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  1. #1

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    Home Brew questions.

    I have read quite a few times that Gadget G. and others use the 'dry measure' method (tsp, tbsp) to quickly make home brew developers. I have tried it and it seems to work fine.

    Is a scale really necessary? Do Kodak, Ilford measure hold that kind of precision in their packaged developers?

    I do have a 505 grain scale for the really small quantities but I like to 'scoop' for the other ingredients. Saves time, is super convenient, but am I risking upsetting a delicate balance?

    -F.
    Last edited by Fred Aspen; 03-24-2009 at 05:33 PM. Click to view previous post history.

  2. #2

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    If it works for you, that's what counts. Good repeatable results are hard to beat.

    Mike

  3. #3

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    I've been using the teaspoon method for years, no problems. In Anchell's "Darkroom Cookbook", there's a section provided to convert most chems from grams to teaspoons.

  4. #4
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    Fred Aspen,
    It seems like your system is the best of both worlds. And, as Mike says, it's consistency and repeatability that count. BTW, I have used a scale at times and the spoon system at times and have never detected any difference.
    John, Mount Vernon, Virginia USA

  5. #5
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    I use a balance when I think the process I'm doing might be more sensitive to variations in weight than the probable error in the volumetric measurements. If I publish a formula with quantities expressed in weights, I actually measured those weights. I didn't start mixing my own until I came into possession of a balance. I used measuring spoons to move the substance from container to balance. After doing that a number of times, I saw that I was using the same number of spoonfuls each time, so published the article "Kitchen Tested Soups" for Petersen's Photographic. There I demonstrated by averaging multiple spoonful weights and computing the mean-square error, along with deliberate mismeasurement of quantities of critical elements of D-76 and photographic tests of the results, that the photographic tolerance was at least as great as the likely measurement error.

    There have been times when I experimented on an idea using volume measurements and determined the weights for the published formula by weighing those volumes. Of course, I tested the weight formula to make sure it gave the same results.
    Gadget Gainer

  6. #6

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    My understanding is that the risk involved in volumetric measures lies in sample-to-sample variability of the raw ingredients. That is, there's no guarantee that a teaspon of Supplier A's metol (or whatever) will have the same mass as a teaspon of Supplier B's metol. Thus, if you start with Supplier A's metol, determine a formula that works, run out of metol and buy some from Supplier B, your formula may suddenly become radically more or less active than it was before. This issue is due in part to grain size. I myself have seen noticeable differences in grain size from two suppliers (in CD-4, IIRC) -- one supply I've got has a fine-grained, powdery consistency but another has much larger grains, almost like small pebbles. That said, I haven't bothered to check volumes and masses on these two samples, so I can't be sure the relationship differs, but I fully expect it would. The same problem can make it risky to use a formula you've found online or in a book.

    That said, lots of people report good results with this method, so if you're happy with the results, you might as well keep on using it. I'd just keep an eye out for changes when you buy more of any item.

  7. #7
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    Grain size can cause weight to vary as much as +/- 10% or greater. I have done the experiment and posted the data here and on Photo Net. However, if you grind your materials to a common size powder, this would "normalize" the grains and crystals from all sources.

    A mortar and pestle is best for this, but ceramic glazed or polished stone units are best, otherwise you risk cross contamination from the porous unglazed materials. A pharmacist supply probably has the glazed type.

    Small variations can increase your problems from batch to batch and let your process run out of control on you unexpectedly.

    PE

  8. #8
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    You do not need an expensive balance to check these questions. It needs be sensitive and repeatable, but if you have a formula for spoon measurements that works with one batch, you can measure the appropriate volume unit with the cheap or even home made balance. When you get a new batch, you can see if the same volume you weighed before weighs the same. The units of measurement may be coins, a set of buttons, thumbtacks, paper clips, etc. I wager that a dime's worth of Metol, a nickel's worth of hydroquinone, a dime's worth of borax, and 4 tablespoons of sodium sulfite in a liter or quart of water will get you a passable D-76.
    Gadget Gainer

  9. #9
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    Quote Originally Posted by gainer View Post
    You do not need an expensive balance to check these questions. It needs be sensitive and repeatable, but if you have a formula for spoon measurements that works with one batch, you can measure the appropriate volume unit with the cheap or even home made balance. When you get a new batch, you can see if the same volume you weighed before weighs the same. The units of measurement may be coins, a set of buttons, thumbtacks, paper clips, etc. I wager that a dime's worth of Metol, a nickel's worth of hydroquinone, a dime's worth of borax, and 4 tablespoons of sodium sulfite in a liter or quart of water will get you a passable D-76.
    ******
    And don't forget two cents worth of good, practical, advice!
    John, Mount Vernon, Virginia USA

  10. #10
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    Well, since this problem has not been resolved by a practical experiment I would say that there is absolutely no proof either way except for my demonstrated variations in wt vs vol between several batches of chemicals with different crystal forms.

    Until that is done then we have no proof whatsoever. I think that Patrick has said it all "passable". If that is what you want, then that is what you will get! But, there is no guarantee that you will get the same result that I will if you measure as he suggests and I measure out the exact formula.

    PE

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