pH-Caused Temporary Reticulation?

Discussion in 'Black and White' started by trooper, Mar 24, 2004.

  1. Recent discussions in here regarding reticulation touched on the pH
    shock effects. I've been noticing a temporary reticulation that
    appears as a "frosty" sort of finish when I first hang my washed films
    up. I notice it most on medium format Tri-X but also on Ilford films,
    too. When fully dried, it seems to not be apparent and the film seems
    normal (perhaps a very vague retention of pattern under a 45X viewer).
    In a recent "Duh" moment, I realized that I started seeing this about
    the time I was switching to an alkaline fixer (TF-4). Is there some
    sort of pH related issue at work here? I'm skipping the acetic acid
    and using 3 flushes with tempered water following my developer (FG7
    w/o ss, Exactol Lux and W2D2+). I'm quite certain my tempering
    methods rule out temperature related issues.
     
  2. I use TF-4 and tempered water, and have never seen this with Ilford FP4+. Haven't tried the new process Kodak films yet. I use 3-5 changes of water just as you do. If anything, an all akaline processing chain should minimize this sort of thing. Were you using a hardening fixer in the past? I assume you process at 68-70F. If it's higher, a case can be made for using hardener.
     
  3. I process at 70° and was in a habit of using Kodafix for many years. I assumed that the alkaline chain I am currently on would be less stressful to the emulsion than the acetic acid stop and Kodafix sequence before. My final results are fine but I was mainly curious about what was really going on to produce this very distinct effect that I described. I've been pleased, in general with the chemistry I'm currently using but sometimes feel tempted to settle back into the comfort zone of D76 1:1 and old stand-by (for me) stop and fix routines.
     
  4. Alkalis cause the emulsion to swell and acids casue it to shrink so a change from alkaline to acid can casue reticulation. Having said that, I use Rodinal (which uses pot. hydroxide - strongly alkaline) and and acid stop (Kodak - diluted 1+15) and have never had a problem with reticulation.
     
  5. I, too, have seen the "frosted" look on Tri-X and Ilford B&W films when hanging them in the drier. When full dry, the films are clear. I have always thought that this was caused by water adsorbed in the emulsion. I am using various developers (depending on films, the effects wanted, etc.) and always use an acid stop bath with hardening fixer. I cannot see any reticulation on dry 35mm, 120mm or 4 X 5 films. I have seen reticulation on 4 X 5 films when they were accidentally washed in hot water, but that is the only time.
     
  6. I assume the "frost" is in the emulsion side.
    You maybe be seeing some emulsion swelling that may look like "fish scales" or "lambs wool" when wet
    After it dries it'll be perfectly flat.
     
  7. I've seen the "frost" effect you describe on every roll of TMY-120 I've developed; in all cases, the film cleared up completely when dry. What I think you're seeing is a texture applied to the gelatin in the coating process -- Tri-X in 120 size, at least, is (or used to be) specified by Kodak as being retouchable on the emulsion side, which would imply that the gelatin has a tiny bit of "tooth" to allow it to accept pencil or other color. When the gelatin swells while wet, that texture may scatter light more -- though I'm surprised you've only seen it with alkaline fixer, since acid stop and fixer swell the emulsion more than an all-alkaline process. Even plain water, however, can swell emulsion after a half hour of immersion time comparable to the full develop-stop-fix-wash process.

    As long as the emulsion returns to normal on complete drying, I wouldn't worry about it -- on my TMY-120 films, I use it (along with a change in the curl, from emulsion in to emulsion out and then back to emulsion in -- caused, I think, because the thinner anti-curl coating on the back dries faster than the emulsion) to tell me when the film is close to being dry.
     
  8. This evening, I processed a variety of films and discovered that in one tank, a roll of FP4+ 35mm showed no behavior of this but the FP4+ 120 roll that was in the same tank did. On reflection, I realize that I've shot almost no 35mm B&W in the last year and almost universally medium format. I've also changed where I'm initially hanging film out of the tank in the last year and I think that the new angle of a wall mounted, short flourescent is a big reason I began noticing this frosted/texture effect. I think the response to my initial question on this that referred to a possible re-touch surface on 120 may be the most likely answer.
     

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