Help w/ dilution ratios for a newbie

[Steve Smith]

1:4 means one part + three parts making a total of 4 aprts, so 1:20 means 1+19.

Whilst this is technically true, and is the way chemists use it, it fails when a dilution of 1:1 is given!


Steve.

 

[AgX]

Whilst this is technically true, and is the way chemists use it, it fails when a dilution of 1:1 is given!

That would be an exception.

As I pointed out when speaking of a "dilution of" likely the final solution is referred to.
But as "1:1" typically is not used to describe a solution (but rather "100%" is used), in this case I would read "a dilution of 1:1" as "1+1". But only in this case.

For the rest see post #23 .

 

[AgX]

With paper developer... When developing film [these concentrations] do matter.

What I meant was that with 1:3/1+3 the situation is different than with 1:20/1+20 concerning the effect of deviatian. Often we have got strong dilutions.

 

[Tony-S]

Whilst this is technically true, and is the way chemists use it, it fails when a dilution of 1:1 is given!

No, it doesn't. 1:1 is undiluted (straight developer) with no water added. The math is:

1:10 = 10-1 = 9 parts water
1:3 = 3-1 = 2 parts water
1:1 = 1-1 = 0 parts water (i.e., undiluted)

 

[Peter Schrager]

1:1is NOT UNDILUTED...1 part developer and 1 part water
1:3....1part solution..3 parts watee
1:2...1 part solution to 2 parts water

 

[darkroommike]

No.
1:4 means: one fourth of the final solution

1+4 means: add 1 part to 4 parts

Though sometimes people writing instructions do not get that right themselves.

So if I need 16 oz. of D:76 1:1 I start with 16 oz of D-76 to get a total volume of 16 ounces.

This has been discussed here and elsewhere many years, 1:4 is not a fraction it is a ratio. And reads 1 PART A and 4 PARTS B or 1 to 4

I'll add with an edit:

Ilford ID-11 1+1 is equivalent to Kodak D-76 1:1 the first is read one part stock plus one part water the second is read as one part stock TO one part water.

Now figure out a three part developer 1:1:10:100 dilution...

 

[AgX]

This has been discussed here and elsewhere many years, 1:4 is not a fraction it is a ratio. And reads 1 PART A and 4 PARTS B or 1 to 4

Discussing things over many years does not make things true.


The fact that there are discussions is a sign for ambiguity of the subject.

(I only can refer for the 2nd time to post #23)

 

[Tony-S]

So if I need 16 oz. of D:76 1:1 I start with 16 oz of D-76 to get a total volume of 16 ounces.

This has been discussed here and elsewhere many years, 1:4 is not a fraction it is a ratio. And reads 1 PART A and 4 PARTS B or 1 to 4

I'll add with an edit:

Ilford ID-11 1+1 is equivalent to Kodak D-76 1:1 the first is read one part stock plus one part water the second is read as one part stock TO one part water.

This is precisely why we have this discussions; Kodak screwed the pooch, so to speak, when they used this nomenclature. The use of the colon is used differently by those of us in the sciences. A 1:10 dilution is also a 10^-1 dilution. Had Kodak used the same nomenclature as Ilford, for example, then we wouldn't be having this discussion because the use of a plus is unequivocal.

Now figure out a three part developer 1:1:10:100 dilution...

100-1 = 99
99-1 = 98
98-10 = 88

88 parts water, plus 1 part of each of the first two and 10 parts of the third.

 

[Tony-S]

1:1is NOT UNDILUTED...1 part developer and 1 part water
1:3....1part solution..3 parts watee
1:2...1 part solution to 2 parts water

In chemistry and biology it is. This is why Kodak has caused so many problems - their unconventional use of the colon.

 

[Sirius Glass]

1:1is NOT UNDILUTED...1 part developer and 1 part water
1:3....1part solution..3 parts watee
1:2...1 part solution to 2 parts water

He got it right. Those that could not pass elementary math and basic algebra will disagree but they still will be wrong no matter how many times they post their illogical rants.

 

[silveror0]

Take a look at Kodak's table of dilutions for HC-110 concentrate (Dilution B is a very common dilution) that states very clearly the their use of the colon means the RATIO of water volume added to concentrate volume:

https://web.archive.org/web/2015021.../en/professional/support/techPubs/j24/j24.pdf

1 fl.oz. of concentrate + 31 fl.oz. water yields 32 fl.oz. (1 qt. of working solution) and is defined as a 1:31 dilution. Therefore 1:31 is the same as 1+31. I recently queried Steve Anchell about this and he concurred that the colon is synonymous with the 'plus' and that the colon is simply the earlier designation style of the two.

