Carbon Printing - Toxicity

Discussion in 'Alternative Processes' started by L Gebhardt, Mar 22, 2010.

  1. L Gebhardt

    L Gebhardt Subscriber

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    I am thinking of taking up Carbon printing. This is something I have been thinking about for quite a while, but haven't made the push to start primarily because of concerns about the chemicals (Potassium Dichromate).

    I am on a septic system and worried about poisoning myself or the ground water. Can this be done in a safe and environmentally sound manner? What steps and precautions would need to be taken.

    I do have a local hazardous waste collection every couple of months during the warm weather. I don't think it would be feasible to haul all my wash water there however. But I could certainly collect small amounts for processing.

    I also do not have a fume or dust hood, so I am worried about mixing the chemicals because of the dust.

    Are my concerns justified? Any tips on how to do it right?
     
  2. Vaughn

    Vaughn Subscriber

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    You won't need a fume or dust hood. The dichromate is more of a crystal form rather than a fine powder. Wear a dust mask if you are overly concerned. You make a stock solution, so one is not always using the raw chemical. Also the dichromate does not enter the air via fumes (when, for example,, spirit sensitizing.

    I prefer to spirit sensitize -- using only the amount I need for each tissue (rather than making up baths of dichromate of different strengths that eventually can go bad and one has to deal with solutions of dichromates to get rid of.)

    Not enough in the wash water to even think about -- most will come out in the transfer bath and the development baths.

    There are ways to change the form of the dichromate from the most toxic form to a less toxic form. I am not familiar enough with that to discuss it further. You can set the transfer bath outside and evaporate off the water to reduce volume.
     
  3. Loris Medici

    Loris Medici Member

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  4. sanking

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    Like Vaughn I spirit sensitize by brushing a mixture of dichromate + acetone on the tissue. Very little is needed, and you are working with very dilute solutions of dichromate, from as low of about 0.5% to a high of about 10%. To sensitize a sheet of tissue 14X20" in size I use only about 20 ml of a 6% solution of dichromate, diluted 1:1 with acetone. If you like it is possible to neutralize the solution but frankly the amount of dichromate used is so small I don't think it is necessary. There is certainly no risk of damage to a septic tank system with the amount of dichromate used in carbon printing as I have been using dichromate in my home for more than two decades.

    Sandy King
     
  5. PVia

    PVia Member

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    The best solution, and the one I practice for gum printing, is to capture all dichromated water and bottle it for hauling to a waste site. Same as you should be doing for fixer and the rest of your chems...

    Not familiar enough with carbon process to know about wash water, but with gum I collect the first wash water as well as brush/dish cleaning water.
     
  6. sanking

    sanking Member

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    I have for a long time promoted spirit sensitizing because of the very small quantities of dichromate that are used because it makes sense from an environmental point of view. For most of my work it takes about 1.0g of dichromate to sensitize a 14"X20" tissue. If one were to make a hundred carbon prints this size during a year the total amount of dichromate used would be 100 grams, or less than a quarter of a pound.

    On the other hand, some methods of sensitizing use a lot more dichromate because much of it is wasted and goes down the drain. I would encourage anyone who takes up carbon printing to look carefully at the various methods of sensitizing that are proposed by different workers and choose one that is as "green" as possible. In the end all of the methods used to sensitize work well when practiced by a skilled worker so it makes sense IMO to waste as little dichromate as possible.

    BTW, dichromate mixed in distilled water is very stable and can be retained for years and years. I have some solutions on hand that are 5-10 years old and are still as good as when freshly mixed.

    Sandy King
     
  7. smieglitz

    smieglitz Subscriber

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    You probably want to check with a chemist on this but adding an alkali (e.g., borax, sodium bicarbonate, sodium sulfite, etc.,) to a used dichromate wash should convert the more toxic hexavalent chromium form to a less toxic trivalent chromium compound. Filter that solution and eventually dispose of any chromate sludge as a toxic solid waste. Then, you could make a trickle tank out of a 5-gallon bucket filled with bentonite cat litter and let the waste solution slowly trickle through that into a drain (or evaporate in the bucket if you don't puncture it and have enough time). The cat litter should chelate (?) any remaining metal from solution if what I've read over the years is sound. You'll end up with a solid waste that needs to be disposed of eventually through a toxic waste disposal service, but I don't think you'd have to worry about the liquid any longer.

    A couple other references:

    http://www.apug.org/forums/forum42/56598-potassium-dichromate-disposal-uk.html
    http://www.cartage.org.lb/en/themes/Arts/photography/photproces/alternativephot/safedichro.htm
     
  8. L Gebhardt

    L Gebhardt Subscriber

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    Thanks all. Seems like it's possible to do this in an environmentally friendly way without hurting myself. So I'll get some stuff ordered.
     
  9. Curt

    Curt Subscriber

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    Where do you intend to purchase the Dichromate? Are you going to order Ammonium Dichromate or Potassium Dichromate.

