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.

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

IMO, the usage in some photography writing ( dilute 1:3 as add 3 part water to 1 part stock ) is incorrect

-- martin tai (cg01@torfree.net), July 16, 2001

Answers

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.

-- N Dhananjay (ndhanu@umich.edu), July 16, 2001.

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.

-- r (ricardospanks1@yahoo.com), July 16, 2001.

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.

-- Pete Andrews (p.l.andrews@bham.ac.uk), July 16, 2001.

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.

-- Tim Brown (brownt@flash.net), July 16, 2001.

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

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

Ilford instructon is also precise, they say " 1 part concentrate + x part water "

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.

Dilution 1:3 indicate a degree of thiness. (See New Oxford Dictionary of English )

Agfa also say " add one part concenrate to 15 part of water"

So IMo, dilute 1+3(water ) is better than dilute 1:3

The most strict difintion must be the one followed by chemists and pharmacists: dilute 1 part (of A )with solvent to make 3 parts

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.

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.

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.

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.

Fortunately, in photography dilution mostly refers to acqueos solution, and 1+ 3 = 4 parts.

-- martin tai (martin.tai@capcanada.com), July 16, 2001.

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.

-- william nagel (wdnagel@home.com), July 16, 2001.

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.

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.

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.

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).

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.

-- Ryuji Suzuki (rsuzuki@rs.cncdsl.com), July 16, 2001.

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

-- james (james_mickelson@hotmail.com), July 16, 2001.

Mathematically 1:3 is a ratio, which usually associated with mulitplication or division, to interpret 1:3 as 1+3 is incorrect.

1:3 = 2:6 =3:9 = 0.33333

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

I much prefer the usage dilute 1 part stock + 3 part water

-- martin tai (martin.tai@capcanada.com), July 16, 2001.

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.

Further, 1 ml of the dilution, has a strength of only 1/50 of the original antidote.

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

-- martin tai (martin.tai@capcanada.com), July 16, 2001.

The following is a definition of dilution

"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."

Taken from:

http://www.nico2000.net/DataSheets/glossary.html

-- martin tai (martin.tai@capcanada.com), July 16, 2001.

If 1:3 means mix only on part stock to 2 parts water to make a final mix, then what would 1:1 mean?

-- Dan Smith (shooter@brigham.net), July 16, 2001.

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 !

To interpret 1:N as 1+N is out right wrong !

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

All I need to to is to find ONE definition, I have suceeded. It IS ambiguous !

-- martin tai (martin.tai@capcanada.com), July 17, 2001.

In dilution, there are THRREE volumes, A the orginal concentrate, B the volume of solvent, C the final volume

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

Dilute 1:3, UNSPECIFIED, has three possible meanings

1 part stock add solvent to make 3 part final 1 part of stock + 3 part of water

1 part of water + 3 part of stock

-- martin tai (martin.tai@capcanada.com), July 17, 2001.

Dan, what is macro 1:1 means ?

Meticulous technical instructions all avoid "dilute 1:3"

They specified clearly 1 part CONCENTRATE + 3 part water

You never see Ilford or Kodak use "dilute 1:3" style sloppy, instruction on their bottles.

-- martin tai (martin.tai@capcanada.com), July 17, 2001.

Is this a question or a lecture?

-- Nigel Smith (nlandgl@unite.com.au), July 17, 2001.

Neither.

-- Ryuji Suzuki (rsuzuki@rs.cncdsl.com), July 17, 2001.

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".

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.

-- Ed Buffaloe (edb@unblinkingeye.com), July 17, 2001.

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.

-- Michael Feldman (mfeldman@qwest.net), July 17, 2001.

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."

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

-- Michael Feldman (mfeldman@qwest.net), July 17, 2001.

In the post immediately above, the last part of the web reference did not post correctly. it should be: e103cf.pdf

-- Michael Feldman (mfeldman@qwest.net), July 17, 2001.

THAT,S why I only use 1:1 dilution! Cheers CC

-- Carl Crosby (humminboid@aol.com), July 17, 2001.

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.

-- Nigel Smith (nlandgl@unite.com.au), July 17, 2001.

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.

-- Ryuji Suzuki (rsuzuki@rs.cncdsl.com), July 18, 2001.

"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

-- james (james_mickelson@hotmail.com), July 22, 2001.