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  1. #11
    Photo Engineer's Avatar
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    Kirk;

    I say PU to pE.

    As to the speed increases noted by Neblette, I think that he is rather conservative in his figures. Also, he has not included the very great gain in contrast afforded by sulfur. Sulfur alone can change an emulsion from a grade zero contact paper to a grade 2 enlarging paper with several stops in speed.

    Finish formulas (sulfur + gold) are often as complex or more so than emulsion making formulas. I give "dump and stir" emulsion formulas and "dump, stir and heat" finish formulas, but the real world goes far beyond that!

    PE

  2. #12
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    Oh, I don't know, Ron. I think Kirk has a real flare for the pun. Have you heard his one about dry plates in Oregon? 'Our weather may be wet, but our plates are dry!" Yuh gotta love it.

    re sulfur: If the conversation has moved from film emulsions to paper, 'speed' has an important related issue. My favorite handmade paper is at least as fast as Forte Polywarmtone when I enlarge a 120 negative, sandwiched with an (old fashioned) unsharp mask, to 11"x14". Minutes! Of all the things that are relative in photography, speed is at the top of my list.

    The rub with enlarging onto handmade paper (in my experience) is that the paper doesn't dry flat after it has been coated with emulsion. It takes a contact printing frame to make even contact across the whole of a negative. I don't like really thick, cold press, heavily-sized papers, so I don't know if they dry flatter, and I don't have a vacuum printing frame. I would really love if someone(s) would try out one or both options for enlarging and let us know how it worked out.

    Denise

  3. #13

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    Denise, speaking of Oregon weather - is it raining as much in Newport as it is in Portland? (I.e. a lot!)

  4. #14
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    Yes, drat! And I've got a lightsafe of dry plates begging to be set free. The garden is happy and the fire danger has dropped to zip, so I guess there's a silver lining. But I prefer my silver linings to be emulsion. Ouch! Nope, my punning ability is no match for yours.

    d

  5. #15
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    Well, we had about 7" of rain in 1 month here and 3 - 5" of it fell in 72 hours. Basements flooded and pools overflowed.

    As for the speed issue, I can expose at the same speed as Ilford MGIV paper, so that is not an issue with me. I use papers with high weight for enlargements, and you have seen at least one of these in the class on baryta and one on Strathmore. Mine dry kinda flat, but then maybe adding a humectant like sorbitol might help you.

    You could try a 300# paper. It makes gorgeous prints and lies flat. You can make very nice postcards with it.

    PE

  6. #16
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    Seven inches in a whole month! I didn't realize that Rochester was in a desert. An humectant is the last thing I need .

    Thanks for the tip about little prints. If one were determined to enlarge, I think you could find 3 x 5 inches of flat paper on about any brand of good, mid-weight watercolor paper (except maybe commercial baryta - I'll check that out next time I coat it.) Fabriano Artistico HP would certainly work.

    At this point, it's only fair to admit my bias toward contact printing. Nothing (to my eye) compares.
    d

  7. #17
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    Denise;

    I agree that contact printing has much merit. I just want to point out that the problems for making enlarging paper are minor and can be ironed out (punny?).

    PE

  8. #18
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    Well, we had about 7" of rain in 1 month here and 3 - 5" of it fell in 72 hours. Basements flooded and pools overflowed.
    Denise, Ron & Kirk:

    This has been some great information. Since I live in Santa Fe (typical humidity <10%) feel free to visit.
    To the pun issue, could Kirk unlock the secrets?

    Joe

  9. #19

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    Joe - I can't claim to hold the secrets to a good pun, but I did study under one of the best, and my observation of his skills was that you just have to take every opportunity, especially if it is a real groaner. There's no holding back a pun... And sometimes the best pun is the worst pun.

    Next time I'm in Santa Fe, I'll swing by. It could be a few years though...

    OK - now let's not turn this thread in a real pun one...

  10. #20

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    So to calculate pAg, it's the negative log of the molar concentration of silver. In the SRAD formula posted, it's 130 g Ag to 500 ml water. That's .769 Mol Ag, and 27.7 Mol water, or a concentration of .027, for a pAg of 1.557?

    if We dump that into a liter of water, with other items, and that gives us .769 mol Ag in 83.1 Mol water, or a concentration of .00923, pAg of 2.03.

    Now does this change as the items react? ( I guess it would since the Agbr is insoluble)

    If so, can we calculate how fast?

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