RE: Need formula for Potassium Ferracyanide

Discussion in 'B&W: Film, Paper, Chemistry' started by mikewhi, Jul 16, 2004.

  1. mikewhi

    mikewhi Member

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    Hi:

    Memory going bad. I haven't used this for bleaching prints in a LONG time. Can someone remind me how this is mixed and used? I have the chemical powder in Kodak bottles. I know I used to mix it in with the fixer and bleach the entire print at once and I used it with cotton swabs and applied it locally on the print. I preferred to use a weak solution sl the bleaching came on slowly and could be arrested before it went too far.

    I also recall this comes packaged with Farmers Reducer, part A I think. Correct?

    Thanks in advance,

    -Mike
     
  2. Aggie

    Aggie Member

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    for the bleaching I do, I learned it from Bruce Barnbaum. The Potassium Ferricynide should be mixed with water to the color of a nice yellow not a strong yellow but a medium one. I do not measure. Get your print wet first then work in good light. Bruce has some nice surgical hosing set up so that he can use a stream of water as he works. I use Japanese calligraphy brushes to apply the bleach. when it is nearing the bleaching in the particular spot that I want, i hurry and put it in a tray of fixer which stops it complete from bleaching further. Use the water stream to keep the bleach solution from flowing into portions of the print you won't want it to go. Slow is good. If you try to bleach too quickly or too much at once you will have a mess. Do little spots at a time and for a little time. Once it has been in the fix, you can rinse it well and rebleach. Oh and Bruce has a nice opaque plexiglass sheet he has at an angle in his developing sink so that when the print is wet he can adhere it to it. It keeps the print at about eye level so that you can get closer to watch the bleaching action. The bigger the brush the bigger the area you can work with.

    If blonde speak needs translation ask what I messed up explaining.
     
  3. ann

    ann Subscriber

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    We have used a 10 % solution of "ferri" with about 5ml of weak fixer for local bleaching.
    There are a variety of formula for global bleaching; are you looking to re-developer after or use of a general lighting?

    One standard bleach formula would be :
    ferri 10 grams
    potassium bromide 5 grams
    water for 1 liter
     
  4. snapnsam

    snapnsam Member

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    I use the process described by Aggie and I'm satisfied with it. One caution, If you use a brush to apply the bleach solution, be sure it doesn't have a metal ferrule.

    Sam
     
  5. happysnapper

    happysnapper Member

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    There is a book for you to find that will give you an idea about the potential for disaster when using Potassium Ferricyanide. It is called, Overexposure, Health Hazards in Photography. You will see that mixing any acid with Potassium Ferricyanide produces cyanide gas, not really a good thing for a long career in photography, albeit a small concentration. You do not need to use fixer, it is an old school way of getting the bleach to act faster (it becomes an accelerant). Be sure before you put your print back in fix after bleaching that you rinse it very thoroughly with water or the residual will suddenly act up again for the same reason. I agree with Aggie fully too, you need to start slowly and patiently, you can always bleach some more. Of course, wear gloves and have ventilation.
    Take a gander at that book too though, it's a good thing to have as a reference in any photo library...
    Good luck, Ray
     
  6. mikewhi

    mikewhi Member

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    Good point, 'happysnapper'. This stuff is poisonous, and I think the bottles I have have the 'skull and crossed bones' on it, even. DO NOT for any reason get this stuff in you. As I understand it, the stuff basically suffocates you by inhibiting blood from carrying oxygen, or something like that. I do recall reading that the guy who made\discovered this stuff actully killed himself with it.

    I have used it in the past, but I didn't go so far as to wear masks or heavy fans in the area etc. I did keep my fingers out of the stuff using tongs all the time.

    It is great tool, just know you're dealing with a poison and take reasonable precautions. Plenty of people have used without killing themselves, and there is no reason you can't be one of them!

    -Mike
     
  7. Aggie

    Aggie Member

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    precautions are one thing, paranoia is another. The cyanide gases given off from the very small amount you would be working with is far less than the chlorine gas given off from a swimming pool. Maybe we should not go swimming in swimming pools.
     
