Permawash: how long does it last?

Discussion in 'B&W: Film, Paper, Chemistry' started by ymc226, Oct 31, 2011.

  1. ymc226

    ymc226 Member

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    I'm not a chemist and follow the recommendations regarding life of stock solutions of Xtol and Dektol that I mix up.

    I bought a gallon of Permawash a while ago and have been slowly using it up in my FB paper and film processing. I haven't divided it into smaller containers where I can exclude air more easily but have kept it in the gallon jug it came in. Does Permawash last forever or even close as I assume it is still active (time will tell though)
     
  2. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    Permawash and all other 'hypo clearing agents' will go off with exposure to air. The S. Sulfite oxidizes to S. Sulfate.

    Use a residual hypo test on washed prints to make sure the stuff is still working. I think one should always use a residual hypo test when using a hypo clearing agent - otherwise one finds out much too late that there is still hypo in the prints.
     
  3. Doremus Scudder

    Doremus Scudder Member

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    A good reason to mix your own wash-aid from scratch just before use and discard it immediately afterward. One can simply use sodium sulfite, but a bit of metabisulfite added helps to keep the emulsion from softening too much. Easier and cheaper than buying powders or liquids.

    Here is my formula:

    Hypo-Clearing Agent (One Shot)
    Water (125º F) 1 liter
    Sodium Sulfite 20 g
    Sodium bisulfite (or metabisulfite) 0.2 g
    Water to make 1 liter

    Since the proportions are not too critical, I skip the weighing above and mix with measuring spoons:

    Sodium Sulfite 1 Tbsp (approx. 22.8g)
    Water 1 liter
    A pinch of Sodium Bisulfite or Metabisulfite will lower pH a bit but is not really necessary.

    This is easy to mix on the spot, ok if the water is not too hard (if your water is hard, you may need Calgon, aka EDTA. More sophisticated formulas contain this and sodium citrate, but if you have soft water or mix with distilled or demin, then you don't need them). Essentially the same as the formula above.

    Hope this helps,

    Doremus Scudder
    www.DoremusScudder.com
     
  4. Gerald C Koch

    Gerald C Koch Member

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    It is important to be careful about making generalizations about the various washing aids. While the end result, that is the reduction of thiosulfate ion in film and papers is the same, their mode of action is not. If you look at the MSDS for Permawash you will find that it does not contain sodium sulfite.
    .
     
  5. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    From the MSDS:
    AMMONIUM SULFITE Less than 20%
    SODIUM 2-ETHYLHEXYL SULFATE ETHYLHEXYL SULFATE Less than 5%

    Ammonium Sulfite rather than Sodium Sulfite - and this has a different 'mode of action'?. It doesn't oxidize? Sorry, I don't understand your statement, could you elaborate?

    The 2-ETHYLHEXYL SULFATE is a surfactant / wetting agent.
     
  6. Gerald C Koch

    Gerald C Koch Member

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    There are two products called Permawash and in my haste got the MSDS for the wrong product. Heico Permawash does contain ammonium sulfite BUT at the recommended dilution of 1+43 the sulfite concentration is too low to have the same action as the sodium sulfite in HCA. The action of Permawash is due to the surfactant and other chemicals (trade secrets) where the action of HCA is due to the sulfite.
     
    Last edited by a moderator: Nov 2, 2011
  7. Worker 11811

    Worker 11811 Member

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    Okay, this brings up another question for me.

    The way I understand, there are two main types of wash agent for film and paper. One type simply makes the fixer more soluble in water so that it can be washed out. The other actually binds to or breaks down the fixer into less harmful substances that are more easily washed away.

    I thought products like Kodak's Hypo Clearing Agent are the first type which make fixer more soluble. That is what I have used most often. However, I recently started using Heico Perma-Wash. Is this the "dissolving" kind or the "breaking down" kind?

    Are there any implications of using one type of washing agent over the other that I should be aware of?

    As to the original question, I have been mixing Heico Perma-Wash on a per-batch basis, straight from the bottle, using 23 ml of concentrate to a liter of water. Keeping the bottle tightly capped and stored in the cabinet under my bench, I don't expect there to be much problem with degradation due to age/time/oxygen. At the rate I'm using the stuff, I expect a quart bottle to last a good, long time.
     
  8. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    My experience with Permawash is that it doesn't really work very well even when it is fresh. The idea that surfactants will remove hypo seems to be based more on magical thinking than on any research reported by Haist or Mees. And I remember calculating, as you have, that the Sulfite concentration is much too low. To add insult the MSDS says "Am. Sulfite less than 20%" [italics mine], so what ever it is, it isn't 20% as one might think at first blush - it could just as well be half the amount. I suppose one could evaporate the water and see what's left behind, specific gravity should give the the sulfite to surfactant ratio. I don't think there are any magic trade secret chemicals, but I could be wrong.

    The Kodak HCA formula works very well and the stuff is cheap to make up. My conclusion, after finding the Permawash was not working was to not bother with the stuff any further.
     
  9. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    The two are 'hypo clearing agent' (HCA) and 'hypo eliminator'.

    HCA is based on Sulfite that has been buffered to the pH of gelatine's iso-electric point. The formula for Kodak's version is, as near as anyone can tell:

    5 gm Calgon (only needed if you get white calcium precipitate because of hard water)
    100 gm S. Sulfite
    20 gm S. Bisulfite
    5 gm S. Citrate (optional, off hand can't remember the purpose of it - pH buffer or preservative?)
    Water to make 1l
    Dilute 1:4 for use

    Hypo eliminator is made from Ammonia and Hydrogen Peroxide and has a shelf life measured in minutes. It will remove the last traces of hypo from prints than have been treated with HCA and well washed. Hypo eliminator is no longer recommended - it seems a small residual of sulfur complexes lengthens print life rather than shortens it.

    Permawash is a clearing agent.

    As Gerald has pointed out the working solution of Permawash has less than 5gm of sulfite per liter of working wash, Kodak's formula has 20gm of sulfite per liter.

    If you are using Permawash at a very low rate then the chances are very good the sulfite in it will have oxidized before you have finished the bottle.
     
    Last edited by a moderator: Nov 2, 2011
  10. john_s

    john_s Subscriber

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    Nicholas, I think i remember reading that the product called Calgon is actually not the same in all parts of the world. I don't remember where I read it. Richard Knoppow from time to time posted on the pure-silver list a formula like the one you have given but with EDTA instead of Calgon. From one of his posts:
    <start quote>
    Sodium Sulfite, dessicated 100 grams
    Sodium Bisulfite 20 grams
    EDTA tetra-sodium salt 1 gram
    Sodium Citrate 1 gram
    Water to make 1 liter
    <end quote>

    And from Ryuji Suzuki's now-defunct web site:
    <start quote>
    Kodak Hypo Clearing Agent contains EDTA and sodium citrate to reduce the calcium scum. With hard water, sulfite in the wash aid forms insoluble calcium scum unless EDTA is added. These are also useful in preventing precipitation of aluminium hardener that may be carried over from the fixer (if acid hardening fixer is used).
    <end quote>

    I just use the sulphite plus a little metabisulphite (=bisulphite). Very cheap if you mix from bulk chemicals, and toss it at the end of the day.
     
  11. Doremus Scudder

    Doremus Scudder Member

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    Thanks Nicholas for all the info about Permawash.

    I've also found that Permawash is less-than-adequate. Although I have not tested it, I cannot help but believe that their recommended treatment and washing times are also suspect. Kodak and their scientists have done trustworthy research. I'll rely on it.

    Best,

    Doremus

    www.DoremusScudder.com
     
  12. Gerald C Koch

    Gerald C Koch Member

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    I remember reading an article many years ago that washing aids such as Permewash and Orbit Bath work by using a detergent to speed the removal of thiosulfate ion from emulsions and in the case of papers also from the paper backing. HCA works by replacing the thiosulfate ions with sulfite ions. The sulfite ion is easier to wash out than the thiosulfate ion particually from papers.

    Yes, oxygen in the air will slowly oxidize sulfite ion to sulfate ion. But sulfate ion is also effective as a washing aid along with such salts as sodium citrate and sodium chloride. Sodium sulfite is used because it is more effective thasn the others.
     
  13. Mark Crabtree

    Mark Crabtree Member

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    It is nice to finally learn a bit about Permawash. In the old days, many people considered it to be the premium product, but I never heard any factual information about it. I never knew anybody that used or believed the recommended times though.

    To the folks who found Permawash not to work well - I assume you are talking about residual hypo tests in comparison with HCA (or similar) for the same treatment and wash times??
     
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  15. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    Yes
     
  16. dnjl

    dnjl Member

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    How long does the sodium sulfite last in powder form? I bought a 19L pack of Kodak HCA because I couldn't get anything smaller. I mix half a teaspoon just prior to using. Does the powder oxidize too, or is that only if you mix it with water?
     
  17. Gerald C Koch

    Gerald C Koch Member

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    Sodium sulftie solid is reasonable stable. However, if you expect to take months to use it up then you may wish to transfer it to a Mason jar or some other glass container.
     
