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  1. #11
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    Ok, here is a repost of the formula copied from the other post here:
    -------------------------------------------------------------------
    To 90 grams of distilled water, add 5 grams of photo grade gelatin and bring it to 40 deg C. Stir constantly. When dissolved and there are no floaters of gelatin, add 3.51 grams of reagent grade Sodium Chloride (NaCl). (I find dissolving the gelatin first is best)

    Note, stirring should be continuous, and strong, but should not whip air into the gelatin salt mixture. Don't overdo the stirring, but don't underdo it either. Overdoing it will give you bubbles, and underdoing it will lead to a bad emulsion with foggy large grains.

    In another container, dissolve 5.1 grams of Silver Nitrate (AgNO3) in 10 ml of distilled water.

    Bring the gelatin and salt solution to 60 deg C with stirring. Turn out the room lights and turn on a red or yellow safelight, and then add the 10 ml of silver nitrate to the salt solution as you continue stirring.

    Set a timer for 5 minutes and hold the mixture at 60 deg C for 5 minutes then place in a light tight container and place in the refrigerator. This will keep for about 1 month with no deterioration, perhaps longer.

    You can coat this on about any surface with a paint brush if you remelt it at 40 deg C. I suggest a good camels hair brush with loose bristles removed.

    If you have trouble with even coating, add a drop or two of photoflo 200 to the melted emulsion. If you need hardening, add a few drops of 10% chrome alum to the melted emulsion. If you add any hardener, the emulsion must be used as soon as possible or it will set up to a putty like mass.

    Exposure time will typically be in the contact paper range. I've used about 3 seconds to normal room light. You should get a good black image with a contrast of about 2.
    ---------------------------------------------------------------------

    This is not the formula I use, due to the fact that I cannot get the same grade of gelatin that Bruce uses, and I coat using a coating blade for more uniformity. It was a fair starting point though. I hope it works for you.

    PE

  2. #12

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    legal weasels ad nauseum

    Quote Originally Posted by Photo Engineer View Post
    z-man;

    I hope you sue the guy! That is outrageous. And, I hope you recover fully from the attack.

    I'm sorry but I don't have Bruce's formula here, and would have to look it up. I will repost it ASAP, or post a URL for it. It is here on APUG. I should be able to find it.

    PE
    pe-an outrage to be sure and thanx to you and others for your concern-the aid of the nypd and st lukes hospital ems have made it possible for me to still be here to haunt and harrangue all and sundry

    perhaps an email or 2 from interested parties to the chancelar's office of cuny(www1.cuny.edu) or dean occhiogrosso, counsel to the president of ccny(www1.ccny.cuny.edu) will wake them up out of the circle the wagons stance they are at present maintaining

    as a 100% disabled spanish speaking muslim senior, i am a "protected minority" in 4 catagories but the fact is that any body treated as i have been can sue on the basis of rights violations and pain and suffering-to be continued to be sure

    the thread elsewhere on apug where i and others have been censored and had posts removed for expressing our outrage with the racist posts of a apug member re nyc law changes and photographers/videographers, shows that idiocy still reigns supreme everywhere

    pe-stupid question #1:

    take a fixed out unexposed sheet of rc projection paper and 'sensitize' with a typical salted paper agchl solution-now what do you call it ??? is it a gel emulsion? does sufficient penetration of the gel layer by the silver chloride solution take place to call it so/ or does the solution just lay on top of the gelatine?

    your thoughts please

    vaya con dios

  3. #13
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    Quote Originally Posted by z-man View Post
    pe-stupid question #1:

    take a fixed out unexposed sheet of rc projection paper and 'sensitize' with a typical salted paper agchl solution-now what do you call it ??? is it a gel emulsion? does sufficient penetration of the gel layer by the silver chloride solution take place to call it so/ or does the solution just lay on top of the gelatine?

    your thoughts please

    vaya con dios
    There is no such thing as a stupid question.

    I would not call it anything in particular unless it worked.

    Actually, I suspect that brushing on salt, then brushing on silver solution would make a salted gelatin emulsion with very slow speed. I have little experience with this though.

    Sorry I can't be more specific.

    PE

  4. #14

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    Quote Originally Posted by Photo Engineer View Post
    There is no such thing as a stupid question.

