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  1. #1

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    Maine-iac's Divided Paper Developer

    does anyone read the article: http://www.apug.org/forums/article.php?a=87

    i just have some question about it:

    1) where to find or who can give a formula represented in grams rather than teaspoons? (how many teaspoons a '1/2 cup' equals to?)

    2) bath A includes no instruction about when to add the water (and it's temperature). should i add it in the first step or last step? i think i need a precise instruction.

    3) does the divided paper developer widely used and stable enough to trust? i want to use it since it's hard to me to control solution temperature during paper development session, but it seems divided development for paper is not well known.

    thanks in advance.

    -
    narke

  2. #2
    Ole
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    2): In all cases start with about 3/4 of the total volume. Dissolve ingredients in the order gives, making sure everything is dissolved before adding the next one. At the end add water to top up to the final volume. That is common to all these recipes with a very few exceptions - and where there are exceptions, they will be noted.

    Temperature should be around 20°C unless otherwise noted.

    3): One thing divided developers will not do is work at all temperatures. You still have to be in the right general area. Say 18 to 25 °C.
    -- Ole Tjugen, Luddite Elitist
    Norway

  3. #3

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    Quote Originally Posted by narke
    does anyone read the article: http://www.apug.org/forums/article.php?a=87
    1) where to find or who can give a formula represented in grams rather than teaspoons? (how many teaspoons a '1/2 cup' equals to?)
    Based on my culinary training, 1 ounce equals 2 tablespoons. There are 3 teaspoons in 1 tablespoon. and there are 8 ounces in 1 cup.

    So in 4 ouces (1/2 cup) there are 8 tablespoons or 24 teaspoons.

    Dan

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    Unfortunately, dry weight of organic and inorganic chemicals does not translate well from volumetric to gravimetric amounts (and vice versa from gravimetric to volumetric). This is one of the fundamental problems with using volumetric measure for solids.

    The 4 oz = 1/2 cup works only if density is 1.0 and is a liquid. For dry measure, density can vary all over the map. Even liquids are often hard to measure volumetrically and that is why gravimetric measure is more accurate.

    I have stated before that I see up to a 20% error in weight from a given volume of material if the material is a powder vs a crystal. This can be far too much for many photographic chemcials.

    PE

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    Quote Originally Posted by Photo Engineer
    Unfortunately, dry weight of organic and inorganic chemicals does not translate well from volumetric to gravimetric amounts (and vice versa from gravimetric to volumetric). This is one of the fundamental problems with using volumetric measure for solids.

    The 4 oz = 1/2 cup works only if density is 1.0 and is a liquid. For dry measure, density can vary all over the map. Even liquids are often hard to measure volumetrically and that is why gravimetric measure is more accurate.

    I have stated before that I see up to a 20% error in weight from a given volume of material if the material is a powder vs a crystal. This can be far too much for many photographic chemcials.

    PE
    so, i wanna know wether or not there is a gravimetric form of the divided formula. i believe somebody has done it.

    thanks.

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    narke

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    Gravimetric to volumetric (and vice-versa) conversion tables are available for common photographic chemicals, but as PE says, these can vary a lot depending on factors like the form of the material (powder vs. crystallized, how finely packed it is, etc.). One place to check is Anchell's The Darkroom Cookbook. From his table (p. 274):

    Metol: 3.0 g = 1 tsp
    Sodium sulfite, anhydrous: 7.9 g = 1 tsp
    Hydroquinone: 3.3 g = 1 tsp
    Potassum bromide: 1.9 g = 1/4 tsp
    Benzotriazole: 0.2 g = 1/8 tsp
    Sodium carbonate, anhydrous: 4.8 g = 1 tsp
    Sodium carbonate, monohydrate: 6.3 g = 1 tsp

    1 tsp = 1 teaspoon
    1 tbsp = 1 tablespoon
    3 tsp = 1 tbsp
    1 cup = 16 tbsp

    This is all US measures. UK measures are slightly different, but I believe the formula you referenced used US measures.

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    Srs, absolutely right, but in actual experimentation I find that there is that 20% variation due to variations in the chemical form from batch to batch which causes density variations.

    Sometimes it is ok, and sometimes it is not. That is why I always use graivmetric. I don't even look seriously at volumetrically measured formulas. Too chancy.

    All serious engineers use gravimetric for solids and volumetric or gravimetric for liquids.

    PE

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    Quote Originally Posted by Photo Engineer
    I have stated before that I see up to a 20% error in weight from a given volume of material if the material is a powder vs a crystal. This can be far too much for many photographic chemcials.
    PE
    You are absolutely correct and of no help at all in answering the questions asked. In the kitchen there can be up to 50% difference and it can be far too much for most peoples taste buds.

    However, it is the answer to answer the question asked: How many teaspoons in a 1/2 cup? In addition, the OP also asked: about a formula in grams. Which was also answered. But thanks for being so accurate.

    Dan

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    Dans, you are right in every resepct, and I did not give an answer.

    The reason is that there is no formula in grams that I nor probably anyone can accurately calculate, and so far no one has given one. It may not exist.

    As for teaspoons in a cup, that was already answered, so I didn't have to repeat it. Any cookbook has that information.

    I'm sorry for not being able to supply the answer. I would like to be able to just to prevent this type of problem. It keeps coming up over and over and over.

    PE

  10. #10

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    okay. these so much disagreements make me hesitate to use the formula. and, i also noticed the ingredients in the formula are very diffferent in quality with Dektol and i can not figure out why. has anyone ever used the formula?

    can i change my question to: is there a popular divided paper developer out here and given in gram?

    -
    narke

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