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  1. #11
    Hexavalent's Avatar
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    Quote Originally Posted by Vaughn View Post
    And us carbon printers toss in a bunch of sugar, too!

    Does the alcohol itself help keep the beasties away (I use about 10ml of 100% isopropyl per 750 ml of glop)?

    And does the exposure time under the UV lights (even tho it is not the deadlier UVC) help kill the beasties?
    Rotten carbon glop is one evil smell! YUK! Had it happen once, and now everything gets a dash of thymol.

    Isoprop is an effective bacteriocial only at higher concentrations (i.e. 70% used in prep-pads), so I doubt it does much for 'glop'. A thin layer of isop floated atop gelled glop does provide a barrier against critters - it can be poured off before use.

    There are plenty of beasties that thrive in full sunlight, so I doubt a typical exposure is going to have a major disinfectant effect. Post-printing hardening with an aldehyde will sterilize a carbon print, it was a fairly common practice in the "old days"
    - Ian

  2. #12
    Photo Engineer's Avatar
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    Vaughn, the alcohol at that level will be rather mild in effect against the beasties IMHO. The UV will not have much effect due to the black blocking power of the carbon (imagewise) but it will also have some effect.

    Thymol, Phenol and Kathon are better, but Kathon comes with some metal preservatives and you just about need EPA approval to use it. You can burn yourself with Phenol, and its sale is restricted in many states. That is why I use Thymol and why I am working to find another preservative.

    These comments about preservative action of IPA and UV are just guesses based on some limited experience.

    PE

  3. #13
    Vaughn's Avatar
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    Thanks -- I just won't count on IPA and the UV. Unless the IPA stands for India Pale Ale, which needs to be taken internally on a regular basis for its optimal effect.
    At least with LF landscape, a bad day of photography can still be a good day of exercise.

  4. #14
    JOSarff's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    As long as the alcohol is not denatured, either can be used.

    PE
    Well, I made a batch of 10% thymol in 95% everclear (what I had) and put 1 drop per 20g of 10% gelatin at 60C and came up with a yellowish lump about th size of a large packing peanut smelling of thymol. It now hangs in my truck as a deodorizer.

    Ummmm, what happened. Gelatin too hot?

    Joe
    Last edited by JOSarff; 02-28-2011 at 05:46 PM. Click to view previous post history. Reason: correct spelling
    There is no such thing as taking too much time, because your soul is in that picture. -Ruth Bernhard

  5. #15
    Hexavalent's Avatar
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    Joe,

    Did you add it drop by drop, or dump it in? If you dump cold alcohol into gelatin, it can coagulate, though FMO, it usually melts/clears within seconds. Was there hardener present? Did you arrange your darkroom into the ideal feng-shui configuration?
    - Ian

  6. #16
    JOSarff's Avatar
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    Quote Originally Posted by Hexavalent View Post
    Joe,

    Did you add it drop by drop, or dump it in? If you dump cold alcohol into gelatin, it can coagulate, though FMO, it usually melts/clears within seconds. Was there hardener present? Did you arrange your darkroom into the ideal feng-shui configuration?
    Drop by drop by drop and the finished gelatin was going into a former hot & sour soup container (washed first). When I saw the lump, I fished it out immediately, not giving it a chance to melt/clear.

    I'm not sure about the feng-shui, is that like foo-young , but our orange tabby Ozzy did wander through and didn't react, so it did pass the CAT scan.
    There is no such thing as taking too much time, because your soul is in that picture. -Ruth Bernhard

  7. #17
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    Joe;

    We use Everclear for a lot of things in coating and making and therefore it should not be the source of the problem. Having denatured alcohols may cause this kind of thing depending on denaturant, and that is why I warned against them, but Everclear has been shown to be safe at rather high levels AAMOF. Did you try a PET scan?

    Seriously, I have no idea. I have never had that problem, but I always add it right after making or preparing gelatin or Silver Halide, and I believe that I have always added it at 40 deg C.

    PE

  8. #18
    Vaughn's Avatar
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    The literature I have read recommends not getting the gelatin over 120f -- about 50C.
    At least with LF landscape, a bad day of photography can still be a good day of exercise.

  9. #19
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    Well, thinking about this for a bit, I realized that I use about 5 - 10 drops in 500 grams of 10% gelatin. So, this is way more than I usually use. Looking back at my notes, this is what I recommended.

    PE

  10. #20
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    Quote Originally Posted by Photo Engineer View Post
    Well, thinking about this for a bit, I realized that I use about 5 - 10 drops in 500 grams of 10% gelatin. So, this is way more than I usually use. Looking back at my notes, this is what I recommended.

    PE
    I pulled the figure from my notes, 6 drops per 120 g of emulsion/gelatin. since I was making plain gelatin to use as diluting gel after the mix, I was adding the preservative.
    There is no such thing as taking too much time, because your soul is in that picture. -Ruth Bernhard

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