accurate scales

Discussion in 'Darkroom Developing and Printing' started by Larry, Jan 21, 2009.

  1. Larry

    Larry Guest

    hello all,

    I am looking for a scale which measures up to .001 grams accuracy (.
    0001) but is inexpensive (not cheap). I only need to measure up to 50
    grams at that accuracy. Does anyone know where I could find such a
    scale? (Preferably in Canada, BC to be more exact)

    Thanks
    Larry Kriese
     
    Larry, Jan 21, 2009
    #1
    1. Advertisements

  2. That's ridiculous. What makes you think you need that much accuracy
    (0.002% @ 50 g)? Plus or minus a tenth of a gram would be perfectly
    suitable for any photographic purposes.
     
    David Nebenzahl, Jan 22, 2009
    #2
    1. Advertisements

  3. Larry

    Peter Guest

    If I remember correctly, such accuracy requires not only a lot from a
    scale, but also a way to prevent any slight breeze reaching the scale
    as well as a very stable support. If you only require 0.01 gram
    accuracy there are many choices that will weigh 50 grams or less to
    (nearly) that accuracy and sell for less than $30 or so. I see them
    regularly at places where coin collectors congregate.
     
    Peter, Jan 22, 2009
    #3
  4. For darkroom work, or even drug dealing, I cannot imagine needing such
    accuracy. The chemicals you buy, even photo grade, are not that pure, nor do
    they need to be. I use an Ohaus triple beam balance that is good to 0.1
    grams up to about 600 grams, and that is good enough.

    Your exposures are not that accurate. Your apertures are not that accurate.
    Your developing times are not that accurate. Your solution temperatures are
    not that accurate. Film speeds are accurate to only about 1/6 of a stop.

    If it is simply a matter of measuring a small amount of something, make a 1%
    solution of whatever it is and use only a few millilitres of it. Were I
    mixing a litre of some solution that needed only 0.001 gram of something, I
    bet the solution would work the same without it.
     
    Jean-David Beyer, Jan 22, 2009
    #4
  5. Larry

    Larry Guest

    I am making a one gram batch of Kodalk which calls for .692 grams
    borax and .145 grams NaOH. I realize that the ingredients are not
    that pure so there is a margin of error. This recipe does not allow
    for such deviation otherwise I'd be measuring out .69 grams and .15
    grams or less....
     
    Larry, Jan 22, 2009
    #5
  6. Larry

    Larry Guest

    The formula for Kodalk in a one gram batch calls for such accuracy....
     
    Larry, Jan 22, 2009
    #6
  7. No, it doesn't; you're either misreading it, or misinterpreting the
    precision.
     
    David Nebenzahl, Jan 22, 2009
    #7
  8. Larry

    Peter Irwin Guest

    Scales that do what you are asking are expensive and tend to
    require a glass case over the scale. If you are prepared to
    make ten times the amount then you can use a reloading scale
    from a gun store.

    Balance type reloading scales tend to be the cheapest. Mine
    measures up to 500 grains (32.4 grams) with a claimed 1/10 grain
    (6.5 mg) accuracy. It seems to be at least pretty close to its
    claimed accuracy. Electronic scales can read in multiple units
    including grams and generally have readouts to the hundredth of
    a gram. The electronic scales can be less that $100 and I bought
    my balance for about $45 Canadian from a Toronto gun store about
    6 years ago.

    (I don't own any guns, it just seemed to be the cheapest place
    to get the kind of scale I wanted.)

    Peter.
     
    Peter Irwin, Jan 23, 2009
    #8
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.