The ambigity of "dilution 1:3"

Discussion in 'Black and White' started by mtc photography, Jul 16, 2001.

  1. What is "dilution 1:3 "
    In medicine and chemistiry, dilulion 1:3 means dilute one part concentrate with solvent, such that the final volume is 3 part.
    In some photography formularies, however, "dilution 1:3" means
    dilute one part of concentrate with 3 part of water.

    <p>

    In the first case, the concentration is 1:3 or 33%
    In the later case, the concentration becomes 1:4, or 25% of original.

    <p>

    IMO, the usage in some photography writing ( dilute 1:3 as add 3 part water to 1 part stock ) is incorrect
     
  2. I agree - it causes confusion. Typically, in photography 1:3 means 1
    part of whatever is being diluted and 3 parts of the solvent (i.e.,
    you end up with 4 parts of final solution). Richard Henry suggested
    using 1+3 etc as a less confusing alternative but old habits die
    hard, I guess.... Cheers, DJ.
     
  3. a dilution of 1:3 (one to three) means mix one part concentrate with
    three parts water. it doesn't mean mix a 33% solution.
     
  4. I've always read 1:3 as "one to three", which is fairly unambiguous.
    One part of concentrate to three parts water. In other words, a 25%
    solution. You sometimes see 1:1 written as a dilution, and this
    doesn't make any sense other than as a 50% solution.
     
  5. We darkroom denizens have always used some terms in our own special
    way, like referring to chemicals as "chemistry". Years ago I adapted
    the 1+3 convention, as have most photo chemical manufacturers.
     
  6. Many photographers do use dilute 1:3 sloppily as 1 part concentrate
    + 3 part water, one even may see such sloppy usage in some Kodak
    documents<p> But when it comes to serious instruction, Kodak has being
    very precise, for example on Tmax developer bottle " Add one part
    concentrate to 4 part water ", they don't say dilute 1:4
    <p> Ilford instructon is also precise, they say " 1 part concentrate
    + x part water "
    <p> The problem with the usage with slopy photographic ussage of
    "dilute 1:3" as "dilute 1 part to 3 part water" is that it is
    in conflict with the usage common in chemistry and medicine
    where a dilution of 1:3 means one third strength. Before photography
    was born, chemist had already mixing solutions for many many
    centuries.
    <p> Dilution 1:3 indicate a degree of thiness. (See New Oxford
    Dictionary of English )
    <p> Agfa also say " add one part concenrate to 15 part of water"
    <p> So IMo, dilute 1+3(water ) is better than dilute 1:3
    <p> The most strict difintion must be the one followed by chemists
    and pharmacists: dilute 1 part (of A )with solvent to make 3 parts
    <p> Because 1 part in volume of A plus 1 part of same volume of
    solvent does not always result in twice the volume of original, some
    times it may be more, some times it may be less. <p> A good example
    is 100 ml of ethanol plus 100 ml of water yields much less then 200
    ml of dilute, if you want really 1:2 strength, more water is
    needed, otherwise, the dilition is more than half strength. <p>
    Therefore, in
    chemistry and medicime, the quatity of solvent is not important,
    sometimes you don't even know what it is, and don't need to know.
    The important thing is to control the final volume of the dilution.
    <p> In old days, photographic formular was quite strick, they told
    you to add such and such chemicals in 600 cc of hot water, disolve
    completely, then ADD WATER TO MAKE 1000 CC. Why not prepare 1000 cc
    of hot water outright ? Because, the resulting developer will be
    more then 1000 cc.
    <p> Fortunately, in photography dilution mostly refers to acqueos
    solution, and 1+ 3 = 4 parts.
     
  7. Since I am a chemist, I can speak from experience. A dilution
    written as 1:3 has always been 1 part of A mixed with 3 parts of B.
    What may change from time to time is the units of measurement. For
    example 1:3 may be followed with v:v which specifies the unit of
    measurement is volume of each part or 1:3 may be followed with wt:wt
    which specifies the unit of measurement is weight. I would like to
    know the specific example where 1:3 means 33%. I've never seen in
    college or industry.
     
