Fixing with lights on ?

Discussion in 'Black and White' started by marc_tz, May 27, 2009.

  1. Hi all
    I am wondering if someone has ever tried to fix negatives with the lights _on_ (I mean: switch the lights on immediately after the acidic stop bath) ?
    I know that some of those using BTZS tubes (sheet film) change the chemicals by opening the end cap for a few seconds in weak light, but what about conducting the whole fixing step under light ?
    Please note that I am referring here to common films of moderate sensitivity and to an acidic stop bath (2% acetic acid, pH about 4.5) that should strongly arrest the activity of the developer soaked by the emulsion. But can the higher pH of a "neutral" fixer let the developer acting again ? Has somebody conducted some fiable, sensitometric tests ?
    (Ok, I could see for myself... but I'm currently now 500 km far from my lab !)
    Thanks for any comment or advice,
    Marc
     
  2. Does stop bath take out (neutralize) 100% of the developer?
    Then what happens if the film is immediately exposed to light after stop bath is dumped and then fixed?
     
  3. I have tried this and baked the negatives. I fix paper prints with the lights on all the time; put the print in the fix for a moment, go over and turn on the lights; no problem. I suspect that negatives are too fast to react.
    It's not entirely impossible; Polaroid found a way to get their black and white pictures working in the daylight; yet, I think that for negatives, it will be best to keep them in the dark. Or, ortho films.
     
  4. Bad idea. Film will fog until it's fixed. I wouldn't trust stop bath to prevent fogging of unfixed negatives. Paper is much, much slower so there's more margin for error. But I don't turn on the lights until the prints on RC paper have fixed for at least 30 seconds. And I wouldn't risk film or fiber prints until they've been completely fixed. I'm not that curious or impatient.
    I'm curious about why you'd even want to do this? But if it's just idle curiosity, I suppose you could test it for yourself. You might need a densitometer to accurately evaluate the differences.
     
  5. When I took large format this past semester, our teacher told us that we could turn on the lights after the negatives had been fixed for one minute. I'd only developed 35mm and 120 in stainless steel tanks before, so I'd never heard of doing this. However, since a few of us often had to develop our 4x5 film together, other kids would often turn on the lights after one minute of fixing and the negatives were never damaged.
     
  6. OK, being that the techie side is well covered< I'll just type the first thing that came to my mind. Bad idea. and Why?
     
  7. When you think about what fixer actually does, you'll realize why turning the lights on before fixing is a bad idea. The fixing step removes the undeveloped and unexposed yet still light sensitive silver crystals in the film. It's essentially unexposed film. Bring it into the light before fixing and now those crystals will convert to silver and the result will be fog.
    The stop bath will stop developement of previously exposed parts of the film but has no effect on the light sensitivity of those areas not yet exposed.
     
  8. At first it was just a question of curiosity (there are a lot of procedures that are just taken for granted like the universal requirement of washing films for half an hour under Niagara falls despite the fact that a few rinses are OK)...
    Nevertheless it could be helpful to be able to remove the films from the BTZS tubes waiting on the stop bath tray and putting them with the lights on all toghether in a tray or a Combiplan basket for the fixing step.
    But well.. I'll try this by myself (i have a densitometer) and let you know soon - which should translate as "in a couple of week"..
    Thank you all,
    Marc
     
  9. Karl,
    When you test a film in the fix for clearing time, it's done on white light, the film is full of unexposed yet still sensitive crystals and it never develop fog. What is of concern is the remaining dev in the emulsion that could remain active at the fixer pH. But as said, I will simply give a careful and quantitative (densitometry) try on several unexposed/exposed film.
     
  10. I have opened the tank after the alotted time has passed a few times only to find the film has not cleared and then proceeded to continue fixiing with the light on till the film has fully cleared. The above comments may explain why these films are usually a bit badly developed. And it mainly happened on the 2 roll sof Tri-X I had ago with, both of which took an absolute age to fix (10mins plus). I thought the poor results were down to the film but maybe it is my fault?
     
  11. I routinely open the developing tank after ~1min. I want to:
    • Make sure I fix for 2x the clearing time (or more if the film was already clear when I opened)
    • Spot the time when clearing time increases, signaling it's time to change the fixer
    I have not noted adverse effects, but maybe that means I'm not sophisticated enough?
     
  12. I routinely open the developing tank after ~1min.​
    Me too. I like watching the film clear!
     
  13. I do the same thing that Bernard wrote, and you know what? It's not a problem. I have even opened the tank after the stop and before the fix, and it was still fine. Developing agents cannot work in an acidic environment, so there won't be any more fog. Now, mind you that I'm not recommending this as good practice. All I'm saying is that I've seen no practical difference. Does this observation hold true if the fixer is alkaline and no acid stop is used? Maybe, or maybe not. Caution dictates that it might not, so I wouldn't try it with anything I'd care to keep.
    To Nigel... It's fairly common knowledge that Kodak's TMax films are particularly hard on fixers, and that they take a considerably longer time to fix out than some other films. But Tri-X and Plus-X also take a little longer to fix out, and a a bit harder on fixers, than films of similar speed and characteristics from other manufacturers. So what you're seeing isn't terribly uncommon, especially if you're using a standard sodium thiosulfate based fixer that's seen a few rolls of film already.
     
  14. I often frighten people in my darkroom by turning on the lights while my just developed 8x10 sheet film is lying in the stop bath tray. Provided the developer is fully neutralised the film will not show fog after subsequent fixing. Modern developing out materials do not precipitate usable quantities of silver on light exposure. They do precipitate silver atoms but these are sufficient only for a latent image that must then be developed to be seen.
     
  15. Maris, thanks for that useful information. That's exactly the way I was thinking the whole thing. Except for the remaining dev soaked by the emulsion, I see no reason why the film should fog. I will conduct some careful, quantitative tests on the matter and post the results asap.
     
  16. Well, I once dumped a daylight tank when pouring out the developer. The negs came out a little dense. I think that had I left it out for a few more seconds, the film would have gone completely black.
     
  17. The only thing I would add is if you use a water rinse as a stop and also use an alkaline fix, leave the lid on till the fix has worked the required time accoring to specs, then check it.
    Ever heard of monobath developers? These work with fixer and developer going at the same time, the fixer dilute enough the developer gets done before the fix does. With an alkali fix and film dropped in with developer still in the emulsion this is pretty much what you have going on.
     
  18. The only thing I would add is if you use a water rinse as a stop and also use an alkaline fix, leave the lid on till the fix has worked the required time accoring to specs, then check it.
    Ever heard of monobath developers? These work with fixer and developer going at the same time, the fixer dilute enough the developer gets done before the fix does. With an alkali fix and film dropped in with developer still in the emulsion this is pretty much what you have going on.
     
  19. Argh! No way to delete a multple post?
     

Share This Page

1111