    I would not call it anything in particular unless it worked.

    Actually, I suspect that brushing on salt, then brushing on silver solution would make a salted gelatin emulsion with very slow speed. I have little experience with this though.

    Sorry I can't be more specific.

    PE
    so then a precoated support of any kind if the gelatine/gum/starch?/casien/albumin/whatever is then overcoated with the light sensitve components would be the same as if u had mixed the components with the whatever and then coated a naked support?

    or does the interaction of a mix as u compound it make something which is entirely a different animal than a precoated support then over coated with the light sensitve solution?

    i am thinking i will try both ways but if one way is a dead end i would appreciate the waring

    vaya con dios

  5. #15
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    I have no idea what you will get, but it is always fun trying.

    PE

  6. #16

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    [QUOTE=Photo Engineer;489015]
    Actually, I suspect that brushing on salt, then brushing on silver solution would make a salted gelatin emulsion with very slow speed. I have little experience with this though./QUOTE]

    Here's a website about the making of an ultra-fine grain emulsion (~10nm grains): http://cabd0.tripod.com/holograms/id3.html
    Note, the AgNO3 loading comes first, then the halide/dye/reduction sensitizer bath.
    This method provides extraordinarily good speed for holographic emulsions. I assume it might be adapted to photographic applications.

  7. #17

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    bingo bango bongo i aint got to leave the congo

    [QUOTE=Hologram;489323]
    Quote Originally Posted by Photo Engineer View Post
    Actually, I suspect that brushing on salt, then brushing on silver solution would make a salted gelatin emulsion with very slow speed. I have little experience with this though./QUOTE]

    Here's a website about the making of an ultra-fine grain emulsion (~10nm grains): http://cabd0.tripod.com/holograms/id3.html
    Note, the AgNO3 loading comes first, then the halide/dye/reduction sensitizer bath.
    This method provides extraordinarily good speed for holographic emulsions. I assume it might be adapted to photographic applications.
    these links are what i have been looking for-many thanks

    hologram-have you done any of this or similar?

    pe please look over the links on the page linked to here

    my kitchen chemestry is not enuf for this stuff

    i have allready located acetate and mylar precaoted to round out the glass support concept and since they mention such supports in the original paper i am encoureged

    pe - what do you think of the coating methods in the orignal paper?

    Allahu akbar

    vaya con dios

  8. #18
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    I've read this over several years ago, or something like it. It came up in an old Google search on emulsion making that I did way back.

    As I said, I have little personal experience with these methods. I have seen it done though and it does work. That is all I can say.

    The dip in dye method was used for years as a method to spectrally sensitize silver halides. At one time, the preferred method was to add the dye after the halide, not with the halide, as one has to be careful that there is no interaction during crystal formation. That is about all I could add.

    PE

  9. #19

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    Quote Originally Posted by Photo Engineer View Post
    I've read this over several years ago, or something like it. It came up in an old Google search on emulsion making that I did way back.

    As I said, I have little personal experience with these methods. I have seen it done though and it does work. That is all I can say.

    The dip in dye method was used for years as a method to spectrally sensitize silver halides. At one time, the preferred method was to add the dye after the halide, not with the halide, as one has to be careful that there is no interaction during crystal formation. That is about all I could add.

    PE
    did you see the "curtain method" or the other? re glass support coating

    brit speak gets me confused-i think the other mentioned may be the wire wrapped rod method i used every day in the 90's

    pe did you mention a source for those rods somewhere?

    vaya con dios

  10. #20
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    The wire wrapped rod is available from several sources. I no longer have the URL handy but one company is in Rochester, (Webster to be specific). It works well, but is messy.

    The curtain method is good and also messy. I have seen several methods for coating plates. I show one of them in the slide show on making and coating posted in the sticky here in this forum.

    Kodak used what is basically a wier coater with emulsion being deposited on a single large moving plate of glass which was then cut into smaller plates when dry.

    The best plate coatings I have seen were done with the teapot method where a puddle of emulsion is poured into the center of the plate and then the plate is rocked to distribute the emulsion evenly over the plate. The excess is poured off from two opposite corners then.

    This was a production method used early on before Kodak automated the plate coating process.

    PE

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