  8. There is nothing wrong if everything is clearly specified like
    stock:water = 1:1 or stock:final volume = 1:2.
    However people tend to assume former in many photographic contexts
    without making it explicit.

    <p>

    I prefer notation 1+(n-1) for 1/n concentration. However, in this
    context one usually restrict n to positive integer, although dilution
    makes sense for any proportion (real number) between 0 and 1,
    inclusive.

    <p>

    It is a bit inconvenient when most formulae are published in metric
    units some tanks and packaged chemicals assume Imperial system.
    Developers like HC-110 and Ilfotec HC usually specify dilution in
    1:(n-1) or 1+(n-1) fashion where n is a power of 2. At the same time,
    some film tanks come in metric scale.
    For example, mixing 1+63 for 1 liter tank requires 15.625 (or 15 +
    5/8) ml concentrate.

    <p>


    In my personal records, partly because the capacities of my tank
    and print slot processor are specified in metric volume units,
    I am shifting into notation like concentration
    0.015 and calibrate time and temperature accordingly. (1+63 dilution
    would be 0.015625 concentration although maintaining five significant
    digits is not practical nor useful) In some cases
    I need to make 473 ml working solution - I can simply multiply 0.015
    and 473 to get approximately 7.1 ml concentrate and WTM 473 ml (yes
    number comes out messy this case).

    <p>



    <p>

    Many formulae still begin with some fraction of water and after
    dissolving everything another water to make the final specified
    volume. Either way, when precision is important chemists specify in
    molarity or other appropriate units, and in most photographic
    applications generally moderate requirement for precision does not
    neccesiate that kind of units.
     
  9. It has never been ambiguous. : refers to a ratio. Not necassarily a
    percentage. For every x: part in the final formula there are :x parts
    for it to be added to. And a ratio in the spoken language is
    pronounced- to. So 1:3 is pronounced and meant to be 1 part of
    something added "to" 3 parts of something else. It turns out to be a
    25% dilution but that is secondary to what the ratio is. Not ambiguous
    at all. Pretty simple. James
     
  10. Mathematically 1:3 is a ratio, which usually associated with
    mulitplication or division, to interpret 1:3 as 1+3 is incorrect.

    <p> 1:3 = 2:6 =3:9 = 0.33333

    <p> To interpret "a RATIO of 1 to 3" as "1 plus 3" is clearly
    incorrect.

    Because 1:3 =2:6 =0.33333 never = 1+4

    <p> I much prefer the usage dilute 1 part stock + 3 part water
     
  11. Further, according to the Oxford Dictionary of English,

    the word dilution means a degree of dilute. Given as example"
    " An antidote was administered at dilution 1:50"

    My understanding is, in English usage, a dilution of 1:50 means

    the concentration of the final solution is only 1:50 or 1/50 of
    the original.
    <p> Further, 1 ml of the dilution, has a strength of only 1/50
    of the original antidote.

    <p> From liguistic standpoint, the correct interpretation of
    "dilute 1:3" is dilute to a RATIO OF 1:3
    Not dilute to 1+3.





    <p>
     
  12. The following is a definition of dilution

    <p>

    "Dilution : The effect of changing the concentration of a solution by
    the addition of more solvent.
    A dilution of 1:10 means the addition of 9 volumes of the solvent to
    1 volume of the original solution.
    The resulting solution is one tenth as concentrated as the original."

    <p>


    Taken from:

    <p>

    http://www.nico2000.net/DataSheets/glossary.html
     
  13. If 1:3 means mix only on part stock to 2 parts water to make a final
    mix, then what would 1:1 mean?
     
  14. What is USD to CD$ at 1: 1.5 ? Us dollar = 1+1.5 =2.5 Canadia
    $.

    What is a map of 1:100,000 ? 1+100,000 ? absurd !
    <p> To interpret 1:N as 1+N is out right wrong !





