Results 1 to 7 of 7

Thread: Question about Chemical Shelf Life

  1. #1

    Join Date
    Mar 2012
    Posts
    28

    Question about Chemical Shelf Life

    So I'm currently running Ilford chemicals for both film and paper (although I'm using Kodak's Photoflo).

    At the moment, I'm only mixing what I need. For instance, if I'm doing some printing. I mix up a tray's worth of developer, stop and fix. And squeeze as much air out of my bottles as possible.

    Once I'm done printing, I throw out the chemicals in those trays. I've always been under the impression that the undiluted, straight-from-the-factory chemicals have a longer shelf life than if I mixed up a big batch of chemicals and stored those. My method also cuts down on the number of random bottles I have laying around.

    Am I right in assuming this? The only downside I can see to the way I do it is that I have to mix chemicals every time I want to develop or print.

    I also use my chemicals as "one shot" because I just don't go through them fast enough for it to matter.

  2. #2
    8x10, 5x7, 4x5, et al Leigh's Avatar
    Join Date
    Dec 2010
    Location
    Maryland, USA
    Posts
    5,059

    Re: Question about Chemical Shelf Life

    I've been doing the same for over 50 years with no problems.

    The shelf life of the concentrates will vary with the particular product.
    Developers are the most volatile, subject to deterioration. But even those vary over a wide range.
    Rodinal will keep in concentrate form, even in a partially used bottle, for decades.

    Other chemicals like fixer have very long shelf lives. I keep working-strength stop bath until it changes color.

    I assume you're talking about liquid concentrates. You can't mix partial batches of powdered chemicals.

    - Leigh
    If you believe you can, or you believe you can't... you're right.

  3. #3

    Join Date
    Dec 2006
    Posts
    951

    Re: Question about Chemical Shelf Life

    Quote Originally Posted by ckpj99 View Post
    So I'm currently running Ilford chemicals for both film and paper (although I'm using Kodak's Photoflo).

    At the moment, I'm only mixing what I need. For instance, if I'm doing some printing. I mix up a tray's worth of developer, stop and fix. And squeeze as much air out of my bottles as possible.

    Once I'm done printing, I throw out the chemicals in those trays. I've always been under the impression that the undiluted, straight-from-the-factory chemicals have a longer shelf life than if I mixed up a big batch of chemicals and stored those. My method also cuts down on the number of random bottles I have laying around.

    Am I right in assuming this? The only downside I can see to the way I do it is that I have to mix chemicals every time I want to develop or print.

    I also use my chemicals as "one shot" because I just don't go through them fast enough for it to matter.
    There is no need to throw out stop and fixer after each printing session. That wastes materials and money. Almost all Stop have an indicator dye that will change color when it is exhausted. You can by Hypo-test to test your fixer as well, or you can count sheets as recommended by the manufacturer. I do endorse your policy of employing a fresh dilution of print developer for every darkroom session though.

  4. #4

    Join Date
    Mar 2012
    Posts
    28

    Re: Question about Chemical Shelf Life

    I am talking about liquid concentrates. From you folks have said, I think I might mix up some fix and stop in liter jugs. I'm going to stick to my developer plan.

    What about Photoflo [hypoclear]? Is it stable when mixed up? It seems like something that doesn't need to be reused since it's so cheap.

  5. #5
    8x10, 5x7, 4x5, et al Leigh's Avatar
    Join Date
    Dec 2010
    Location
    Maryland, USA
    Posts
    5,059

    Re: Question about Chemical Shelf Life

    That's what I do. Discard the developer after use, but save the stop bath and fixer.

    Photoflo is not hypo clearing agent. Two very different things.

    Hypo clearing agent (e.g. PermaWash) changes residual fixer to a water-soluble compound so it washes out easily.

    PhotoFlo is just soap, used to reduce the surface tension of the water so it runs off rather than beading.
    It should be the absolute last step before you hang the film to dry. Don't remove it before drying.
    It's mixed at a ratio of 1:200 or 1:2000, depending on whether you buy PhotoFlo 200 or PhotoFlo 2000.
    I don't bother to save it; just mix, use, and discard. It's super cheap.

    - Leigh
    If you believe you can, or you believe you can't... you're right.

  6. #6
    tgtaylor's Avatar
    Join Date
    May 2006
    Location
    San Francisco Bay Area
    Posts
    3,853

    Re: Question about Chemical Shelf Life

    I store stock solutions of Kodak Dektol and Xtol in tanks with floating lids. The stock solution will keep for several months in those tanks and I've actually developed film with Xtol that had been so stored for 6 months without a problem. I use the working solutions one shot and toss.

