Film gives off light when put into the stop bath?

Discussion in 'B&W: Film, Paper, Chemistry' started by Ian Leake, Dec 21, 2017.

  1. mitorn

    mitorn Member
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    Apparently the chemiluminescence of pyrogallol is well known. It happens when pyrogallol is oxidized, according to that paper (https://doi.org/10.1016/S0039-9140(97)00272-5) the emission of light is sensitive to the pH value and the maximum of the intensity depends on the oxidizing agent. For potassium permanganate the maxima is at 0.6-0.8 and zero above 5, whereas for hydrogen peroxide the maxima is 11.

    So you could try a different stop bath and hope for the best.

    and btw ....phosphorescence is the effect that something emits light long after it has been exposed to light (glow in the dark paint)
    fluorescence is the effect that something emits light of another colour while it is irradiated (black light paint under UV light)
    chemiluminiescence is the effect that something emits light during a chemical reaction…(glow sticks)
     
  2. eddie

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    Off topic, I know, but anyone have any suggestions for deliberately introducing this effect?
     
  3. AgX

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    A Kirlian apparatus.
    (A plain high-voltage apparatus, but be careful, we want you to stay here at Apug...)

    Otherwise you might try to pull the film fast through a slit in dry weather, or ripping off adhesive tape along the film length.


    Some modern films have special means to counter build up of static charge.
     
    Last edited: Dec 23, 2017
  4. Gerald C Koch

    Gerald C Koch Member

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    A bit of a nitpick. Phosphorus phosphoresces when exposed to air. Zinc sulfide luminesces after it is exposed to light.
     
  5. AgX

    AgX Member

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    "luminescence" as noun is the general term for all the effects summed up so far:

    phosphorescence
    fluorescence
    chemical-luminescence
    electroluminescence

    As verb one can use it in the latter two cases.
     
    Last edited: Dec 23, 2017
  6. Gerald C Koch

    Gerald C Koch Member

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  7. OP
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    Ian Leake

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    I’ve just spotted this in The Book of Pyro (Hutchings, 1992) page 52:
    “When negatives from pyro developer are placed in an acid stop bath you may notice a pale green glow on the negative surfaces. This is called chemoluminescence and is the release of visible light as the pyro is rapidly oxidised by the acid stop bath. This release of light will not harm the film.”​
     
  8. Sirius Glass

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    Great catch. Thank you.
     
  9. mitorn

    mitorn Member
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    I’m afraid you are wrong.

    You can call phosphorus phosphorescent in everyday language, but despite the similar name the blueish glowing, due to the oxidation of white phosphorus belongs to chemiluminescence. (https://en.wikipedia.org/wiki/Chemiluminescence#Gas-phase_reactions yes I know it is Wikipedia, still it is true).

    If we start nit picking, (pure) zinc sulphide should not show any luminescent behaviour, only if you activate/dope it, it will show luminescence… using Copper will produce slowly decaying greenish colour. Anyway since doped Zinc sulphide (depending on the dopant) shows phosphorescent, fluorescent and electroluminescent behaviour, it might be more appropriate to call it luminescent.
     
  10. Doremus Scudder

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    I find it interesting how the expertise on this forum has changed over time. Some years ago, someone posed exactly the same question. It was answered, authoritatively, in one or two posts, and no one went on about how terrible pyro developers are to do this or how stop bath can't be used with pyro developers because of the danger of fogging the film due to chemoluminescence. I'm very happy that the OP found the relevant passage in Gordon Hutching's book and posted it here to dispel and misconceptions.

    I've been using PMK for 30+ years and see this phenomenon occasionally, but not the majority of times. I think the longer the developer stands and oxidizes before development takes place has an impact. I've seen no effect on the developed film from this phenomenon. I think it's kind of cool and smile to myself in the dark when it happens.

    Best,

    Doremus
     
  11. Jarin Blaschke

    Jarin Blaschke Member
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    Indeed, maybe the forum is more chatty these days. Advanced analog photography techniques are probably reaching the "arcane" category soon, and "authority" harder to find. But at least we can still find each other.

    I figured that as a pyro user, maybe I had some room to complain in jest - compared to HC-110 or Rodinal, it kind of is a pain in the a--. But, this matters little to the small group within the small group that didn't just buy a 5D and call it done. And really, the pyro thing is only a pain on top of the sheet film thing.

    I'm relatively new to pyro and sheet film, and see the luminescence most times it goes in the stop bath. It's pretty, and kind of gives me comfort, like I know the stop bath is working.

    J
     
  12. Arctic amateur

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  13. trendland

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    The only comparable situation I remember with ilumination from liquits is a night flight departure from an a/c carrier.
    You can determine sometimes a glow caused from the ship's propeller.
    This phenomen is well known. It can also help a bit to notice the carrier before landing in extreme dark nights - because the ilumination is much often seen long time before the landing lights are visible.
    Caused from big ships like carriers it can have a lenght much more than an a mile.
    with regards

    PS : The example from above is bioluminescence comming from little creatures (bigger than bugs) in the water caused from movings (ship propeller )
    What you have seen is chemicalluminescence - I guess not so many bugs and bigger creatures would live in you developing tank.
    Otherwise you should have to clean your tank a bit ??? :D:laugh::D:happy::laugh::cool:....
     
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  15. Old-N-Feeble

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    My face glows bright red when eating very spicy foods. Is this called capsaicin-luminescence? Is there any chance this phenomenon could fog my film if I process film too soon after eating spicy foods? Maybe if I use a taco-style film processor it'll negate this problem?
     
  16. Sirius Glass

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    Is 5D some new film?
     
  17. OP
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    Ian Leake

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    Actually I was thinking the opposite: how nice it is that there's somewhere I can post a fairly arcane question and get good natured and meaningful help. My question was answered the same day (post 12) – albeit with some festive cheer in between. (I did do a search but obviously missed the thread you're referring to.)

    Thanks for this information. I mix my developer only once everything else is ready; then pour it into the tray, turn out the lights, and reach for my film.

    Despite what Hutchings wrote, I'm not wholly convinced that this chemoluminescence doesn't affect the negative. I experienced the phenomenon during a BTZS film test: the negatives had measurably higher FB+F than a repeat test I did later the same day with a water stop bath. Of course it's entirely possible that this may have been due to another factor.
     
  18. Jarin Blaschke

    Jarin Blaschke Member
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    Did you find that the fog was uniform, or greater at denser parts of the negative? I'm new to 8x10, and am seeing some blooming in dense highlights when bordered by thin areas. My lens looks quite clean and am trying to track down its cause.

    Do you use a pre-soak, by the way? This is a process that I use, that adds time that the developer is oxidizing.

    j
     
  19. OP
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    Ian Leake

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    For a properly developed negative on properly stored film, FB+F is constant across the negative. It sounds like you're describing some sort of edge effect. I guess you could exclude film, camera, lens, lighting, etc. by making two identical negatives and developing one in pyro and the other in a conventional developer. But sorry, I'm not enough of a pyro expert to diagnose this.

    Yes, approximately 2 minutes.
     
  20. DREW WILEY

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    I saw it a long time ago in sheet film trays. I've used a variety of pyro formulas over the years, mostly PMK. But I also routinely mix the stop bath way weaker than most people do - around 1/4 percent. It doesn't require much to get the necessary pH change. I use it just once then toss it out. Maybe the habit of re-using it explains the traditional 2 percent formula of acetic acid.
     
  21. DREW WILEY

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  22. nworth

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    Some posters seem to confuse the triboluminescence that happens when pulling tape off the film with the possible chemiluminescence described here. Two observers have mentioned that it happens with pyro developers, so it would be interesting to know if you are using a pyro developer. You also did not mention what kind of stop bath you use. I've found that with developing times greater than 5 minutes, using a couple of fresh water rinses works as well as a stop bath. This might cure the problem. A different stop bath also might (might) work. The real question is whether it makes any difference. You could process a blank sheet using water rinses and another using your flashy stop bath and see if you see any difference in density between the two.
     
  23. Sirius Glass

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    Please correct me if I am wrong: I thought that one did not use or need stop bath with Pyro.
     
  24. Doremus Scudder

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    Stop bath works just the same with pyro developers as with any other, since they are active only in an alkaline environment. I like keeping my film developing regime downstream of the developer acidic, just to ensure that the developer doesn't get reactivated. In the past, I've experienced some fogging when using an alkaline fix and switching on the white light too soon during fixation (even at "halfway" through). An acid or neutral fix won't allow the carried-over developer to be reactivated.

    The only developer I know of that works in an acidic environment is amidol, and I think a stop bath is commonly used with this print developer as well.

    Best,

    Doremus
     
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