    As to safety, I use the same skills that I learned in Industrial Chemistry in College. Wear gloves and eye protection. I wear glasses and use a small scale to measure the Dichromate by placing the Dichromate on a small piece of paper. I don't come into contact with the Dichromate in this practice as I do it in my darkroom alone with the door closed. No people, distractions and no wind. Since there is so little used there is little washed down the drain at the end of the process.

    As a side note I was talking to my neighbor and trying to explain what a Carbon Transfer print was and he said, "it's like the ball and cap rifle hobby", I said yes, if you make the rifle with hand tools and raw materials first. Hobby, I don't think so.
     
  10. sanking

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    You should also plan to wear protective gloves (latex or nitrile) when immersing your hands in water solutions that contain dichromate, as for example when mating the sensitized and exposed tissue to its final support. The very weak dichromate solutions are not toxic at this point but they can cause severe dermatological problems over time if you work without gloves.

    I would also recommend wearing the gloves when you develop the image in warm water. Repeated dunking of your hands in warm water will wash the protective oils from your hand and may cause cracks in your skin. In the past when I did not use gloves in warm water development I would get painful fissures around my fingernails.

    Sandy King
     
  11. Colin Graham

    Colin Graham Member

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    Incidentally, a drop of super glue works really well for those cracks. I get them every winter, they really are remarkably painful.
     
  12. sanking

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    Colin,

    Awesome tip and one that I am sure to try. Last week I had a workshop student here for three days and even using gloves my hands were in the water so much I developed several of these small fissures on both hands by the end of the workshop. As you remark, these small fissures can be very, very painful. I can remember times being in such pain that that I would rub a thick layer of cortisione cream on my hands and sleep with rubber gloves.

    Sandy King
     
  13. Curt

    Curt Subscriber

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    Go to the drug store and get a product called "New Skin" liquid bandage antiseptic first aid bandage for small cuts and wounds. It comes in a brown bottle with a brush in the cap. Don't use super glue, this is the product to use, it will stay on and is skin safe.
     
  14. Colin Graham

    Colin Graham Member

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    Sandy,
    I've been there! I've tried sleeping overnight with bag balm and gloves, nothing much seems to help. This year was especially bad. A drop of superglue and pinch the cut shut and it's like it never happened, the pain disappears instantly too.

    FWIW, a nurse practitioner gave me this tip, so I'm fairly sure it's safe for light cuts, but if anyone has any info to the contrary please sing out.
     
  15. Curt

    Curt Subscriber

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    As I said the New Skin is a product made especially for this kind of injury to the skin. I know truck mechanics who use electrical tape to close gashes on their hand and arms too, what you choose is up to you.

     
  16. Vaughn

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    Actually, from what I understand this is exactly what SuperGlue was invented for -- glueing wounds. Years ago, they used the official medical grade stuff on one my boy's scalp. One of his brothers swung around my crutch (knee surgery) and caught Calder on the top of the head with the butterfly nut for adjusting the length the crutch. Had to wait for my wife to get home as I could not drive yet.

    But I will have to remember this. In the summer when I go barefoot or with sandals, I can get big cracks on my heel -- painful. I'll just glue those suckers closed next time!

    Vaughn
     
  17. Colin Graham

    Colin Graham Member

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    Thanks, I have tried New Skin- it's more of a liquid bandage. It didn't close the cuts at all, washed off easily, stung during application and it was expensive.

    For the record- the Dermabond you reference in your quote is something different altogether- that's a medical grade superglue. It looks like it's available by ER only-
    - http://www.dermabond.com/product/how-it-works.html


    Vaughn, you're spot on- looks like one of the first practical applications was as field dressing in Vietnam.
    Also, here's a interesting tie in with photography-

    http://en.wikipedia.org/wiki/Cyanoacrylate

    Discovery

    Cyanoacrylates were invented in 1942 by Dr. Harry Coover and Fred Joyner of Kodak Laboratories during experiments to make a special extra-clear plastic suitable for gun sights[3]. Although not appropriate for the gun sights, they did find that cyanoacrylates would quickly glue together many materials with great strength. Seeing possibilities for a new adhesive, Kodak developed "Eastman #910" (later "Eastman 910") a few years later as the first true "super glue."


    Forgive the OT sleepwalking ramble, but if it wasn't for insomnia I'd have nothing to talk about at parties! :-D
     
    Last edited by a moderator: Mar 25, 2010
  18. cdholden

    cdholden Subscriber

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    foot care

    Vaughn,
    Get some friar's balsam and cover with Leukotape. Long summer walks just got better.
     
  19. sanking

    sanking Member

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    I developed two more of the painful fissures after some darkroom work a couple of days ago. I tried New Skin on one of them and Super Glue on the other.

    Of the two I believe that Super Glue worked the best for this problem. The glue filled up the fissure, hardened, and did not wash off.

    New Skin also worked OK, but did not dry as hard as Super Glue, and did not stay on my hand as long.

    Both products stopped or relieved the pain from the fissures while they filled the crack.

    Sandy King
     
  20. Vaughn

    Vaughn Subscriber

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    Why does this sound like Robin Hood Meets the Blob!? :D:wink: I'll have to check it out...but it sounds like Super Glue gets put into the various first aid kits we have!

    Vaughn