Dumbest Question

RIchardn · Jul 21, 2006

This is porbably the dumbest question to be posted but here goes:-

when the Massive Dev Chart says, for example Rodinal 1+100 does it mean 600ml of water + 6 Ml of Rodinal or 600 ml containig 6 ml Rodinal?

david b · Jul 21, 2006

hey richard. that is not a dumb question, as I once posted the same thing.

I was told that it really did not matter at this volume because of the small amount of rodinal. A difference of 6ml of water is not a big deal.

When I do my APX 100 or Pan F+ in rodinal 1+100, it is usually in a 1000ml tank where I do 1000ml water and 10ml rodinal.

No matter how you do it, I do not think you will see any difference.

Konical · Jul 21, 2006

Good Morning, Richard,

To me, it means 600 water plus 6 Rodinal, but with that much dilution, a few milliliters one way or the other probably would have minimal effect.

Konical

Claire Senft · Jul 21, 2006

From a practical standpoint one can easily measure out 6 ml of Rodinal with a pipette or syringe. How would you measure out 594 ml of water?

If you wish to bea fussy about reducing variation and you have a scale that allows you to do so, you could weigh out your water...but I doubt that the difference is worth the effort even for the terminally fussy.

Gerald Koch · Jul 21, 2006

At least the Massive Dev Chart uses a '+' sign rather than the truly ambiguous ':' in representing dilutions.

Gerald Koch · Jul 21, 2006

As has been said "There are no dumb questions only dumb answers".

Travis Nunn · Jul 21, 2006

Gerald Koch said:
At least the Massive Dev Chart uses a '+' sign rather than the truly ambiguous ':' in representing dilutions.

Funny. I've always thought the ' : ' was clearer than ' + ' sign. I guess its all what you're used to.

Wigwam Jones · Jul 21, 2006

I have often wondered about this myself. A ratio is generally expressed as 1:100, not 1+100, but they are quite often used interchangeably when one speaks of developers. Are they the same? Semantically, I would suspect that 1+100 means literally 1 part developer and 100 part water, or a volume of 606ml in your example.

Dilution, on the other hand, can be figured this way:

"aliquot" is the developer in this description.
"diluent" is the water in this description.

"dilution factor" is the ratio you are trying to understand, expressed as 1:100 in our terms.

To prepare a 600ml solution at a dilution factor of 1:100, the math would look like this:

1) Find out how much aliquot you need: 600ml / 100 = 6ml
2) Subtract the aliquot from the total volume you want: 600ml - 6ml = 594ml
3) Fill your container with 594ml of water and 6ml of Rodinal.

You now have a 1:100 dilution.

Is this the same as 1+100? No, but as others have said, at that dilution, the difference may well be covered by minor changes in development such as time, temperature, or agitation, even if it would be appreciable otherwise.

I have noted in several places that Agfa generally expressed their dilutions as x parts plus y parts (x+y) rather than as a ratio (x:y). I don't know why.

RIchardn · Jul 21, 2006

Thanks everyone for your help I am used to using acutol at a ratio of 1:9 ie I measure 60 ml of acutol and put in larger measuring cylinder topping up to 600ml with water.
A has been said it is a matter of being clear about the difference between + and :

Cheers
Richard

erikg · Jul 21, 2006

Claire Senft said:
From a practical standpoint one can easily measure out 6 ml of Rodinal with a pipette or syringe. How would you measure out 594 ml of water?

Well, you don't have to measure out the water. Just start with 500 ml water, add your 6 ml Rodinal and then bring the total volume up to 600.

It does not matter either way, But I think the main thing is to do it the same way everytime, It just becomes part of your personal system.

Wigwam Jones · Jul 21, 2006

erikg said:
Well, you don't have to measure out the water. Just start with 500 ml water, add your 6 ml Rodinal and then bring the total volume up to 600.

It does not matter either way, But I think the main thing is to do it the same way everytime, It just becomes part of your personal system.

Or you can remove 6ml of water from 600ml, and then add the 6ml of developer. But I agree, in the end, at high dilutions like this, the difference is probably insignificant.

Ole · Jul 21, 2006

But there's a lot of difference between 1+2 and 1:2 dilutions, so it pays to be unambiguous.

JBrunner · Jul 21, 2006

Since all schemes with developers- dilutions-times-agitations, etc. are basically "serving suggestions" I don't think it matters one bit. What does matter is being consistent, and avoid random results, that offer no feedback on your developing regimen.

Ole's point is well taken, however.

srs5694 · Jul 21, 2006

Others have posted good information, but I'll just add a couple of points. First, concerning the 1+100 vs. 1:100 notation, I recall seeing a lengthy post about this in which scientists from different fields disagreed over which was the correct notation, given the way they're used in photography. As somebody from outside those fields, my conclusion is therefore that both notations are correct, depending on your field of study or perhaps where you studied.

Second, at lower dilutions, the difference in interpretation is important. If you have trouble remembering what it means, think of a 1+1 (or 1:1 if you prefer) dilution. That's different from using undiluted developer, so 1+1 cannot mean one part developer per part of final working solution; it must mean one part undiluted developer plus one part water.

ZorkiKat · Jul 23, 2006

The ORWO FORMULAE book used the "+" notation for dilution instructions. I always thought (and used) that "1+100" meant 1 part plus 100 parts or total of 101. In this ORWO book, for instance, a 1+40 R09 dilution means that 1 part R 09 (rodinal) should be used with 40 parts water.

For example, to make a 400ml working solution of 1+40 R09, the total volume (400 ml) is divided by 41 (1+40), and the dividend (almost 9,8ml) would represent the amount of concentrate needed. Then water to make 400 ml is added.

In the end, I don't think it really matter whether 9.5 or 10 ml is used- as what would happen if 1 part concentrate was added to 40 parts water- the resulting volume in the given example would no longer be 400 ml but 410 ml.

Jay

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