Commentary, long, ignore
Commentary, long, ignore
This is the most poorly written data I have ever seen.
It is pretty confusing. You only need to look at all the arguments about whether dilution information means 1+dilution or 1:dilution ratiometrically (it is the former, not the latter, by the way) to see that Kodak's data sheets are fairly easily confused.
In practice there are always 2 limits - adequate chemicals to develop all the exposed silver (not much) and enough chemistry to develop the exposed silver sufficiently evenly to avoid weird development marks on the film (a lot more).
The only exception I know is Xtol, and no-one (including one of the designers of Xtol) had been able to explain to me why this is so.
Sort-of, with regard to Xtol. In Xtol the ascorbate develops silver with similar efficacy as hydroquinone, regenerates the dimezone-S (secondary developing agent) and also acts as a preservative like sulfite. What you can be sure of is that Xtol dies because the ascorbate is doing a lot of different things and it is exhausted in solution relatively easily and quickly. What is very unclear is exactly how all the different ascorbate functions interact, but sometimes observational data beats a basis of theoretical understanding.
The trend for using Rodinal in homeopathic concentrations also shows that a minimum amount is needed fairly well too. Look around the web at all the blotchy scans from 'high dilution' Rodinal done badly. In this case the other, concomitant trend for stand development makes this worse and it can be hard to differentiate dilution blotch from stand blotch.
The amount of developer you need to develop a film is tiny. If you doubt me, consider the following two examples.
1 Polaroids. Two teaspoons of chemicals suffice to develop and fix a piece of film that is maybe 20% of the area of a 36-exposure 35mm film.
To be fair, polaroid film used two teaspoons of concentrated paste.
2 Two-bath developers. ALL the developing agent is normally in the first bath, so you're developing it with what soaks into the emulsion: again, a couple of teaspoons' worth. The second bath merely provides a nice, wet alkaline environment to let the developer work.
Except there is almost always enough sulphite or other alkaline product in divided developers for the A bath to do quite a bit of developing. I've fixed films straight out of the A bath to test this. It makes sense: 3-4 minutes in the equivalent of stock D76 or HC110 dilution B is enough to mostly develop many films, especially the old technology films that work well in divided developers.
The vast majority of the developer that you pour into the tank is there merely to ensure that the film is wetted rapidly and evenly. If it's very weak it may by the end of the development time have oxidized into uselessness, or been poisoned into uselessness by developer by-products (notably hydrobromic acid), but really, you don't need to worry about developer volumes.
This is true, absolutely, but consistency and evenness also come from being able to replace locally exhausted developer quickly. It's one of the reasons I prefer to use time to control contrast rather than modifying agitation.
This isn't just me making it up: it comes from quite long discussions with people who know a great deal more about the subject than I do, and from reading serious books such as those by L.P. Clerc, Grant Haist, C.B. Neblette and Pierre Glafkides. Google their names if you're not familiar with their work.
This is, of course, true, but somewhat academic. Development occurs on and in the film, and what is elsewhere in the tank is largely an innocent bystander (particularly without agitation), but assuming that molecule A in the developer will find molecule B in the film irrespective of where it is in the solution ignores the realities of the physical situation in a 1L developing tank.
Although I happen to be using Ilford DD-X at the moment, for many years my standard for developing 35mm film in D-76 1+1 has been three rolls of film at a time in 40 oz of D-76 1+1 in a 5-reel Paterson tank.
This is similar to what I do with D76. It works out to (rounded off) 150mL stock/roll. Kodak's times are for 240mL of stock/roll, and they say to extend the time by 10% if using 120mL stock/roll at 1+1. I’ve found this accurate, which suggests that this amount of stock/roll is starting to exhaust. I find that more stock provides better consistency.
Here is a practical test: try developing 4 films in 1L of D76 1+3 (62.5 mL stock/roll). The photos are very likely to come out blotchy. Even if you use constant agitation, it doesn’t work very well. Then try 2 rolls in the same situation (125 mL stock/roll). It works much better.
Marty
