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  1. #21
    Photo Engineer's Avatar
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    Barry;

    You forgot one.

    Safe Disposal! All solution and wipes and gloves must be disposed of as extremely hazardous waste. Even the final wash water is hazardous until all cyanide is washed out of the coating.

    PE

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    Is using Sodium Thiosulpahte so bad? I know that the image is lighter, but why can that not be dealt with through exposure? Seems a lot less hassle..? K
    Kal Khogali

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  3. #23

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    Quote Originally Posted by Shangheye View Post
    Is using Sodium Thiosulpahte so bad? I know that the image is lighter, but why can that not be dealt with through exposure? Seems a lot less hassle..? K
    My interest is in the silver itself being lighter. This is important in having sweet ambrotype where the negative appears as a positive because of the contrast between the silver and a dark backing material.

    I've got nothing against sodium thiosulfate In fact, we are good friends and have spent many a long night in the dark togeather

  4. #24
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    Quote Originally Posted by Photo Engineer View Post
    Barry;

    You forgot one.

    Safe Disposal! All solution and wipes and gloves must be disposed of as extremely hazardous waste. Even the final wash water is hazardous until all cyanide is washed out of the coating.

    PE
    Yes. I should add the remediation of the used KCN solution with hydrogen peroxide before disposal and/or disposal as hazardous waste. I'm not sure the low residual concentration of KCN on gloves or in wash water warrants disposal as hazardous waste, but that's an option.

    There are very fine wet plate artists using hypo or ammonium thiosulfate as fixers with superb results. However, the wet plate process is a delicate balance of materials and processes--and I achieve superior tonality using KCN. KCN also has a very high fixing capacity at a low concentration (1% compared to 20% for hypo) and washes out quickly.

    It's likely that KCN will no longer be generally available to US photographers within 12 months. Chemsavers will discontinue distribution once their current stock runs out and at this point, I don't know of any other distributor that will sell to individuals.

  5. #25

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    Quote Originally Posted by Barry S View Post
    Yes. I should add the remediation of the used KCN solution with hydrogen peroxide before disposal and/or disposal as hazardous waste. I'm not sure the low residual concentration of KCN on gloves or in wash water warrants disposal as hazardous waste, but that's an option.

    There are very fine wet plate artists using hypo or ammonium thiosulfate as fixers with superb results. However, the wet plate process is a delicate balance of materials and processes--and I achieve superior tonality using KCN. KCN also has a very high fixing capacity at a low concentration (1% compared to 20% for hypo) and washes out quickly.

    It's likely that KCN will no longer be generally available to US photographers within 12 months. Chemsavers will discontinue distribution once their current stock runs out and at this point, I don't know of any other distributor that will sell to individuals.
    I had read that on an MSDS sheet. But wasn't sure exactly what that entailed. Good to know. I'm hoping I can stop by a chemical dealer in person and use my good charms on them. I also have some contacts at the university level that might be willing to act as an intermediary. I would prefer to have a chemistry dealer willing to sell to me. Makes getting uranium nitrate easier

  6. #26

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    PLEASE don't use this. I handle KCN (both the salt and in aqueous solution) at work in a lab and the safety precautions we have to take are immense. The quantity of cyanide you're talking about using is enough to kill 10 large men.
    The LD50 of KCN is about 6mg/kg. It's not worth the risk. Death occurs within minutes, and it's not pleasant from what I've read (not a great way to kill yourself, accidentally or deliberately).
    If you do insist on using it, it's denatured by bleach, so have a large quantity of that to hand and soak everything that might be contaminated with KCN or KCN(aq) in it for at least 2 days. It produces some sort of gas and is very exothermic. I don't really want to know what the gas is. (Sodium hyposulphite, I believe is what we use in the labs - I'll have to check, which is a primary ingredient of... oh yeah, NORMAL fixer!). Wear thick rubber gloves, with latex gloves underneath to enable safe degloving and use in a well ventilated place, preferably a fume cupboard. Wear face protection (e.g. a welding mask) and make sure you always have a second person present when you are using it. Do not even think of having it anywhere near acid, and do not store aqueous solution- it degrades to HCN when in solution, which is a lot more likely to kill you, since you might breathe it in inadvertently.

    To put this bluntly, Potassium Cyanide is really not something you want to frick around with, and which should be avoided if at all possible.

    Sorry if I appear patronising, but I handle the stuff fairly regularly and it scares the sh*t out of me and all my colleagues when we have to handle it.

