Consensus on the notation of dilutions

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• 05-19-2012, 06:47 PM
Diapositivo
"Ratio" in English has two meanings, which in Italian can be rendered as "rapporto" in one case, and "proporzione", which I think is translated exactly by the English word "proportion".

The first case, rapporto, or quoziente, is expressed with / or something to that effect.

If I say that 4/5 of APUG forum participants do not write in proper unambiguous English ;) the second member, the divisor, is the "total"* of the two groups of APUG participants, and the first, the dividend, is those for each five participants who cannot use unambiguous English.

If I say that the proportion between those who can use unambiguous English and those who cannot is 1:4, I say the same thing expressed as a proportion.

Those two kinds of notation, 1:4 and 1/5 or 4:1 and 4/5 are, if I get it right, both termed "ratio" in English.

This is made worse by the fact that / and : are alternative signs for "division", and although it is customary to use / for "rapporto" and : for "proportion" this subtleties can go lost for writers of instruction booklets.

A trained person always reads 1:10 as "one to ten" (eleven parts in total) but many would read it as 1/10. It would be called a "ratio" in both cases correctly but the dilution would be different.

I guess in Italian and in other languages the ambiguity would be resolved because it would be specified "a proportion of 3:10" or "un quoziente di 3/13". In English you are pretty much stack with "ratio" which is "irrational" a way to express oneself ;) (quotient, proportion should find larger use).

Fabrizio

* OK it's not the "total" you get what I mean...
• 05-19-2012, 07:02 PM
Photo Engineer
Fabrizio;

The ":" is never used alone for division. It is formed from a dash through the colon (terrible double meaning here! :D ). The notation 1/10 is still one tenth which is 10% or 1 + 9 or 1:9. More a function of math than English I think.

PE
• 05-19-2012, 07:29 PM
jnanian
1: 9 1+ 9
its the same as saying
salt and paper
or salt n'peppa

"whatever it is" : or + ( added to ) " whatever it is"

the worst is when it is 1:9:1 and there are only 2 things being mixed !
• 05-19-2012, 07:42 PM
Photo Engineer
Just as a side note, from way back when....

Back at the origin of chemistry and photography, things were expressed in parts such as:

7 parts Metol
3 parts HQ
0.5 parts KBr
25 parts Sodium Carbonate
and 1000 parts water

Regardless of the measurement units used, Grams, Ounces, Millifarkles or whatever, the ratios always came out right using YOUR units. And, they made up molal solutions not molar. So, that is the origin of many of our formulas and procedures. Everything was assumed to be in ratios or parts, not the native measures.

So, if parts were grams you have:

7 grams Metol
3 grams HQ
0.5 grams KBr
25 grams Sodium Carbonate
1000 grams of water

This way you can read very old formulas and come up with something workable.

PE
• 05-19-2012, 09:23 PM
ic-racer
The title of this thread is an oxymoron.
The discussion of the topic is both futile and moot.

For example Kodak publication j86 on T-max developers does not use either notation! It state the dilution as follows:

Quote:

You can easily mix smaller volumes by mixing one
part of the concentrate with four parts water.
• 05-19-2012, 11:51 PM
Photo Engineer
Kodak uses similar notation for Dektol. :D

PE
• 05-20-2012, 01:23 AM
Craig Swensson
Okaaay, so what is the answer to the OP:D
• 05-20-2012, 02:30 AM
Steve Smith
Quote:

Originally Posted by Vaughn
I have always thought of it as ratios, with 1:31 yielding 32 parts

So have I but not everyone agrees with us!

Steve.
• 05-20-2012, 05:28 AM
Jüri
I don't see why should we use 2 symbols for the same thing and limit ourselves with the "ratio" meaning.

For me 1:10 is 1 part of total of 10 parts. 1+10 is 1 part plus 10 parts. Simple.
• 05-20-2012, 06:49 AM
Steve Smith
Quote:

Originally Posted by Jüri
For me 1:10 is 1 part of total of 10 parts. 1+10 is 1 part plus 10 parts. Simple.

Not always simple though.

Sometimes you see "dilute 1:1 with water". Does that mean you don't add any water?!!

To me it means a ratio of one part developer (or whatever) to one part water.

Steve.
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