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  1. #1

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    Playing with sulfur sensitization

    Hi everyone,

    After reading PEs book several times I thought I would take an emulsion recipe and try to sensitize it with sulfur. I was going to make The Light Farm's amonium bromide recipe. Maybe it is not appropriate to try and sensitize this recipe and that could be part of my problem. I mainly want someone to check to see if I calculated the proper amount of sulfur. I see there are previous threds on this but I would like someone to check how I did this and figure out my horrible mistake.

    So the recipe calls for 5 grams silver nitrate. I figure silver nitrate is about 169.87g/mol and silver is about 107.87g/ mol or about 64% the total mass of silver nitrate. In 5g Silver nitrate there is about. 3.2g silver. 3.2g Ag/107.87 is approximately 0.03mol Ag.

    PEs book suggests sensitizing with 100mg Na2S2O3/1 mol Ag. So 100mg x 0.03mol Ag = 3mg hypo.

    To get 3mg hypo I disolved 1g hypo in 100g H20, a 1% solution. I then took 1g of this solution and mixed it with 10g water to make a 0.1% solution. I think this would give me 1mg hypo in 1g H20. I added 3ml of this solution to the recipe after washing and then cooked for 60 min as directed in the recipe.

    The result was total and complete fog. Black! I made this recipe without trying to add sulfur and it worked just fine. Very little fog and a very nice emulsion. So I am thinking my math is way off or it is not appropriate to try and sensitize this recipe for some reason. I also expect various recipes need different amounts of sulfur and it is not a one size fits all sort of thing. I also realize trying to measure 1g is a problem as I dont have a great scale but I think I am close. I thought i might have problems but I was very surprised with how absolutely black the plates turned out. I could use these as welding goggles no problem!


    Any help is much appreciated as always.

  2. #2
    dwross's Avatar
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    Hi John,

    I've never sulfur or sulfur+gold sensitized my ammonium bromide recipe. It's meant to be super basic, simple and essentially foolproof. It's the recipe I whip up to keep my Rolleiflex filled and with me always. But, I can't think of a reason sulfur+gold wouldn't work with it. Also, I've never sulfur-only sensitized. I figure if I'm going to go the trouble and have to watch my time and heat like a hawk, I might as well get the most bang for the buck .

    If you get the time and interest, you might try this recipe: http://www.thelightfarm.com/cgi-bin/...ent=29aDec2011
    Starts there and goes for three pages. The recipe is on the third page. There you'll find instructions for a sulfur+gold sensitizer (my adaptation of Steigmann's formula) that will probably work for any recipe of similar nature.

    Hope it works for you as well as it has for me.
    d
    www.thelightfarm.com
    Dedicated to Handmade Silver Gelatin Paper, Film, and Dry Plates.

  3. #3

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    Thank you Denise. I just got all the ingredients for your Steigmann's and your recipe is next on my list to try. I was just in the midst of reading PE's book and playing around with your ammonium bromide recipe and thought what the heck I might as well try throwing in some sulfur! Needless to say I had less than encouraging results. I just could not think of a reason why it would not work.

  4. #4
    dwross's Avatar
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    John,

    Well, now you've done it. You've set loose a bumblebee in my brain. I'm going to make AmBr with Steigmann's tomorrow. I'll be able to let you know how it works on Monday or Tuesday. Do you have preference for colorblind or ortho?
    d
    www.thelightfarm.com
    Dedicated to Handmade Silver Gelatin Paper, Film, and Dry Plates.

  5. #5

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    Hmmmm....... Ortho I think. Neat. I am excited to hear how it turns out. I probably wont get to try your recipe until next week. It is finally showing signs of spring in Duluth and garden work and a bit of plumming are on my list for the next few days.

  6. #6
    dwross's Avatar
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    Excellent! It will be great fun to compare results. Dialogues are so much more productive than monologues .
    d

    p.s. Glad you like the AmBr recipe.
    www.thelightfarm.com
    Dedicated to Handmade Silver Gelatin Paper, Film, and Dry Plates.

  7. #7
    wildbillbugman's Avatar
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    Hi All,
    I have been using Steigmanns for my NH4Br/I emulsions for some months now. I see no reason to NOT do it. Before reading the above reports I was thinking of posting what I found yesterday. A Br/I emulsion I made was showing what I thought to be fogging. But when I turned off the little Bright Lab Jr. Safe light (red safe light about 3 feet above coated and dried plate) and left the coated and dried emulsion in a tiny amount of ambient light, the "fogging" went away. I now realize that some emulsions that I had discarded as "fogging" were simply sensitive to safe lights.
    Just my two cents. To keep everything in perspective, none of my emulsions contain gelatin. Just to be Stubborn, all of my emulsions are based on silane functional PVA. I have used this as a base for Pt/Pd/ Au printing, as well as dichromate/ pigment printing and Carbon Tissue. I guess I am stuck on it. And stuborn.
    Bill

  8. #8
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    Yes you can sensitize that emulsion with Sulfur or Sulfur + Au. The problem is that each emulsion takes a different quantity of sensitizer solution or time or temp.

    The simplest way to test "finish" level is to heat a tiny amount of emulsion to 60C and then place 1 drop on a blotter. Add the appropriate amount of sensitizing solution for the quantity of emulsion. Wait 10mins and take a 1 drop sample and place it on the blotter next to the last one. Continue every 10 mins for 1 hour and then develop this.

    The appearance of fog is the indication of the fact that the emulsion is overdone. Back off 5 or 10 mins and you have the correct time.

    See the figure, courtesy of Nick Brandreth.

    The correct time for this emulsion is about 15 mins for the best speed and fog. It is my latest brainstorm, and Nick is working with it to learn the ins and outs.

    PE
    Attached Thumbnails Attached Thumbnails finish series.jpg  

  9. #9

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    Thank you Denise, Bill and PE. I remember reading about the blotter test in a different thread and forgot about trying it when I got the bright idea to toss sulfur into this recipe.

    Since I had this batch of totally fogged emulsion I thought I would try the PMT just for the heck of it since i never used the stuff before. You are right PE that it it a VERY powerful anti fogging agent. I actually got crystal clear plates after adding it to the completely fogged emulsion. The film speed went down to nothing but it certainly worked. I am thinking I need to be a bit more controlled in my future endeavors.

  10. #10
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    Start PMT at about 1 mg / mole of Silver.

    Go up from there until fog goes away. You will have some speed left.

    PE

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