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  1. #21

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    Simple azide salts are indeed pretty nasty, but aromatic azides are different animals. Kinda like the difference between simple cyanide salts (like sodium cyanide) and complex cyanides (like potassium ferricyanide). Most importantly, the organic azides are not explosive like sodium azide is.

  2. #22
    Mark Fisher's Avatar
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    Fair enough. I'm just a simple mechanical engineer that hangs out with a few chemists and biologists. I know just enough to say silly things.....
    Your first 10,000 pictures are the worst - HCB

    www.markjamesfisher.com

  3. #23
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    This is the final day ya'll! If you're interested, please send me an email so I can get your order in.

    I do however, hope to buy a little bit extra that will be available after this purchase. The price however, might be slightly higher.
    If you are the big tree, we are the small axe

  4. #24

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    Ah! Almost forgot! Just sent the money your way . . .

  5. #25

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    Is the group purchase for the sensitizer still open? What is a reasonable amount to order, 100 Gm? I'm not yet a carbon printer but would like to do some. let me know by email if I can still join.
    THanks,
    Tony Rustako
    ajr1000@att.net

  6. #26

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    I did some math here.

    In brief, I estimated 6 grams per liter of finished glop.

    I also estimated about 50ml of glop per 9x12 inch tissue. So that's about 20 tissues per liter.

    In principle, 100 grams could allow you to make 16 liters of glop.

    16 liters of glop could allow you to make as much as 320 9x12 tissues.

    Of course, these numbers are all reasonable estimates, and will vary depending on your specific recipe and method, but it's a reasonable guideline.

    Chris was planning on closing the order some time tonight, so I suggest you send him an email soon.

    Check out the end of the first post of this thread for contact info.


    Best of luck.

    --Greg

  7. #27

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    How small a batch is it practical to make? I was thinking of using my DAS initially in experimentation (New colloids, does carbro work with DAS etc.) for which I have no need of 20 or even 5 tissues of any particular mix until I know it works. I'd hate to be wasting large amounts of something this hard to acquire in excessively large batches of test glop.

  8. #28

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    Quote Originally Posted by Orioes View Post
    How small a batch is it practical to make? I was thinking of using my DAS initially in experimentation (New colloids, does carbro work with DAS etc.) for which I have no need of 20 or even 5 tissues of any particular mix until I know it works. I'd hate to be wasting large amounts of something this hard to acquire in excessively large batches of test glop.
    You can make fairly small batches, but it is dependent on how accurately you can measure ingredients. Another alternative is to make a 3% (maximum) stock solution of DAS. Measuring out small quantities of liquid is easier than small quantities of powder, IMO.

    A single 4x5 inch tissue would only require about 10-15 ml of gelatin solution, so maybe only 1-1.5 grams of dry gelatin. And maybe only 60 milligrams of DAS. 2 ml of a 3% solution of DAS is 60 milligrams of DAS. Think carefully about exactly how small of batches you need.

    Another possibility is to not make sensitizer-incorporated tissue. Rather, make a traditional carbon tissue, and tray- or brush-sensitize the DAS onto the tissue, replicating the process one would use for dichromates. This way tests and samples of tissue that are no longer useful to you can be discarded with little cost (pigment and gelatin cost relatively little compared to DAS.) Just something to think about. If you've never carbon printed before, it will take a few tries to get a recipe nailed down.

    Yet another alternative would be to use pre-made tissues (Bostick & Sullivan). Then you can get used to working with the DAS by tray- or brush-sensitizing without the additional complications of making tissue.

    Lastly, DAS is very highly unlikely to work with traditional carbro recipes. Carbro relies on a completely different chemical reaction to harden gelatin than traditional carbon printing. In order to develop a carbro-like process with DAS, you would need find a chemical (or chemicals) that will react in proportion to the amount of silver in your bromide printer to break the azide groups in the DAS which would cause imagewise hardening of the gelatin. Certainly not impossible if you're skilled in chemistry. But it is extremely unlikely that the traditional carbro recipes will work.

    Best of luck...

    --Greg

  9. #29
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    Quote Originally Posted by gmikol View Post
    You can make fairly small batches, but it is dependent on how accurately you can measure ingredients. Another alternative is to make a 3% (maximum) stock solution of DAS. Measuring out small quantities of liquid is easier than small quantities of powder, IMO.

    A single 4x5 inch tissue would only require about 10-15 ml of gelatin solution, so maybe only 1-1.5 grams of dry gelatin. And maybe only 60 milligrams of DAS. 2 ml of a 3% solution of DAS is 60 milligrams of DAS. Think carefully about exactly how small of batches you need.

    Another possibility is to not make sensitizer-incorporated tissue. Rather, make a traditional carbon tissue, and tray- or brush-sensitize the DAS onto the tissue, replicating the process one would use for dichromates. This way tests and samples of tissue that are no longer useful to you can be discarded with little cost (pigment and gelatin cost relatively little compared to DAS.) Just something to think about. If you've never carbon printed before, it will take a few tries to get a recipe nailed down.

    Yet another alternative would be to use pre-made tissues (Bostick & Sullivan). Then you can get used to working with the DAS by tray- or brush-sensitizing without the additional complications of making tissue.

    Lastly, DAS is very highly unlikely to work with traditional carbro recipes. Carbro relies on a completely different chemical reaction to harden gelatin than traditional carbon printing. In order to develop a carbro-like process with DAS, you would need find a chemical (or chemicals) that will react in proportion to the amount of silver in your bromide printer to break the azide groups in the DAS which would cause imagewise hardening of the gelatin. Certainly not impossible if you're skilled in chemistry. But it is extremely unlikely that the traditional carbro recipes will work.

    Best of luck...

    --Greg
    Hey Greg, in your testing did you use water or alcohol as your solvent for the 3% solution? In reading the threads it seems both are viable?

    From someone that's used to working with Potassium Dichromate w/ acetone, is spirit sensitizing with DAS similar?
    Co-Host of The Film Photography Podcast, the bi-monthly internet radio show all about film!

  10. #30

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    I have only made pre-sensitized tissues with DAS/water solution. I've never tried sensitizing tissues after pouring/drying.

    Obviously, if brush-sensitizing with just a water solution, there's no problem.

    I do add some isopropyl alcohol to my sensitized gelatin solution without any apparent problems. But I haven't tested compatibility with brush sensitization with isopropyl alcohol or acetone.

    --Greg

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