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  1. #1

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    Safelights during emulsion making - I do not get it!

    We all know that we use a safelight of a particular frequency to avoid exposing emulsions or negatives. But we tune those lights to an area that we know our emulsion is not sensitive too. So why are people mixing emulsions in the dark or using IR goggles, if we can use, say, a narrow band 598nm safelight? Is it because we do not know what the emulsion is sensitive too? If so, maybe someone can tell us which chemistry needs which wavelength of safelight?

    Russ

  2. #2
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    Hi Russ,

    I'm not aware of anyone mixing emulsions in the dark or with IR gear, unless they are making a panchromatic emulsion. You have to do panchromatic sensitization in the dark, but for the home darkroom, that's best as a step that comes after an orthochromatic emulsion is made, coated, and dried. It's not sensitive to red light. That's why you can do regular printing with a safelight. I recommend small red LED's. This is where modern has got "traditional" beat. Nothing worse that a cheap old red paint covered incandescent bulb with a bunch of tiny chips in the paint!
    www.thelightfarm.com
    Dedicated to Handmade Silver Gelatin Paper, Film, and Dry Plates.

  3. #3
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    Yes, Denise is absolutely correct. Use red safelights until you get to pan sensitization.

    PE

  4. #4

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    Thank you for the quick response Guys!

    But with Pan emulsions, even then are we saying that all the silver halides can be over exposed with a single band of light of say 589nm, thus corrupting all other frequency responses of the crystals?

    Russ

  5. #5
    dwross's Avatar
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    rwhb12,

    Did you change the wording and direction of your first post? The physics of optical absorption is probably beyond the scope of this forum. It's an interesting subject (at least what I can grasp of it!) but there are still a lot of unknowns, and details down to the nm are important only on a theoretical basis -- useful for research on absolutely pure, single crystal emulsions of a precise given age. I can recommend "The Theory of the Photographic Process" 4th edition, edited by T.H.James, 1977. Even that is probably dated science by now.

    Get a nice red LED and start making emulsions!
    www.thelightfarm.com
    Dedicated to Handmade Silver Gelatin Paper, Film, and Dry Plates.

  6. #6
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    With a pan emulsion, a red light can fog the red component.

    There are 2 ways to get pan sensitivity. Mix 3 emulsions each sensitive to B, B/G, and B/R. A red safelight will fog only the B/R component. However, if you use a pan dye, then red light exposure fogs everything. You see, then the emulsion is B/G/R sensitive all at the same time.

    So, the results depend on the method of sensitizing. At the present time, I know of no dye that will give pan sensitivity on its own. They are used, but not available to us AFAIK.

    PE

  7. #7

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    Thanks guys. Just finished making a batch of emulsion. Everything that could have gone wrong, went wrong, including dropping the container on the way to the fridge! Maybe I might get a result....

    russ

  8. #8
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    Congratulations! You really can't call yourself an emulsion maker until you've made a truly grand mess!!
    www.thelightfarm.com
    Dedicated to Handmade Silver Gelatin Paper, Film, and Dry Plates.

  9. #9

  10. #10
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    Hi rwhb12,

    You've got to make a few messes and you'll make some batches that do absolutely nothing! Just part of the fun.

    Just curious, what sort of emulsion are you making?

    -- Jason
    All this has happened before, and all this will happen again.

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