    I use PF TF5 fixer which I mix for each run and use it one shot if rotary processing, to completion if developing by hand inversion, and one session and then toss if developing paper. Keep track of the number of prints processed when printing so that you will know when you're approaching the limit on the developer and fix.

    I use a citric acid stop and mix enough to last 2 or 3 sessions and store in a brown plastic bottle between sessions. Same thing with the Photoflo which I store in brown plastic bottles marked for paper or film.

    For hypo Clear I mix sodium sulfite for each session and toss after use.

    Thomas

  7. #7

    Join Date
    Sep 1998
    Location
    Oregon and Austria
    Posts
    1,918

    Re: Question about Chemical Shelf Life

    Tossing print developer after one session is standard practice for many. I think this is because a full day of printing is usually close to the capacity of a tray of developer. (That, however, is for "standard" type print developers. Some developers, like Ansco 130 have longer working lifespans and last for weeks before exhaustion.)

    That said, I'll often use a tray of developer the next day if there were not too many prints run through it before. I cover the solution in the tray with Saran Wrap or pour it carefully back into a bottle; Oxidation is the real enemy of developers; some oxidize faster than others. As long as the capacity has not been reached and the developer has been protected from oxidation, it will be fine the next day. If it is not discolored, it has not oxidized. For printing, it is a good idea to know the capacity, in throughput, of your developer to use as a guide whether to save it or not for the next day. Of course, if you're not going to print for another week, then toss it.

    Film developers are usually used one shot. There are some that still use replenished developers in tanks, but most of us don't develop film every day and one-shot works best for consistency.

    Stock solutions of developer have different shelf-lives, as mentioned above. I have kept a full jug of Ilford Bromophen stock for six months or more and it worked just fine; no discoloration at all from oxidation. Many film developer stock solutions last months or even years (Rodinal, PMK, etc.). Read the manufacturers' information sheets to determine the shelf life of the developers you use.

    Stop bath working dilutions you can use till the indicator changes. I rarely even pour it back into the bottle when I'm actively printing every day. I just leave the full tray sitting there in the sink. For film I just mix a liter and use it till the indicator just starts to change. Be careful if you use a citric-acid stop, since they have a tendency to grow slime with protracted storage (I use citric-acid stops at half-strength, one shot); acetic-acid stops do not degrade and can be kept till the pH is no longer adequate to stop development quickly (i.e., when the indicator changes color).

    Fixer can also be reused up to the point of exhaustion or loss of activity due to age; Ilford gives a seven-day working life for its Rapid Fix and Hypam in open trays. I keep track of the capacity, use two bath fixing for fiber-base paper and just leave the tray out like the stop. I toss the fix when capacity is reached or the seven days are up. For film, I try to collect enough to develop so that I can use my fixer "one-session." If I were developing roll films, I might mix a liter or half-liter and use it for a few weeks, doing clip tests before each tank to determine fixing time. Again, toss the fix when capacity (i.e., 2x clearing time in fresh fix) or the lifespan has been reached (Ilford says one month in a half full tightly capped bottle or 2 months in a full tightly-capped bottle for its Rapid Fix and Hypam).

    Hypo Clearing Agent and similar products are solutions of sodium sulfite plus some other chemicals. It goes bad in 24 hours (oxidation). Use it one-shot or one-session and keep track of capacity.

    PhotoFlo will also grow slime with protracted storage. Most use it one-shot/one-session. If you have hard water, like I do, mix your PhotoFlo with distilled water for the final rinse and toss it after each session so that the hard-water chemicals don't build up in it.

    Generally, it is a good idea to make a list of the capacity, in throughput, and working life of all the chemicals you use. This will allow you to reuse when practical and know when to discard when necessary and save you lots of headaches in the future (as well as a few pennies).

    Best,

    Doremus

Similar Threads

  1. Pyrocat HD Shelf Life
    By blevblev in forum Darkroom: Film, Processing & Printing
    Replies: 19
    Last Post: 29-Jan-2012, 10:20
  2. Shelf life of PMK
    By Bill Kumpf in forum Darkroom: Film, Processing & Printing
    Replies: 6
    Last Post: 18-Apr-2011, 11:03
  3. PMK Pyro shelf life
    By Tom Keenan in forum Darkroom: Film, Processing & Printing
    Replies: 4
    Last Post: 18-Apr-2009, 06:35
  4. Ektalure Shelf Life
    By Alex Hawley in forum Darkroom: Film, Processing & Printing
    Replies: 0
    Last Post: 19-May-2008, 12:19
  5. Shelf life PMK
    By Shen45 in forum Darkroom: Film, Processing & Printing
    Replies: 2
    Last Post: 29-Oct-2007, 18:19

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •