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Thread: Pot Bromide 10%

  1. #21
    c6h6o3's Avatar
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    Quote Originally Posted by Sal Santamaura View Post
    I don't think so. Jim shoots TMY (perhaps now TMY-2), so he's probably got lots of straight line curve for highlights regardless of increasing his exposure. Jim?
    I find that I get deeper blacks, and for some reason a nicer print color when I use my combination 300 watt light bulb and space heater. But if you can't tell any difference, I'll try a smaller wattage. Those 300 watters are getting hard to find. Thanks for the tip.

    And you're right about TMY. It has a lot more straight line than any paper can handle. Its characteristic curve is quite similar to that of Super XX. Personally, I wouldn't trade TMY or TMY-2 (I have both) for Super XX. I'm astonished that so many photographers prefer a non T-grain film. T-grain seems to me to be quite the superior technology.
    Jim

  2. #22
    c6h6o3's Avatar
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    Quote Originally Posted by Sal Santamaura View Post
    I have many thousand sheets of Azo stockpiled. When I print on them using a 40-watt bulb in a 10-inch Smith Victor reflector with attached diffuser (18 inches above the frame), using negatives developed in non-staining developers, my times are around 20 - 25 seconds.
    So if RPippin is getting overexposed prints at much shorter exposure times with a non-diffused 30 watt bulb, wouldn't you agree with me that his negatives are probably thinner than yours?
    Jim

  3. #23

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    Quote Originally Posted by c6h6o3 View Post
    So if RPippin is getting overexposed prints at much shorter exposure times with a non-diffused 30 watt bulb, wouldn't you agree with me that his negatives are probably thinner than yours?
    Yes, but if he simply exposes his negatives more without changing film development time, I don't think he'll see any difference in the prints' appearance, unless the original negatives were not off the film's toe. Otherwise, only his print exposure times will increase.

    PS One difference in his prints might be that paper area outside the image is blacker. No impact on the low image values though.

  4. #24
    c6h6o3's Avatar
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    Quote Originally Posted by Sal Santamaura View Post
    Otherwise, only his print exposure times will increase.
    Yeah, but isn't that what he wants? I think his original complaint was that the times he had to use were too short to give adequate control.
    Jim

  5. #25
    RPippin's Avatar
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    The bulb I'm using is a 300 watt R40 that was recommended by another contact printer from Richmond. it sits 40" above the print frame in a flood light housing. I haven't had time to get back in the darkroom till now (shot the wedding from hell this weekend), but I'm going to start over with a exposure test, proper soup, and see what kind of times I get then.

  6. #26

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    Quote Originally Posted by Sal Santamaura View Post
    ...Otherwise, only his print exposure times will increase...
    Quote Originally Posted by c6h6o3 View Post
    Yeah, but isn't that what he wants? I think his original complaint was that the times he had to use were too short to give adequate control.
    Indeed, but, as post #20 indicated, in my experience a much lower level of print exposure illumination is appropriate. If the negatives are somewhat thin but still off the toe, why change anything about their exposure and development? Simply using a low wattage bulb for printing seems more straightforward.

  7. #27

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    No one answered the first question properly. To get a 10% solution of KBr you mix, say 50 grams of KBr to 450 cc of water. Then you add water to 500 cc. If you mix 50 grams to 500cc of water you will not have a 10% solution.

    Printing problems. RPippin, I wonder why you did not post this on the Azo Forum. I could have answered your questions, solved your problems, very quickly.

    But you can trust what c6h6o3 writes. He makes the most beautiful prints.

    Michael A. Smith

  8. #28

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    Quote Originally Posted by RPippin View Post
    How long is the shelf life?
    Richard,

    KBr lasts forever. It will take years to go through 500ml of the stuff with Amidol. After 5 years, I've almost run through my 1st 500ml.
    John Bowen

  9. #29
    Ian Grant's Avatar
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    Quote Originally Posted by Michael A. Smith View Post
    No one answered the first question properly. To get a 10% solution of KBr you mix, say 50 grams of KBr to 450 cc of water. Then you add water to 500 cc. If you mix 50 grams to 500cc of water you will not have a 10%
    Michael A. Smith
    That's what I said in the 3rd post in the thread

    Ian

  10. #30

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    Ian, Sorry to quibble, but you said " . . . or 10g to 100ml water." That will not give you a 10% solution. If you add 10g to 90ml of water and then, after it is dissolved, add water to make 100ml, then you will have a 10% solution.

    If you add 10g to 100ml of water the end result will be a solution that is more than 100ml and you will have a slightly less than 10% solution.

    In practice, especially with only 10g, the actual percentage of the solution may not matter, but if we give advice here, we ought to be accurate.

    Michael A. Smith

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