a lot of elaboration here. Might make a nice phD thesis for an aspiring photochemist, however.

[Oren Grad]

Drew, if you ask conservators for objective, quantified, controlled data on this, you will have a very hard time finding any who can provide it. The one thing that can be said is that data from a number of sources in recent years have conclusively demolished the old dogma that light toning in selenium is fully protective.

Here's some relevant information I posted a good while back:

http://www.largeformatphotography.info/forum/showthread.php?t=13859