My chemicals ate air!

Discussion in 'B&W: Film, Paper, Chemistry' started by tkamiya, Oct 16, 2009.

  1. tkamiya

    tkamiya Member

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    I just found out, my less than half full bottle of Dektol and XTOL solutions have the appearance of air being sucked out. That is, the plastic bottles have significantly caved inward. Fixer bottle is unaffected.

    Is this a result of these chemicals absorbing air and as a result creating vacuum inside the bottle? How do I prevent this. These bottles are only few weeks old since mixed to full strength.

    Nearly full bottle is unaffected.
     
  2. Kirk Keyes

    Kirk Keyes Member

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    They didn't eat it. They sucked it up...

    You can displace the air with nitrogen from a gas cylinder - I do that. Or you can use glass and not worry about it as it will not suck the bottles in.
     
  3. Vaughn

    Vaughn Subscriber

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    The term, I believe is "oxidizing" -- combining with the oxygen in the bottle. It is a good sign...it means the cap in on tight and that no air is being sucked in to replace the oxygen.

    For better results, if making a gallon of developer, fill four 1-quart bottles (filled to the top) and start using the fourth which will not be filled quite to the top. Kodak's data guide say that a full bottle of Dektol will last 6 months -- and a half filled bottle will last 2 months (and one day in a tray).

    Other ways to preserve developers is to put in clean marbles to raise the level to the top again, or squirting in an inert gas (heavier than air) that forms a barrier between the developer and any oxygen in the bottle (sold in wine shops).

    Vaughn
     
  4. tkamiya

    tkamiya Member

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    This is something I wasn't prepared for. I purchased all large storage bottles. Is this oxidizing characteristic only applicable to developers or do fixers have the same issue? What is the mode of degradation for fixer solutions?

    More importantly... since I do not process that many negatives or prints in any given months, keeping fresh chemicals handy will be my problem. According to the docs, Kodak fixer (Professional Fixer) has only 2 months shelf life once mixed with water. Would going with Kodafix concentrated solution and mix as needed be better or would concentrated solution will degrade just the same once it becomes less than full in the bottle?
     
  5. dancqu

    dancqu Member

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    Plan Ahead

    Well you could use bottles that don't suck. That's what
    I do. Also, I split solutions to 'session' amounts. I know
    ahead how much chemistry will be needed for any one
    session. In fact split amounts dictate the amount of
    processing to be done. I don't like to waste good
    chemistry.

    Organize your work load. You'll always have at hand
    a full bottle of fresh chemistry. Dan
     
  6. tkamiya

    tkamiya Member

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    Dan -

    Thank you for your input. My only problem at this point in game is that I *just* came back to film photography and I don't have an established protocol or workload just yet. I would, perhaps, invest in collapsible bottles. One 1/2 gallon regular bottle and one 1/2 gallon collapsible to store mixed 1 gallon.

    I expected my (re) learning curve will be steep but I am encountering things I didn't expect - such as this. I'm glad I have a place to ask questions and make my process better though.

    Would someone be kind enough to comment on fixer issue? That is, knowing Kodak professional fixer only lasts 2 months once mixed - are there a better solution? What is the model of degradation for fixers?
     
  7. Ronald Moravec

    Ronald Moravec Member

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    Small one time use bottles. 250 ml for paper developer. 125 ml for film developer.

    Decant 1 liter at a time when you open it into smaller bottles.

    Anytime developer is exposed to air, it deteriorates. Partially full bottles are not acceptable.
     
  8. Kirk Keyes

    Kirk Keyes Member

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    Keep it as a concentrate as long as possible. If you are starting with Kodak Rapid Fixer which is a liquid concentrate, you can mix a portion of the stock bottle that you bought - make 1 quart instead of 1 gallon. Then you still have some concentrate to make the next quart up with. The concetrate will still go bad faster in a partially full bottle, but I think it will last longer than mixing the entire stock solution up into working solution.

    If you are starting with powdered fixer, then I suggest switching to a liquid concentrate for fixer.
     