  18. winger

    winger Subscriber

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    Could you elaborate on which tests? The one I used (and I don't have it anymore, so I can't look at which it was) said that if you used something like Permawash, then the test wouldn't be accurate because it will react with something left by it as well as with residual fixer.
     
  19. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    HT-2 (silver nitrate & acetic acid) is the standard test.

    If Permawash caused this [or one of the dripping tests] to show a false positive then I think the news would be shouted to the rafters by Heico. People who test and are satisfied with Permawash usually have a protocol that includes 1 hr in a Versalab print washer or some such - proof only that Permawash doesn't prevent one from washing prints normally.

    Advice to not trust test results when using Permawash sounds like very dodgy advice to me.
     
  20. Leigh B

    Leigh B Member

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    Can anyone recommend a test (chemistry and protocol) that will give an accurate measure of residual hypo under all processing scenarios?

    A test that works in some situations but not in others is meaningless for comparing methods.

    - Leigh
     
  21. Ryuji

    Ryuji Member

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    Detergents do not have significant role in accelerating washing process.

    Presence of detergents should not affect the reading of silver nitrate test for residual thiosulfate. If it comes out yellow or brown, washing is inadequate.

    Don't worry about "softening of the emulsion" stuff copied and pasted from old books. If the emulsion is not too soft in the print developer and rinse or stop bath, it will be fine in plain sulfite bath used as washing aid. Use a 35mm film canister full of it in a liter of water and it should be close enough.
     
  22. RalphLambrecht

    RalphLambrecht Subscriber

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    fully agree
     
  23. Tom1956

    Tom1956 Inactive

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    Seeing the thread today about Selenium toner led me to google up related questions. And this old thread popped up. Referring to one of the posts as quoted leads me to ask a question. The poster claims he just spoons out a small amount of Kodak HCA powder and mixes it as needed. Now we all know you can't do that with powdered developer for instance because a relable equality of distribution of the various components can never be known. Is it not the same problem with HCA? Or was the poster ignorant and didn't know you can't do this? Is the HCA powder out of the package a homogenous compound allowing small portions to be spooned out?
     
  24. MattKing

    MattKing Subscriber

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    Kodak HCA consists of just two components: Sodium Sulfite and Sodium Metabisulfite.

    As I understand it, the Sodium Sulfite does the work, and Sodium Metabisulfite helps preserve the solution once it is mixed.

    Most likely, the Sodium Sulfite constitutes the majority.

    If one is intending to use the result one-shot, the presence of preservative is rather unimportant.

    So unlike developer, where the relative ratios of the two components are important, using slightly un-homogenous HCA is unlikekly to cause problems.

    You do need to use somewhat more than the minimum though, and that combined with the one-shot use means that it isn't the most economical way to use it.
     
  25. Tom1956

    Tom1956 Inactive

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    Matt, thank you. While I have come to accept you as a credible poster, I have seen other formulas for Kodak HCA which listed more ingredients than just these 2, and even seen the formula called entirely "proprietary". At any rate, this thread and others are not at all kind to Heico Perma Wash. It was not until the late 80's when I finally jumped on the Perma Wash bandwagon, though still reticent about it. In the late 70's and 80's, maybe 90's, Heico Perma Wash was the big deal of its day--a true miracle formula. I have a bottle now I've had for 7 or 8 years, and threw out an older bottle that smelled a very strong ammonia-like smell.
    I never was a true Perma-Wash convert. Having said all this, I wonder if I've gone my whole 42 years since the first time I developed anything, and feeling a bit foolish that a tablespoon of Sodium Sulfite in water is all I ever needed. Heck, I can buy Sulfite by the bushel for peanuts. And I'm beginning to wonder if I should just do that.
     
  26. MattKing

    MattKing Subscriber

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    Tom:

    The two ingredient listing is taken directly from the back of a Kodak packet. I probably should have added the word "active" before "components" because as noted earlier in the thread there are also components designed to deal with hard water.

    You probably aren't doing this, but are you sure that you aren't confusing Kodak Hypo Clearing Agent with Kodak Hypo Eliminator? The latter, which is long discontinued and now considered to be unwise to use, is very different than HCA. There is information about that earlier in this thread as well.

    The Kodak packaged stuff (or similar competitors' products) has advantages flowing from the precision of its makeup and accuracy in use when mixed and diluted per instructions. Those advantages are essentially advantages of convenience and predictability. If your water isn't too unusual, have a source of quite pure Sodium Sulfite and are able to be sufficiently precise in its "tablespoon" use, there really is no reason not to use that alternative.