  8. rogueish

    rogueish Member

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    From the Darkroom Cookbook, by Stephen G. Anchell:
    You can use Farmers reducer or Kodak R-4a.
    "Use a strong solution of Farmers or R-4a. For print reduction with R-4a, mix 1 part A, 1 part B and 10 to 15 parts water depending on desired rate of reduction. One methods recommends (Farmers)1 part A to 2 parts B without adding water. If you feel the action is too slow, add a little more solution A. An alternative to Farmers reducer is medicinal iodine tincture. remove the iodine by immersing print in hypo just as you would with Farmers; fix and wash. NOTE" Always use a non-hardening fixer for any after process such as reduction, intensification, toning, etc."
    What is in the book is more detailed of course, but that should help prod your memory lapse.
    As to safety, ALL photographic chems are toxic to one degree or another and should be handled with care and a little common sense. Good ventilation is recommended. Oh, and don't be sipping the brew even it is Farmers brew... :tongue:
     
  9. happysnapper

    happysnapper Member

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    Aggie,
    It is always better to take precautions don't you think? The last I heard, they didn't use chlorine gas to execute people in the gas chamber either. As you bleach, I do believe that you would have your face right down on your print in order to see what you are doing. I don't suppose you have a scale for the proximity effect. Read the book I suggested.
    And stay out of the pool...
     
    Last edited by a moderator: Jul 22, 2004
  10. clay

    clay Subscriber

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    Aggie is right on here. It takes a REALLY strong concentrated acid to cause potassium ferricyanide to release any cyanide gas. The chemical bonds of the iron and cyanide are very strong. Diluted stop bath won't do it. Acidic fixer won't do it. The book you mentioned by Susan Shaw is generally regarded by anyone with any chemistry knowledge as an alarmist, scientifically dubious cut and paste job that makes some wild extrapolations from a pile of MSDS information. Hysteria sells well in the USA.

    The short answer, yes, be careful with any chemical. Don't dip your hands in any solution ungloved. Wear a mask when mixing up dry chemicals. Ventilate your darkroom. Don't eat and drink in the darkroom. But you can relax about the potassium ferricyanide. (potassium cyanide is another matter altogether) Heck, that is the main ingredient in cyanotypes, which is considered safe enough for kindergartners to slop around and make sun prints.
     
    Last edited by a moderator: Jul 22, 2004
  11. mvjim

    mvjim Member

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    I happen to agree with Aggie on the paranoia issue when using PF. I use it everyday and over the years have had a few accidents with it that caused me to panic and call the poison control center in the city and Kodak. Both informed me that at the concentrations that were being used (4oz of water mixed with enough PF to cover the head of a wet Qtip) that there was no concern for alarm. I have read the book mentioned and yes all should be cautious with the handeling of the chemistry that is used. But we should all be realistic as well.
     
  12. ann

    ann Subscriber

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    thank you Clay, i was just beginning to response to this latest "remark".
    That book which was printed in 83 was highly suspect them as is now.

    We work with a lot of "dangerous chemicals", and common sense calls for being smart and having respect for our tools. It does't mean we should not tone, bleach, do alternative process, etc. Nor, does the use of these products mean we are "a bull in the china cabinet", rather we choose to be prudent and work with these tools with intelligence and respect.
     
  13. Aggie

    Aggie Member

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    Thanks Clay, Jim, and Ann. Knowing your backgrounds, I appreciate your responses. I was not advocating NOT taking proper precautions. I have heard so many claims of things being bad over the years that have later been proven to be false, yet once they had been labeled so, the stigma followed forever. Kinda like the dihydromonoxide scare recently in southern California.
     
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  15. Aggie

    Aggie Member

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    IF you use a large opaque white plexiglass sheet to adhere (with water suction) your print for bleaching, You can also add a nice light source that will shine from the back (it can be to one side pointed at the sheet from behind so that it doesn't have to sit in the sink, or any other numerous ways of shining a light from behind) you are thus illuminating the entire print and work area. At no time do you need to get your face right down on the print. If the eye sight of the person is that bad, I suggest getting some glassses or better yet those magnifying lens shades like an optivisor. Most people would have difficulty focusing with their node on the print.
     