  9. Vaughn

    Vaughn Subscriber

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  10. tkamiya

    tkamiya Member

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    Thanks everybody....

    One last Q... Fixers... Do they degrade when exposed to oxygen just like developers or is the degradation process different? Please note, I do not reuse chemicals. I use everything as one-shot only so contamination is NOT an issue.
     
  11. bowzart

    bowzart Member

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    I have used wine boxes emptied of wine and rinsed out very well. The mylar bag inside is supposed to collapse when fluid is drawn out. If filled completely full before restoring the cap, there is little or no air to begin with, and the material is so airtight that I've been able to store chemistry, even color developers, often for years. When I started doing this, I couldn't believe how effective those things are.

    It seems that the best boxes come with the cheapest and most horrible wine which I can't stand (Franzia had the good boxes), so I did some searching around and found this:

    http://www.survivalsolutions.com/store/product41.html

    These are very economical, and conveniently hold one gallon rather than five liters. They have the most useful caps, and have the right kind of bags - the silver mylar ones.

    I have sometimes had fixer go bad, but very rarely. When it does go bad, it has been commercial ammonium thiosulphate fixer, which is very concentrated. You don't have to open the container at all; if you wait long enough it will throw down a whole lot of white precipitate. I'm sure that sodium thiosulphate fixer will go bad eventually as well if mixed and stored, but essentially, it's nothing to worry about, within reason. It will last much longer and remain useful, in general, than the manufacturers say. At least, it has always done so for me. Just check it once in awhile. A good way to do that is to see if it will clear a small clipping of film. The leader that is cut off the 35mm roll when loading the tank is perfect for this; doesn't matter if it has been exposed. The test? Does it clear, or doesn't it?

    Developers contain reducing agents which are needed to reduce the silver halides to metallic silver. The reducing agents oxidize during the development process. They are supposed to oxidize, because reduction does not take place unless the other party to the reaction oxidizes. They oxidize quite readily with the oxygen in air as well as with silver bromide. Developers are much more susceptible to spoilage for that reason. Fixing doesn't involve that type of reaction; the fixer dissolves the unexposed halides, leaving nothing in the film that can be reduced, and clearing the film.

    I'm oversimplifying of course, but these methods have worked for me for almost fifty years.
     
  12. Kirk Keyes

    Kirk Keyes Member

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    Although Dancqu loves single shot fixers, I prefer using two-bath fixing. I prepare two 1 liter bottles of fix, and then I write Fix 1 on one bottle and Fix 2 on the other. I then fix the film for 1/2 the time needed to fix with each bottle. I use fixer test solution (a potassium iodide solution) and then I test the first bottle and then when it becomes exhausted, I dump it out, replace the contents with the contents from Fix 2, and then prepare a new liter of fixer for Fix 2. It really is the most efficient way to use your fixer. A lot more effience than single shot fixing from commercially prepared fixers.
     
  13. tkamiya

    tkamiya Member

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    Thank you very much, everybody!

    I think I have my system worked out now... It's a combination of everybody's method.

    XTOL - mix 5 liter -> 1/2 gallon tank full, 1/4 gallon tank full, 1/4 gallon COLLAPSIBLE tank (rotate as necessary)
    DEKTOL - mix 1 liter -> 1/4 gallon COLLAPSIBLE tank
    FIXER - mix 1 liter -> 1/4 gallon tank (check as needed with film clipping)

    I don't need this much XTOL but it only comes in 5 liter bag or larger in US market.
    (I see in Japan, there is a two liter bag. In US, Kodak seem to have eliminated 1 liter bag when sudden failure of solution became an issue and improper packing of 1 liter bag was a suspect)
     
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  15. Akki14

    Akki14 Member

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    Just to let you know, the chemicals didn't "suck" anything - there was a radical difference in air pressure between when you closed the bottle and now. Like, if you close the bottles when it's stormy out, when it's a bright sunny day they'll collapse inwards a bit due to the higher atmospheric pressure.

    Also this means your bottles are rather air tight, in my opinion.
     
