Why does selenium toner tones shadow area first? I am confused.

Discussion in 'B&W: Film, Paper, Chemistry' started by tkamiya, Apr 10, 2012.

  1. tkamiya

    tkamiya Member

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    It is commonly said that selenium toner affects the shadow first where as brown and sepia toners affect the highlight first.

    I can understand the latter. Highlight area has less silver so less time is required to finish the toning process to completion. But I have trouble understanding the first.

    Saying "shadow area" is the same thing as silver rich area. That would mean any attempt to tone it will take longer, I think. Then, why would selenium toner tones this silver rich area first while leaving highlight area largely untouched? If I did this, wouldn't selenium toner tone lightly silvered, highlight area to completion rather quickly?

    If I are to split tone, my (corrected) understanding is to selenium tone first, then sepia/brown. How does the selenium toner *knows* to leave the highlight part alone? Wouldn't that part tone to completion first?

    Please help this highly confused darkroom guy....
     
  2. Vaughn

    Vaughn Subscriber

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    Shadows have more silver for the selenium to react with -- thus more of the differently colored selenium/silver compound gets formed and thus the color of the shadows is more pronounced. Less silver in the highlights -- less of the selenium-silver compounds formed thus weaker color change.

    With sepia toning it is more has to do with the percentage of silver being bleached -- highlights get total bleaching (not much there to bleach), the shadows often only get partial beaching, unless one bleaches all of the image away before going into the Part B.

    The last part -- selenium reacts with the silver components in the print -- but does not react much with the silver sulfated compounds created by sepia toning which are very stable. I believe one can do it either way -- I have heard mostly of sepia toning then selenium toning. I will be trying this this week -- with prints very lightly bleached then sepia toned -- then selenium toned. (Forte paper).

    Disclaimer -- I am not a chemist...this is just my limited understanding of the processes going on.
     
  3. tkamiya

    tkamiya Member

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    Thank you.

    I understand the shadow has more silver to react with selenium. Let's say my shadow has 10 silver and my highlight has 2 silver. Let's also say every minute, selenium toner can tone 1 unit of silver. If I toned this print for 4 minutes, shadow has toned for good amount (shadow tone first) but highlight has toned to completion 2 minutes ago leaving nothing for the second toner to react with.

    Even if I changed the numbers around a bit, it still end with the same conclusion that highlight will reach toward the maximum toning (completion) first. If this is the case, how would one split tone anything?
     
  4. MattKing

    MattKing Subscriber

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    Just musing a bit here - I don't know the exact mechanism.

    Your scenario is based on an assumption - that the rate and amount of toning is linear and independent of how much silver is available for toning.

    If the toning rate is non-linear (logarythmic?), and based on the concentration of silver available for toning then the assumption is incorrect, and the amount of toning may very well be much greater in those areas that have a lot of silver available.
     
  5. tkamiya

    tkamiya Member

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    Yes, I made an assumption that the rate of change is linear - for sake of simplicity. But... does the rate of change itself really matter? Smaller amount of material vs. larger amount of material. In given time span, the reaction with the former will be completed or be closer to completion (percentage wise) than with the latter....

    The "amount" is not assumption though. Darker the image, more silver. Lighter the image, less silver.
     
  6. tkamiya

    tkamiya Member

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    By the way (totally unrelated to this thread), it was a happy day for me today. I spent a quality time in my darkroom! Yay, silver....
     
  7. Guillaume Zuili

    Guillaume Zuili Subscriber

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    The toner doesn't know anything. You know or you feel it and you remove the print.
    That's why there are good days and bad days in darkroom :smile:

    Split tone is usually sepia first then selenium. Sepia tones only what you have bleached. So you deal with the highlights first.
    Rinse and then selenium.

    If you do selenium first you have 2 variables :
    - The highlights issue.
    - change of color of the selenium in the bleach. (usually reddish) it is beautiful anyway.


    G.
     
  8. Guillaume Zuili

    Guillaume Zuili Subscriber

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    When I was assistant I asked why for the selenium.
    I got "it's like that"...
    Fine with me !
    :smile:
     
  9. Vaughn

    Vaughn Subscriber

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    The split toning I am familiar with is actually just selenium toning, not the combo of sepia and selenium toners. The shadows start to change color before the highlights...the old Portriga Rapid paper was one of the papers that worked well.

    I suppose the term dual-toning would fit better with what you are doing, but there might be some split toning going on as well.
     
  10. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    Selenium toner takes the silver in the print and converts it to silver selenide. Where there's lots of silver it is possible for the reaction to occur. Where there isn't any silver, it's difficult for the reaction to occur. Selenium is what's called a direct toner, meaning it does not require a bleach prior to toning.

