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  1. #1

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    Scale for Weighing Chemistry

    What's a good scale for measuring out pt/pd and other alternative chemistries? I was sort of thinking of a double-platform scale with a good set of weights. This would help trim costs. But, will it be sufficient?

    I know that a scale like this can only measure weights in quantum increments. But the water or solvent used can be continuously measured in volume, so I should be able to match any concentration that I want.

    What are other scales that people use that are reasonably priced. What level of accuracy do I need? The amounts of chemistry can get pretty small, for example, when measuring amounts of the oxidizer to increase contrast.

  2. #2
    David A. Goldfarb's Avatar
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    Good deals to be had at www.balances.com.

    I have a Toyo 250 pocket scale, which is fine for my needs. It seems to be designed for jewelers and drug dealers.

    Generally, as the scale capacity increases the precision decreases, so something like mine with a capacity of 250g and a precision of 0.1 gram is good for most developers in moderate quantities and emulsions. If you're mixing your own fixer or really large quantities, then you may want a scale with a capacity of 500g or more. When I occasionally need to measure more than 250g, I just measure in two batches. For small quantities, you can put a slip of paper on the scale to hold the chemical, and for larger quantities a paper or plastic cup works. Most digital scales let you zero the scale to subtract the weight of the paper or cup.
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  3. #3

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    This is what I use Neil.

    http://tinyurl.com/dvke5

    Cheap, very accurate and it has a very nice big plate so if things spill they are easy to clean up.

  4. #4
    Kerik's Avatar
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    I use 2 digital scales, depending on how much mass I'm weiging. For small quatities I use one that is 50 gm max with 0.01 gm accuracy. The other is 400 gm max with 0.1 gm accuracy. Take a look at www.balances.com.
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  5. #5

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    You don't need a really accurate(analytical) scale for most things. When you need a precise amount you make stock solutions (like your oxidizer example).

    The biggest advantage of using a digital scale is that you don't have to add tare weight to your measure.
    If you are stuck on analog a triple beam balance is fastest and pretty accurate. It will also measure a wide range of weights.

    http://balance.balances.com/scales/438
    art is about managing compromise

  6. #6

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    Double pan balances usually have a slider for adding weight up to 1 gram.

    Powder scales are reasonable and will weigh out small amounts but may read in grains only requiring you to convert measurements between the english and metric systems.

    Electronic postal scales weight to 1 gram.

    Check ebay for Ohaus or electronic Mettler balances.

  7. #7
    JG Motamedi's Avatar
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    I bought a cheap "myweigh" 100g capacity with .01g accuracy from http://www.oldwillknottscales.com. It works well and is quite small, although it can be a bit temperamental. I think it was $75.

    For larger capacities, I have a triple beam Ohaus which I found in a dumpster outside NYU's chemistry department. No idea why they threw it out as it works perfectly. I suppose it because it wasn't digital...

  8. #8

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    [QUOTE=JG Motamedi]I bought a cheap "myweigh" 100g capacity with .01g accuracy from http://www.oldwillknottscales.com. It works well and is quite small, although it can be a bit temperamental. I think it was $75."

    Are other MyWeigh scales temperamental? There's one for $139 that comes with a plastic cover to avoid wind currents that looks interesting. It also has a 100gm maximum with 0.005 gm descrimination.

    I think I'll probably need to get a couple of scales, judging from what people are saying. One for low weights and one for larger weights.

  9. #9
    JG Motamedi's Avatar
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    Neil,

    I don't have any experience with the myweigh scales other than the one I own (Durascale 100). I bought mine specifically because it was the smallest and cheapest scale I could find which could measure up to 100g with a decent accuracy.

    I should clarify that the problems I have had with it are pretty minor; mostly just an annoying blinking display. The scale likes and needs fresh batteries, so I have gone through two set of 4 AAAs in the year I have owned it. It also needs to be kept very clean, but of course you should keep a scale clean.

    For what it is worth, Myweigh has a lifetime guarantee on most of their scales. I would probably buy mine again.

    jason

  10. #10

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    Quote Originally Posted by David A. Goldfarb
    Good deals to be had at www.balances.com.

    I have a Toyo 250 pocket scale, which is fine for my needs. It seems to be designed for jewelers and drug dealers.

    <snip>
    I have an Ohaus that must be a first cousin to JG's. Works well, very cheap and needs no batteries. Just saying "triple beam" may gain you cachet in certain circles... this scale was ugly though. It seems to to be about the right capacity for weighing out photo chemistry and you can't lose the weights. If you buy a used balance make sure that it has the complete set of weights and the proper pans. I took one in recently that wouldn't balance out and, after cleaning it off, found that the pans (marked "l" and "r" and indeed differing in weight) were swapped. Works fine now and, being a neat little thing, I left it on the counter to be admired. The first person I showed it to however asked me, "how do you set it in eighths"(dude)? Sigh, metric conversions for dummies anyone...

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