  16. tkamiya

    tkamiya Member

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    When something oxidize, doesn't oxygen combine with whatever and therefore, there is less oxygen in the air in the tank reducing the total amount of air in the tank?
     
  17. Akki14

    Akki14 Member

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    Net amount of materials still in bottle, though. There would be no change.

    Except if there was a pressure change containing the materials more tightly into the same space (like a vacuum does).
     
  18. Akki14

    Akki14 Member

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    Also realise that oxygen makes up a small percentage of the air we breathe so the amount used in oxidation is very small and would not cause a change as you describe.
     
  19. ic-racer

    ic-racer Member

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    In a closed container, there is an equilibrium between the pressure of the gas in the bottle and the vapor pressure of the liquid. The vapor pressure of the liquid can change considerably with changes in ambient temp. Thus causing the plastic bottle to 'cave in' when it is cold and 'bulge' when it is hot.
     
  20. Vaughn

    Vaughn Subscriber

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    The bottle "collaspes" because about 21% of the gases originally in bottle no longer exist as a gas (the air we breathe is 21% oxygen). The oxygen has been removed from the air and has combined to form new chemical compounds that are not in the form of a gas. This reduces the pressure inside the bottle (by about 20%), causing the greater atmopheric pressure outside the bottle to push in the sides of the bottle.

    Vaughn

    Assuming the bottle is at room temp when the cap was put on and the bottle is stored at room temp, there would be very little bulging or caving in due to changes in vapor pressure.
     
    Last edited by a moderator: Oct 17, 2009
  21. Kirk Keyes

    Kirk Keyes Member

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    It's true that the total mass of materials in the bottle is the same before and after. But the oxygen consumed in the reaction has gone from being in the air to being in the liquid, and it has changed volume. As Vaughn points out, you start with a not so small 21% oxygen in the air and it drops as the oxygen gets consumed by oxidizing the developer or sulfite in the solution. And that changes the number of molecules left in the "air", so it's volume decreases.

    By the way, I walked into a walk-in refridgerator at work a couple Mondays ago that someone had put several pounds of dry ice into on the previous Friday. The the room was full of "air" but it had about 17% oxygen instead of the 21% my body was expecting. I noticed the taste of the air was odd, and about a minute later, I was feeling a little tight in the chest. I found what I was looking for and left the room, and felt like I was going to pass out about 30 second later. Pretty odd sensation. Good think there was still some oxygen left... At least I now know what being at the top of Everest is like now!
     
  22. Akki14

    Akki14 Member

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    I do not believe that 21% of oxygen manages to get into the chemicals. That's just improbable. Barometric pressure changes is much more likely.
     
  23. jnanian

    jnanian Advertiser Advertiser

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    make sure your bottles have tight caps!
    i had a bottle and the cap wasn't tight
    and i had a heck of a time pulling my
    sink out of it. the time before i used a cork
    in an amber glass bottle ( yeah i know cork isn't
    a good thing to use ) and the next time i went into
    the sacred space, my enlarger was sticking out of the bottle.
    now .. i use a screw-top bottle ( still amber glass )
    and my chemistry goes into a safe ...
     
  24. Kirk Keyes

    Kirk Keyes Member

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    Then think about how many grams of "air" there is in a bottle. One mole of a gas will expand to 22.4 liters at room temp. If there is 1 liter of air in the gallon bottle, then there is 1/22.4 mole of "air" in there, and air being mostly nitrogen and 21% oxygen, we can say there is about 1 gram of air there, so about 1/5th of that is oxygen. So about 0.2 gram of oxygen. It doesn't seem like much of a stretch to me to have the developer react with 0.2 gram of oxygen. THat would be all 21% of the oxygen in the bottle. Not so much when you think of how many grams there are.
     
  25. Kirk Keyes

    Kirk Keyes Member

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    John, I hope that is an air-tight safe!
     
  26. AgX

    AgX Member

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    Kirk,

    but the story goes on: with the next opening, to take some minor volume off, the gaseous volume will, in the worst case, be substituted by new air. So there will be 0.2 gram again.