    <p>The subject title of my question is "Subject: The ambigity
    of "dilution 1:3"

    <p> All I need to to is to find ONE definition, I have suceeded.
    It IS ambiguous !
     
  15. In dilution, there are THRREE volumes, A the orginal concentrate,
    B the volume of solvent, C the final volume

    <p>

    In dilute 1:3 only TWO volumes are specified, 1, and 3
    one of these two must be the original stock, not necessary 1


    <p>

    Dilute 1:3, UNSPECIFIED, has three possible meanings

    <p>

    1 part stock add solvent to make 3 part final

    1 part of stock + 3 part of water

    <p>

    1 part of water + 3 part of stock
     
  16. Dan, what is macro 1:1 means ?

    <p>

    Meticulous technical instructions all avoid "dilute 1:3"

    <p>

    They specified clearly 1 part CONCENTRATE + 3 part water

    <p>

    You never see Ilford or Kodak use "dilute 1:3" style sloppy,
    instruction on their bottles.
     
  17. Is this a question or a lecture?
     
  18. Martin Tai is quite correct. Photographers have been using incorrect
    notation for 50 years or more. Not that it matters all that much, so
    long as we all know what we mean. Richard Henry explains this in his
    book "Controls in Black and White Photography".

    <p>

    I don't want to hear any more smart-ass comments about people whose
    native language is not English. That message and any like it will be
    deleted.
     
  19. Comments about non-native speakers of the English language are
    not "smart-ass". Usage of language is based on generally accepted
    and contextual meaning, not necessarily the literal or out-of-context
    rules established in a dictionary that has a reputation for not being
    current on legitimate "popular usage". If photographers have been
    using this notation for 50 years, then it is about time the Oxford
    dictionary is changed (with respect to the usage of dilution in
    photography). Like you say, everyone knows what is meant, and
    therefore the entire subject is nothing more than beating a dead
    horse.
     
  20. Martin said: "But when it comes to serious instruction, Kodak has
    being very precise, for example on Tmax developer bottle " Add one
    part concentrate to 4 part water ", they don't say dilute 1:4."

    <p>

    That is not entirely accurate. In accordance with the generally
    accepted PHOTOGRAPHIC use of the term dilution, Kodak uses 1:3 to
    mean that 1 part solution is mixed with 3 parts water. They clarify
    it the chart heading, but Kodak does use the generally accepted
    photographic notation. See the web site:
    http://www.kodak.com/global/en/professional/support/techPubs/e103cf/e1
    03cf.pdf
     
  21. In the post immediately above, the last part of the web reference did
    not post correctly. it should be: e103cf.pdf
     
  22. THAT,S why I only use 1:1 dilution! Cheers CC
     
  23. 1:28, 1:29, 1:30 OR 1:49, 1:50, 1:51... (my most common dilutions)
    Startling different results, I don't think so! I can't measure it
    accurate enough to tell you what the end result was. The end result
    is what matters and I'm happy with that.
     
  24. Although I do not agree with Martin Tai's argument 100%, as far as I
    can tell his main problem is the notation and is separate from
    someone's measurement accuracy and insignificance of the difference it
    makes in resulting image quality.
     
  25. "A relationship between the amounts or sizes of two things, expressed
    as a quotient: proportion." It is not 1 "in" 3 but 1 "to" 3. One part
    stock solution "to" three parts water. Pretty clear. James
     
  26. I have been always using 1:3 ratio to simply represent dilute 1 part in 3 parts water to give a final volume of 4X dilution factor.
     
  27. Martin Tai and Ed Buffaloe are correct: the convention used by photographers differs from real-world laboratory practice. If you want to be clear, state it as a percentage, like "50% Xtol" or "HC-110 3%".
     
  28. Actually, to be pedantic, ":" doesn't mean "ratio"; "/" does. i.e., 1/3 means one part in 3. Mathematics does not use the colon to denote ratios; it uses the slash. Ratios are division.
     
  29. This is why chemists use molarity - then there is no ambiguity.
     

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