Precipitate in fixer concentrate

Discussion in 'Black and White' started by giverin, Dec 29, 2012.

  1. I've noticed recently that when mixing up fresh fixer, there is some white precipitate in the concentrated fixer. I've just mixed it with water, put it though a paper coffee filter and used it. It seems to work just fine. Should I be worried? The fixer is Ilford Hypam (5 litres) and I've just seen from Ilfords data sheet that they recommend it be used within 6 months of opening. I've been using it for 2 years and it was given to me already opened by someone who was giving up film photography so goodness knows how long it has been opened. I guess that's why its forming precipitate. Its actually quite expensive for me to buy so I'll probably keep using it until it stops working. I suppose if it fails to clear a film I can just buy some fresh fixer and re-fix the film. Has anyone else come across this problem?
     
  2. SCL

    SCL

    The mixing temperature might be off the recommended temperature....that often causes precipitation.
     
  3. Depends if you're in a hard water area. I treated myself to a distillation unit earlier this year and everything is magically cleaner - no precipitates and no spots. If your film is coming out clear in the specified time, the fixer is fine.
    That said, I don't use powder for fix any more. I can fix twenty or so 35mm films in 600 ml of diluted Ilford Rapid Fixer, so it seems a bit pointless faffing around with five litre bottles and all the rest of it.
     
  4. Hi Stephen & H.P. I can see the precipitate in the concentrate before the water is added. I probably wouldn't have bought fixer in 5 litre size but a couple of years ago I bought some patterson tanks from someone local to me who was moving to digital and he kindly gave me 5l of Ilford Hypam, 5l of Ilford paper developer and 5l of Kodak unifix (hardening fixer) which I use for fixing prints. When the Hypam runs out or becomes unusable, I'll probably go back to buying it in 1 litre size.
     
  5. The chief ingredient is ammonium thiosulfate, nickname "hypo". This compound contains sulfur. The hypo is dissolved in water with acetic acid; a mild form of vinegar. The purpose of the acid is to neutralize residual developer carryover. The acid nature of the fixer solution assures that development will stop promptly. This stop action is best if carried out by a stop bath solution preceding the fix bath. This will be a mild solution of acetic acid. Its purpose is to stop development by neutralizing the alkaline developer imbedded in the emulsion as well as fluids on print/film surface. In this way, the working life of the fix bath is extended.
    A preservative is also present in the fix concentrate. This is solution of sodium sulfite. As the fixer concentrates ages, it decomposes. The preventive slows this action and counteracts the formation of a precipitant. As time passes, nothing can prevent the fixer from decaying. As this happens, a fine suspension of "colloidal sulfur" forms. As time passes the fixer concentrate turns cloudy. Likely, the fixer will continue to be robust and it will continue to fix film/paper however, the colloidal sulfur is a super fine particle and it will infuse into the porous gelatin structure of the film/paper emulsion. Should this happen, washing away the unwanted percipient is extremely difficult. If not copiously washed away the negatives/prints fixed in this substandard bath will be of poor quality. Additionally, if the fix fails negative/print will fade/stain over time.
    More gobbledygook from Alan Marcus.
     
  6. When you wrote:
    It seems to work just fine.​
    I assume you mean it cleared the film in a reasonable amount of time (I use Ilford Rapid Fix; a fresh mixture at 1 + 4 clears my film in about 30 seconds.) If so, you have answered your own question; it works.

    I well understand your concern; I, too, do not like unexplained changes in my photo chemistry. You can never go back and take exactly the same photo over again - even landscapes. If you are photographing people, the moment comes but once and is gone forever.
    With film, it is easy to test the fixer; run a clearing test on the film leader before you start to develop. Prints are a bit more difficult. I have had prints start to turn purple a day after I have made them due to bad fixer. At least I had the negatives. It was a simple, but time consuming, process to go back an reprint.
     
  7. If you are keeping this concentrate because discarding it will be a financial hardship, try warming the solution with stirring. This is a super strong concentrate quire near its super saturation point. If the temperature lowers during storage, some ingredients may fall out of solution. If this is the case, heat and stirring probably will save it. If this doesn't clarify the fluid your only choices are to discard or use understating films could be at risk.
     
