When making comparisons it's often necessary to alter the actual concentration to compare two developers it's the ratio's of p-Aminophenol to Sulphite that are important. The early BJP Almanacs had no final volume for their p-Aminophenol developer, it's still not listed in the the 1920's.
A problem is that 300gms of Metabisulphite, a litre of boiling hot Water, 100gms of p-Aminophenol then Hydroxide solution will have a final volume well in excess of 1 litre. Water is releaseded as well when the Hydroxidee reacts with Metabisulphite to form Sulphite. That's why I said "No final volume of solution is given but it's likely to be 2 litres if you want the equivalent of early Rodinal."
It's convention with formulae to make up to a litre with water, so while the BJP doesn't say that specifically for other formulae they publish the same formulae published by a company like Ilford or Kodak etc would. Ilford (pre WWII) said Water up to 1 litre, Kodak Water to make 1 litre.
Only ~24.3 mLs of H2O is released from 300g of Potassium Metabisulphite from that reaction, it is inconsequential.
Even in solution, all these things will have densities far greater than 1.0 g/cm^3, not less, so it certainly wouldn't be 2 litres. All the formulae in the almanacs are given to be used as they are, they are based around starting with 1 litre of water, not making a final volume of 1 litre or x litres, all the formulae are given. Whatever it comes out to be is the final volume without adjustment of extra water, all the formulae in the almanac are given this way and are intended to be used that way. That is the convention in the almanac. What Ilford and Kodak did is a different convention. I wouldn't confuse the two.
To elaborate, their convention is to specify concentration by weight to volume in 1 litre of solvent (water), not 1 litre of final volume, which is less than 1 litre of water.
IE, it's 100g amidophenol, 300g of metabisulphite in 1 litre of water not 1 litre of volume. To which potash is added.
edit: Upon further reading, the volume of water created should be less, it appears the 300g of metabisulphite specified is intended to not be the anhydrous form.
Last edited by Athiril; 09-17-2011 at 06:02 AM. Click to view previous post history.
I said dilution to 2 litres to be the equivalent of early Rodinal, that gives the same in concentration of stock solution, so you're being a bit pedantic here .
It's always been the convention to make up to the final volume and the BJP is as vague as making this clear in all formulae as many other publications. My point about Ilford & Kodak formulae is that the BJP often published them with out specifically stating that they should be made up to a specific volume while the companies did in their own publications. That goes back to at least the 1890's the BJP doesn't use a different convention.
The instruction in the book is to use all the formulae as is provided.
I disagree with what you have said about the book, it isn't vague, people are interpreting it incorrectly from what I can see of it so far.
It is quite specific, not vague.
It will read;
Water... 1,000 c.c.s.
As in many formulae, with direction for usage.
Other formulae in the book will read;
Water to... 1,000 c.c.s.
It hasn't been omitted from what I can tell, but designed that way on purpose, as the density is likely to change, and is consistent this way. So as before, it's stating x in 1 litre as opposed to x as part of 1 litre.
When the formula calls for as part of, the book specifies it.
If it were intended to be 2 litres, it would say water to. It doesn't. It is not the only formula like that in there.
Density and solubilities will change especially with cooling in that formula. It's only logical it'd be designed to be completed at the indicated temperature. Watering it to 2 litres will give you a different volume when it cools, adding different temperature water would suddenly precipitate stuff too I would think.
Adding extra water at the cold stage would mean that the final solution isn't as close to saturation and less of a concentrate design which it is intended to be.
In fact under the two solution version of "Paramidophenol", it specifies "distiller water to".
If that's not enough the Pyro-Caustic Soda (Valenta) formula calls for "water to" in part A, and simply "water" for part B.
Last edited by Athiril; 09-17-2011 at 07:48 AM. Click to view previous post history.
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I'm interested in trying Rodinal. Given the range of versions and the changes that occur from time to time in various markets, I'm attracted to EZ-Rodinal. To those who have made careful comparison of the variants can I ask:
Originally Posted by georg16nik
Once dilutions and development times are adjusted by testing, is there any discernible difference between them, particularly in effective film speed?