    A sepia toner relies on silver to be bleached out of the picture, and re-halogenized into silver halide before a reaction with the sulfide toner can occur and turn the silver halide into silver sulfide. It isn't possible for the toner to react with silver directly, so the difference is that you turn it into silver halide before the chemical reaction can occur. Sepia is referred to as indirect toner, because it does require a bleach bath, and rehalogenizing bath prior to toning can happen.
     
  11. tkamiya

    tkamiya Member

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    If there isn't any silver, reaction with selenium toner does not happen - at all. But... highlight area does have some silver - just not as much as mid tones or shadows. Unless you are saying a lot of silver works as a catalyst (catalyst speeds up the process - without being consumed in the process), then I still think, little silver in highlight area will reach completion much sooner than shadow because there isn't as much time needed to finish the entire reaction.

    My understanding is, direct sulfide toner (brown toner) is also said to work on highlight first. So the direct/indirect difference probably isn't a factor here... I think.

    I really would like to understand this....
     
  12. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    Let's flip the coin. The absence of silver demotes the transformation of silver to silver selenide.

    Think of it like gasoline on water. If you set fire to it you will have lots of flames where there's plenty of gasoline, and very little, if any, where there's only a little. Why? Where there's a lot of fuel for the chemical reaction (rapid oxidation, or fire) to take place, it will happen quickly, but where there's little fuel, the reaction is a lot less violent.
     
  13. artonpaper

    artonpaper Subscriber

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    Could it be that the shadows aren't toning first? It may be that all that silver attracts more toner and it tones to a visible amount first. The highlights, comprised of smaller, more scattered silver particles, just aren't grabbing enough selenium to appear reddish but may be toning chemically. If one leaves the print in the toner long enough, it picks up enough selenium everywhere, and the print becomes visibly toned all over. But then this doesn't explain why some papers readily split while others, not so much, and sometimes not so red.
     
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  15. tkamiya

    tkamiya Member

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    Thomas,

    Using your analogy, the area with less fuel burns less violently but will run out of fuel first. (complete toning)
     
  16. tkamiya

    tkamiya Member

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    Artonpaper,

    That makes the most sense - it's toning everywhere but we can't see it. HOWEVER, if that was the case toning shadow with one toner and toning highlight with something else won't be possible.

    The only way I kind of figured it may work is that the first toner tones everywhere at the same pace. So the highlight tones first and fully to pickup the color of the first toner. But, silver rich area of shadow aren't completely toned so when I use the second toner, it picks up the color of the second toner which over-powers the first. Since the highlight is already completely toned, there is no more silver left to pickup the second toner.

    In other words, neither toners are toning shadow or highlight differently. It's the matter of which one comes first. Once highlight is completely toned with one toner, it will no longer react with anything else. Stopping this reaction before shadows are completely converted allows the second toner to pickup the process for the shadow.

    I wish our chemists (I know they are there!) chimes in.... so I can stop guessing....
     
  17. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    I didn't realize you were asking about split toning.

    As long as you understand, you can play devil's advocate all you want. But the relationship between direct and indirect toners is what makes it possible, like I stated above. Why not send Wolfgang Moersch an email? Or Tim Rudman. From personal experience they are both receptive and helpful.
    I will check in Rudman's toning book for clues tomorrow, if I can manage to remember.
     
  18. Doremus Scudder

    Doremus Scudder Member

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    In my experience, some papers show tonal change in the shadows first with selenium, but some tone much more evenly. I suspect the following is happening:

    Different papers, i.e., different emulsions, tone at different rates and by different amounts.

    Many (most) papers, and all VC papers have two or more emulsion components in them.

    It stands to reason, that these may tone at different rates and by different amounts.

    If your highlights are composed largely of silver grains of a particular size and configuration stemming from one emulsion component, but the shadows have silver grains of a different size and shape from another emulsion component, then split-toning (or dual-toning if you prefer) is readily understandable.

    Example: The older formulation of Seagull G papers (a graded paper) toned very evenly to a uniform eggplant/reddish color. Just a hint of this was really nice for a feeling of depth. The formulation changed when cadmium was banned, and the toning characteristics of the paper changed: different image tone, but still relatively even. Then, the formulation was changed again: Seagull G became GF. In this last formulation, the grade 2 paper split-toned rather heavily (and unpleasantly for my taste), but the grade 3 still toned evenly and to a different color than the grade 2. I'm not sure what the cause of all this is, but I'd put my money on emulsion formulation and different amounts of different size and shape of silver grains in the shadows as opposed to the highlighs. Now, Seagull G is gone, discontinued as so many other fine papers :sad: .

