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  1. #1

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    calibrating scales, mixing chemicals, fixer life?

    hi all,

    i just began mixing my own bulk chemicals. i have been reading all kinds of info and my head hurts a bit.

    how do you all calibrate your scales? i have an old triple beam that i am using but i am not sure if it is anywhere near correct. i heard a long time ago that a nickel weighs 5 grams. can anyone verify that?

    i have sodium thiosulfate that i am making fixer with. this is pretty much a one use fixer correct? i enjoy using my kodak fixer that i can re use until my fixer tester says it is bad. can i mix something like the kodak fixer? what is the receipe? something that i can re use several times? sometimes i just do not want to mix chemicals first, i just want to begin developing.

    so far that is all i can think of. i usually think of more as soon as i post.....

    thanks for the help.

    eddie
    photoshop is somewhere you go to buy photo equipment.


    lens photos here

  2. #2

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    I can't help yoou with the scales, as I use the teapsoon method, but a sod. thio based fixer can be made to be re-used.

    Some really good reading is Anchell's "Darkroom Cookbook".

  3. #3

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    Quote Originally Posted by eddie gunks View Post
    hi all,

    i just began mixing my own bulk chemicals. i have been reading all kinds of info and my head hurts a bit.

    how do you all calibrate your scales? i have an old triple beam that i am using but i am not sure if it is anywhere near correct. i heard a long time ago that a nickel weighs 5 grams. can anyone verify that?

    i have sodium thiosulfate that i am making fixer with. this is pretty much a one use fixer correct? i enjoy using my kodak fixer that i can re use until my fixer tester says it is bad. can i mix something like the kodak fixer? what is the receipe? something that i can re use several times? sometimes i just do not want to mix chemicals first, i just want to begin developing.

    so far that is all i can think of. i usually think of more as soon as i post.....

    thanks for the help.

    eddie
    Eddie, Google the US Mint Coin specifications: According to the US Mint Specs:

    A US Nickel weighs 5 grams

    A US Dime weighs 2.268 grams

    You can also buy sets of calibration weights.
    Tom Hoskinson
    ______________________________

    Everything is analog - even digital :D

  4. #4
    Murray@uptowngallery's Avatar
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    Don't use any coins as old as your cameras/lenses/etc...they're probably worn thin! :o

    jackspcs.com has some recipes
    apug has some somewhere too
    I think even digitaltruth site might too
    heylloyd too
    Murray

  5. #5
    Monophoto's Avatar
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    Quote Originally Posted by Tom Hoskinson View Post
    A US Nickel weighs 5 grams .
    I bought an electronic scale a couple of years ago. The manufacturer offers a set of calibration weights that cost as much as the scale, but the instructions suggested that using a nickel could also be used and confirmed the 5g weight.

    However, it would seem to me that it would be a good idea to standardize on one nickel - find a new one (I would expect the actual weight to diminish with several years of circulation), and set it aside for use as THE reference.


    Hell of a lot cheaper than buying calibration weights.
    Louie

  6. #6
    rwyoung's Avatar
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    The EXACT ABSOLUTE weight isn't terribly important for calibrating your scales. So long as you always use the same scale and the same calibration weight (nickel) the you will be CONSISTENT in your measurements. Once you have standardized your scale, always use the same procedures and your formulas will be consistent from batch to batch.

    This isn't to say you should be using a 12g mass as your 5g calibration weight. You should try to be close to 5g when working.

    As to the hypo, you can re-use it but its capacity is less than the package stuff. Same test solutions work I believe or you can count sheets/rolls.
    Don't sweat the petty things and don't pet the sweaty things! http://rwyoung.wordpress.com

  7. #7
    Murray Kelly's Avatar
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    Very little in photo brews needs as much exactitude as your scales can provide. Your guesses at exposure will be of greater magnitude than differences in developer variances.

    Mostly the only certitude is the developing agent itself (eg phenidone, metol etc.). Lots of folk work with teaspoon amounts and get perfectly repeatable results.

    Put a container on the scales and note the weight. Add 100 ml of water and you will see, most likely, a change of some number which is equivalent to 100g. If it isn't 100 on the scale you will have to work around that number you see as being 100g.

    The 100 ml water is from a calibrated beaker or 10 fills of a 10ml syringe from the pharmacy.

    I would wager that all it needs is is something to establish the 'zero' point and everything will fall into place. Result = happiness. :-)

    Murray

    Quote Originally Posted by eddie gunks View Post
    hi all,

    i just began mixing my own bulk chemicals. i have been reading all kinds of info and my head hurts a bit.

    how do you all calibrate your scales? i have an old triple beam that i am using but i am not sure if it is anywhere near correct. i heard a long time ago that a nickel weighs 5 grams. can anyone verify that?

    i have sodium thiosulfate that i am making fixer with. this is pretty much a one use fixer correct? i enjoy using my kodak fixer that i can re use until my fixer tester says it is bad. can i mix something like the kodak fixer? what is the receipe? something that i can re use several times? sometimes i just do not want to mix chemicals first, i just want to begin developing.

    so far that is all i can think of. i usually think of more as soon as i post.....

    thanks for the help.

    eddie

  8. #8

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    Quote Originally Posted by Murray Kelly View Post
    The 100 ml water is from a calibrated beaker or 10 fills of a 10ml syringe from the pharmacy.
    "Calibrated Beaker" - I've worked with a lot of laboratory glassware and I can say that calibrating a beaker would be kind of pointless. The lines on beakers are typically only +/-5%. You want to use glassware that is "volumetric" - i.e. designed to measure precise amounts.

    I would look on the bay and find one of the "gem" scale dealers that offers calibration weights. A 50 or 100 gram one should be fine for checking your scale. They should not cost more than a few bucks.

  9. #9
    CBG
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    It doesn't matter whether your measurement equipment is perfect or not as long as you have repeatablility. Even if your scale has, for example, a 10% error, your process can take that into account. What you want is for the errors to always happen the same. It will still work fine.

    Here's how. (Note that you don't want to use volumetric measurement when you can reasonably avoid it. Weigh everything practically possible that goes into your chemicals. Especiallly compounding developer.) Lets assume your scale reads too high so you end up with 9 grams when you think you are getting 10 grams. That's fairly unlikely but would not be a big problem. If you have 10% too little metol in 10% too little water - your strength of solution is still exactly right. You just have a bit less of it than you thought. What you want is repeatability.

    Even if somehow, your developer is a bit weak, you will eventually start using a longer developing time to compensate, or modifying the formula to get a bit more rapid action. Once you have consistent results, you can start "tweaking" the process to improve it.

    Best,

    C

  10. #10

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    [QUOTES=eddie gunks;584585]
    "hi all: how do you all calibrate your scales? i have an old
    triple beam that i am using but i am not sure if it is
    anywhere near correct."

    I've a beam balance on the shelf. Switched to an electronic;
    much more convenient and quick to use. Mine is an Acculab
    with 0.01 gram resolution and accuracy, 200 gram capacity.
    Consider such a purchase. With Home brewing capacity
    need not be so great as fresh chemistry is close at
    hand.

    "i have sodium thiosulfate that i am making fixer with.
    this is pretty much a one use fixer correct?"

    Check out TF-2 or A. Adams S. Thio. fix. Both reusable.
    But don't knock fresh fix. The only way I use it; very-dilute,
    one shot. Also those solid concentrates don't go bad. Take
    a long time out and your chemistry will still be good.

    My session of printing to be done is determined ahead and
    both developer and fixer are compounded accordingly. Same
    for film. Nothing goes back into the bottle. Dan

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