  7. #27
    Cor
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    Ok,

    Now my part: the use of KCN is a hot topic in the Wet Plate Collodion world. I'll just tell my way of working (BTW I work in a lab and thus have easy access to good safety equipment such as a flow hood etc.).

    I make a 1% stock of KCN, thus far I have made 1 batch of 1 liter, in which I have at least ran 70 or so whole plates through. So advantage one is the high capacity.

    Working inside I use a vertical tank with a dipper and a lid just like the standard silvernitrate tank, this allows careful working with a low change of splashing/contaminating.

    Working in the field I bring about 500 ml KCN fixer with me (in a plastic bottle, placed in another plastic container). When I fix I place the plate in a flat tray and gently pour about 250ml fixer on the plate, rock gently (fixing takes about 20-40 seconds), and than carefully drain back the fixer. I believe the amount of fixer in the drained plate is quite minimal. I wash, and discard the wash water in a tank, and bring it back home and flush it.

    As said before: work with gloves and glasses and be focused! Stay away from acids.

    Ok I'll finish with 2 remarks: A famous wet plate worker works bare handed, also puts his hands in the fixer OFF COURSE I WOULD NEVER RECOMMEND this, but he is very much alive and kicking, has been doing it for 15 or more years.

    On disposal: you can use hydrogen peroxide, there should be a YouTube movie about this. Or you can put it in the hole of fire ant colony..as I read once..(this was a lighter note, do not know it was actually really done..;-)..)

    Best,

    Cor

    Oh I forgot: KCN in my hands on WPC has a definitive edge: the resulting image is crispier, and the colour is more creamy than fixed with RapidFix

  8. #28

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    Quote Originally Posted by Barry S View Post
    Yes. I should add the remediation of the used KCN solution with hydrogen peroxide before disposal and/or disposal as hazardous waste.
    Unless you've been trained how to treat hazardous waste, I'd suggest not attempting it. Also, how do you verify that you've properly treated (eliminated all the cyanide, both free cyanide and cyanide complexed with silver) in your waste?

    And it's not going to be a simple as just adding peroxide and all the cynide will dissappear. My understanding for the peroxide treatment, less reactive cyanides such as those complexed with silver may require addition of a chelating agent to encourage dissociation.

    I happen to have a lot of experience with testing for cyanide in an analytical laboratory, and I know it takes a lot of specialized equipment, a few hard to find reagents, and some experience to get accurate results.

    Quote Originally Posted by Barry S View Post
    I'm not sure the low residual concentration of KCN on gloves or in wash water warrants disposal as hazardous waste, but that's an option.
    My understanding is that permissable effluent levels for cyanide are in the 0.2 to 10 mg/L range. You're local authorities will have better specifics than I do.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  9. #29

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    Quote Originally Posted by mattmoy_2000 View Post
    If you do insist on using it, it's denatured by bleach, so have a large quantity of that to hand and soak everything that might be contaminated with KCN or KCN(aq) in it for at least 2 days. It produces some sort of gas and is very exothermic.
    Cyanate ion is produced. Same as when cyanide is treated with peroxide. Bleach and peroxide are both strong oxidizers.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  10. #30

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    Quote Originally Posted by Cor View Post
    Ok I'll finish with 2 remarks: A famous wet plate worker works bare handed, also puts his hands in the fixer OFF COURSE I WOULD NEVER RECOMMEND this, but he is very much alive and kicking, has been doing it for 15 or more years.
    Anecdotal story:

    A boss of mine started a jub at an major electronics test equipment firm many years ago. His new boss, was giving him the tour of the place and as they were walking past the gold plating tanks, the boss drops his new ballpoint pen into the tank. The pen starts to sink into the tank. Keep in mind, gold plating tanks are going to be in the 10-20% cyanide concentration range. The boss pulls his jacket off, slides his sleeve up, and thrusts his hand and lower part of his arm into the tank and retrieves his fancy new pen. He then walks over to the sink, rinses the pen and his arm off in water, and then pull his sleeve back down and puts his jacket on. The tour begins again as if nothing happened. My boss was shocked and amazed...

    Lesson:

    A single big exposure to some concentrated cyanide on your skin may not kill you - especially if you do a good job of washing it off. It's the much smaller dermal exposure for a long period of time, or the smaller oral exposure that is going to be a much greater risk.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!



 

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