  8. If there isn't much precipitate, I think your fixer is fine. I would let it settle and pour off the clear fixer, leaving the gunk behind. If there's a lot, I'd be more worried. Then I would use it for film but not for fibre paper since optimum fixing is very important in this case.
     
  9. Hi Alan, the fixer is stored in my outdoor shed where the temperature in winter can be around or below zero degrees celcius so perhaps that is the problem. I'll bring it indoors to warm up and try and disolve the precipitate. Thanks for the advice.
     
  10. Hi John, I only use RC paper and I have some dedicated fixer for that anyway. I'll try Alan's suggestion and see what happens.
     
  11. I had some fixer die from freezing. I was moving and it was in my truck in the winter. It was less than a month old.
     
  12. Alan: I have some large bottles of Kodak fixer that were given to me a while back. So, if I don't dislodge the settled out colloidal sulfur that has accumulated in the bottom, the fixer should be okay?
     
  13. Mark, over my 55+ years in the business, I have discarded countless qualities of chemicals. In other words, if a chemical doesn’t look right, smell right, then down the drain. The exception being monies are tight. OK, I understand, try warming and stirring. If the precipitate remains, test the fixer. In the light, half immerse a piece of undeveloped film. Giggle the film about. The film enters the fix opaque and soon the fixing action causes the film to become transparent. Time this action because a safe fixing time will be double the time it takes to clear. If the precipitant is truly sulfur, the film will clear but film fixed in this solution may be substandard because colloidal sulfur is difficult to wash out of the emulsion. Stuff that remains in the emulsion elevates the film’s turbidity. Added turbidity will induce flare which is a destroyer of contrast. Only you can make the decision, to discard or not.
    Best of luck – happy new year.
     
  14. Alan:
    Thanks. I'll probably toss it. I have plenty of new fixer, and trying to be cheap on the fixer end of things isn't worth it. I hadn't realized that it was colloidal sulfur, and while I did use a batch like that before, I think I just used it for RC paper. Nonetheless, out it goes.
    Over the past few years, I have ended up with a lot of "spare" chemicals from estates that I had to deal with, and the canned DK-50, Dektol and D76 have been just fine. I certainly have enough raw materials to make my own D-23 and D-76 until I retire.
     
  15. Most photo chemicals, especially if unused, will not present a burden to a municipal sewer system. Used fix however contains silver and that is frowned upon. The Federal guideline is 5 parts per million. Many cities are more stringent, 1 part per million. Actually silver is not a problem in photo effluent sources as the silver will almost instantly combine with sulfur from fixer effluent and the result is an inert compound, silver sulfide. However, sewer codes both Federal and local stringently regulate silver because in some other forms it is toxic, and they can't categorize.
    The silver sulfide that results falls to the bottom of the tanks at the sewer treatment plant. If this sludge is tested using nitric acid as the reagent, silver will be detected. Now the value of the sludge is changes, it becomes a burden and not a commodity.
    What is the real problem? You might like to know that our fixer is the same stuff used by tropical fish people to clear chlorine from the waters of their fish tank. Fixer down the drain will cause chlorine to effervesce out of solution at the treatment plant. This is costly as they are required to chlorinate sewage so the bacteria will be killed upon release. A gallon or two of fixer down the drain will forces the municipality to double or even triple their chlorine usage that day. Should they fail to reach the required chlorine level, they face heavy fines (thousands per day). My message is, tiny amounts of unused fix down the drain is likely harmless so meter it out over a week or too.
    Let me add that developers and bleaches are well tolerated at sewer treatment plant. However, they oxidize and go inert thus if large amounts of photo effluent enter the sewer system, this places a high oxygen demand on the treatment plant. The plant aerates all sewage so that the effluent when released will not be taking on oxygen. The added burden from a large photo lab might overtax the sewer treatment plant. If they discharge with the stuff till taking on oxygen it now competes with aquatic life in a river or lake etc. for oxygen. In summer when water oxygen content is low, the this added burden can trigger a fish kill and again the municipality faces high daily fines.
    More gobbledygook from Alan Marcus
    Among other duties, I was a registered environmental engineer in California with a specialty in photo effluent.
     

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