  16. Eric Rose

    Eric Rose Subscriber

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    Barnbaum's fingers are all still there, and he's not twitching so given people call him the Acid King I suppose it's pretty safe stuff.
     
  17. happysnapper

    happysnapper Member

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    And don't worry Clay, Jim and Ann, I was not trying to say anything abstract about Aggie's points. I even agreed with her if you noticed. A general comment that is parallel to all of yours about using some common sense and following safe work habits in no way closely implies the doom of toning or alternate process. In fact, I believe that by practicing safety and good sense of craft, you might even be around longer to continue making images.

    As for being an alarmist, I don't know about that term. Cautious maybe. Something about knowing the materials you handle I guess. You guys amaze me sometimes...

    I'm off to look for WMD's.
     
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  18. happysnapper

    happysnapper Member

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    Now I need to ask this....
    If the white plexiglass sheet is opaque, why light it from behind? And why would you want to do that anyhow?

    Just really wondering.
     
  19. Aggie

    Aggie Member

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    Well gosh golly gee whiz. Seems both EricR and I took the workshop at the same time where the setup was used. Bruce Barnbaum uses it daily in his work.
     
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  20. ann

    ann Subscriber

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    I have been doing darkroom work for 57 years and since the age of 21 have had only 6 sick days and that due to surgery. I do have a serious problem with being fingerprinted, all that chemistry for so many years . However, i also know about the chemicals i am using and do use gloves for all toning process and developers i.e PMK.and other toxic chemicals so how you gather i was not knowledable about practicing standard work habits involving toxic materials is beyond me. As an aside I intend on being around and printing for at least another 50 years, with or without WMD's.
     
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  21. Aggie

    Aggie Member

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    I put in a call to an old professor of mine at the University of Arizona (yeah in your neighborhood Robert) I just got the return phone call. The scoop on the toxcity of potassium ferricyanide is this: Yes a toxic gas can be given off from this compound if it is mixed with a strong (HCL or hyrdrochloric acid) acid. When mixed with water, no lethal or life threatening gas is produced. The metal cyanides, iron, cobalt and nickle are the most stable of all the cyanides. He suggested that you wear gloves and work with ventilation. Not for fear of some gas being given off, but as just good lab practices. He also told me not to go sniffing the powder.
     
  22. Tom Hoskinson

    Tom Hoskinson Member

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    Excellent Aggie - hope your reply kills this thread.

    Happysnapper - don't eat the potassium ferricyanide. HCl is an important constituent of your digestive juices.

    Bear Down, Arizona!
     
  23. Ole

    Ole Moderator Staff Member Moderator

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    Yes, HCN (Hydrogen Cyanide) is a very toxic gas. If you ever feel the smell of almonds when toning, you should already have run away.

    But remember that H2S (Hydrogen Sulfide), the nasty smell of sulfide toner, is 100 times more toxic - and far easier to make. Keep all toners away from acids!
     
  24. mobtown_4x5

    mobtown_4x5 Member

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    I have an overexposed neg I would like to try it on. I bought Kodak "Farmer's Reducer" (I would love to know where the name comes from);

    Question: if the PF ("Part A" ) is all you need, what is the point of their "Part B"?



    As far as toxicity, the professor suggest not sniffing the powder, and I agree. I was sniffing for a while, butI have graduated to injecting it and I feel great.
     
  25. Aggie

    Aggie Member

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    quick clarification for those that do not understand about an opaque white piece of plexiglass. When a light source from behind it is turned on, the plexiglas glows from the light. this allows the picture to be gently illuminated for the purposes of bleaching. A translucent sheet would give way to much light and the light around the edges would interfere while looking at the picture. So Yes I do mean opaque.

    This is the sheet of material that I purchased and the company I bought it from.


    http://www.tapplastics.com/shop/product.php?pid=258&sed
     
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  26. ann

    ann Subscriber

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    mobtown;
    part b in Farmer's reducer is typical sodium thiosulfate (hypo). I haven't used pre-package for years and since i don't have the package in front of me i will not guarantee that is what yours is;but i would be surprised if it wasn't hypo.