 

[jgcull]

Goodness, it's been clear to me for years till I began reading all the answers. ;o)

 

[Arklatexian]

Well since some think that A:B means A/[A+B] we should rewrite all books on photography and chemistry to satisfy them, but first we will have to reinvent mathematics starting with the number system and algebra and moving upwards to correct their mislearning the ratio concept back in the seventh grade. Dagnabit now where did that righteous weed go?

Sirius Glass, I too was taught that the two dots between the numbers represented a "ratio". In this post, have you noticed that most of the arguments against using ratios have come from Europeans (Brits and Germans)? Maybe where they were taught Algebra, they used some different terms than we were taught on this side of the Atlantic. In any case, I consider ":" a form of shorthand, Am I correct?.........Regards!

 

[Sirius Glass]

Sirius Glass, I too was taught that the two dots between the numbers represented a "ratio". In this post, have you noticed that most of the arguments against using ratios have come from Europeans (Brits and Germans)? Maybe where they were taught Algebra, they used some different terms than we were taught on this side of the Atlantic. In any case, I consider ":" a form of shorthand, Am I correct?.........Regards!

You are correct. The mathematical definitions have not changed since we when to school. Not even in the Eastern Hemisphere.

 

[Leigh B]

I don't think anyone questions the fact that ":" signifies a ratio.

The entire argument is "a ratio of what to what"?

It can be a ratio of one component to another, or of one component to the whole.

- Leigh

 

[Sirius Glass]

And that is the fly in the ointment. If one is going to use the ratio of A to [A+B], then one needs to either state that or expand at say one unit to nineteen units. The responsibility is on the manufacturer to clearly write out the instructions. Since one must RTFM, the manufacturer needs to write TFM in an understandable and clear way.

 

[MattKing]

Since one must RTFM, the manufacturer needs to write TFM in an understandable and clear way.

Which in almost every case* Kodak does. The problem arises when people just look at the shorthand, without paying attention to the clear explanation/definition of the shorthand.

*The exceptions most likely arising from revisions over the years - Ian's reference to selenium toner being an example.

 

[Leigh B]

Since one must RTFM, the manufacturer needs to write TFM in an understandable and clear way.

If TFM was clear and understandable, F would take on a whole new meaning, incomprehensible to most.

- Leigh

 

[AgX]

Take a look at Kodak's table of dilutions for HC-110 concentrate (Dilution B is a very common dilution) that states very clearly the their use of the colon means the RATIO of water volume added to concentrate volume.

Nobody doubts this.
The issue is what a user makes out of the meaning of that division sign when he does not have that text or is unsure if this Kodak way of writing applies in that very case too (not all manuals are written by the same person) or when it is not even a Kodak manual and when the actual text is ambiguous too.

 

[Tony-S]

Which in almost every case* Kodak does. The problem arises when people just look at the shorthand, without paying attention to the clear explanation/definition of the shorthand.

I don't think that reading off of Kodak's label is as much a problem as when people have questions about the use of developers. Because the colon is ambiguous, you cannot be sure; whereas the plus is unambiguous. The colon can lead to confusion, mistakes and frustration from bad results. Here's an example of a thread on developing Pan F+ from several years ago.

(there was a url link here which no longer exists)

I also use an RB67 and my usual combination is Pan F @ iso 16-20 and Perceptol 1:2 22 degs for around 11 mins. I stress again though, I've not arrived at these figures from exhaustive testing, It's just what works for me and my particular style.

Hi Bill and thank you for contributing to this discussion and for your clear explanation for film exposure and developing time.

Q1; Is 1:2 the same as 1+2?

 

[Sirius Glass]

Now that everyone uses the internet, anyone can look up the meaning of ':' as it relates to photo chemistry, if they are confused or have a question. They can also ask on internet if they want a wrong answer.

 

[Tony-S]

Now that everyone uses the internet, anyone can look up the meaning of ':' as it relates to photo chemistry, if they are confused or have a question. They can also ask on internet if they want a wrong answer.

Yeah, because we wouldn't want to use standardized nomenclature with unambiguous meaning.

 

[Will sameb]

I just wanted to thank everyone for their thoughtful replies.
(And, to apologize for accidentally stirring this up.)

 

[Sirius Glass]

I just wanted to thank everyone for their thoughtful replies.
(And, to apologize for accidentally stirring this up.)

Think nothing of it. We need to be stirred up every once is a while or we will drop out of solution and form a sludge.

 

[MattKing]

I just wanted to thank everyone for their thoughtful replies.
(And, to apologize for accidentally stirring this up.)

No apology is necessary.
The fact that you wanted clarification is indicative of the fact that there is potential confusion for you and others. If all anyone takes from this is the lesson that there are differences in how these things are expressed, and it is important to carefully read the full instructions, then the thread is definitely worthwhile.