    I would imagine that the activity of selenium toner on a homogenous emulsion would be even, i.e., with all portions of the print toning at the same rate. The only thing that would make the shadows tone more slowly (and the highlight areas tone to completion first) would then be exhaustion of the toning solution in the more dense areas, similar to the effect of compensating developers. I don't know if this happens, but I suspect not. In that scenario, it would take longer for the shadows to tone than the highlights, which does not seem to be the case in my experience. This could be tested easily if one had a paper with just one emulsion component (or a completely bleached/rehalogenated print). I may try the test when I get back to the darkroom this summer.

    In addition, there are also the optical effects to be considered. In dense areas, the selenium color would predominate, since the entire area would be getting toned. In highlight areas, however, there is a lot of paper base showing through, with a color of its own, that is not getting covered by selenium toning. In very light areas, only a small percentage of the total area is actually being changed in tone; the paper base does not change color, so the overall tone change is less than in the darker areas. This obviously could contribute to the impression that the shadows change image tone before the highlights.

    And now, start combining these effects and what do you get? It is always more complicated than we think. :wink:

    Best,

    Doremus

    www.DoremusScudder.com
     
  19. michael_r

    michael_r Subscriber

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    It can help to think of Selenium as an intensifyer. The degree of toning is proportional to the amount of silver present, whether toned partially or to completion. This is why it works as a proportional intensifyer for negatives (ie contrast increase). Metallic silver converted or coated with Selenium blocks light more efficiently than untoned metallic silver. Hence the contrast increase in selenium toned negatives, and the enhanced d-max in papers.

    Regarding the differences in toning properties of papers in Selenium (degree, color), there are several factors. In addition to all the emulsion characteristics, my understanding is the degree to which the emulsion is hardened in manufacturing also contributes considerably.
     
  20. baachitraka

    baachitraka Subscriber

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    Wolfgang Moersch has showed some great photos with Holga 120N. I could not believe at first that they were shot with that camera.
     
  21. tkamiya

    tkamiya Member

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    Just so we are clear - I am not playing devil's advocate. I am trying to understand the WHY portion of these processes so I can use them to my advantage. I happen to have couple of prints right now that I think would be a good candidate for split toning. So far, the results are disappointing. It is one thing to take conventional wisdom and use it - but it is another to understand the reason behind those wisdom and really take an advantage of it.
     
  22. tkamiya

    tkamiya Member

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    Michael,

    Thank you. Does this mean that if I have an area where there is a lot of silver and another with very little, say 10 and 1, and tone it for X amount of time, if the former becomes 15, the latter becomes 1.5? - so that my assumption that less silver area will tone to completion first? Then what I need to research is the rate of change rather than the amount of change.....
     
  23. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    OK. Devil's advocate is a good technique for preventing groupthink, and that is a good thing. I didn't mean anything negative by that, quite the contrary. It's a commonly used technique in meeting discussions that someone is specifically assigned to play that role to break conventional thought patterns.

    Anyway, I suggest that for you to get good results with split toning, you don't need to understand the chemistry portion of it. Is it impossible to suggest to just accept that selenium tones 'bottom up' and sulfide toners tone 'top down'?

    You have two ways of using the two toners in combination:
    1. You bleach and use sulfide toner first, and after the following wash you use selenium. The selenium strongly affects the results of the sulfide toner.
    2. You use selenium toner first to protect the shadows, then bleach and use sulfide toner. This usually gives a much more subtle effect.

    You can also play around with bleach/sulfide, and then another round of bleach/sulfide. That yields interesting results as well.

    It matters what paper you use. Check out http://www.moersch-photochemie.de/content/knowhow/lang:en
    It has lots of examples of what you can do with various toners, bleaching, etc.

    Good luck! I hope you find a good way of working with these toners.

    - Thomas
     
  24. tkamiya

    tkamiya Member

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    I'm afraid I can't do that Dave.... (ref. 2001 Space Odyssey)

    One of my weakness is, I must find out why certain things work in a way it does and this is no exception. I'll report back when I find the reason why Selenium acts this way.
     
  25. artonpaper

    artonpaper Subscriber

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    The idea about intensification makes sense. Portriga, a graded paper, used to acquire very red shadows long before the highlights or middle tones. I've used poly toner, another direct toner, highly diluted, on Portriga, but it would tone the highlights first, leaving neutral darks if you caught it in time.

    I had a friend years back that would split tone Portriga in selenium, and then tone in an iron blue toner, which toned the lighter tones blue. So thinking about this suggests that there was still untoned silver in the areas that toned blue.

    And interestingly, I've had students take a print out of the bleach intended for sepia toning and stick it in the selenium. That resulted in instant redevelopment, with selenium tones.
     
  26. tkamiya

    tkamiya Member

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    I contacted Mr. Tim Rudman and he replied. He has generously given me his permission to share his response. Here are his key points:

    I took a liberty to combine two emails from him and removed some portion of it for clarity.

    I went ahead and ordered his book on the subject. I'll be studying it once it arrives.