Thank you for summarising the benefits of 2 baths developers, however, your last point "increased risk of non-uniformity with roll films" confused me. I thought, from my readings on the subject, that 2 baths developers are meant to be used with non-uniformly exposed negatives!
Thank you for summarising the benefits of 2 baths developers, however, your last point "increased risk of non-uniformity with roll films" confused me. I thought, from my readings on the subject, that 2 baths developers are meant to be used with non-uniformly exposed negatives!
I'm not sure that the argument, "I don't want to complicate things and have another bottle to store, etc," is such a compelling argument against two-baths. How much of this really represents, "I like how I am doing things and don't want to change."
The needs of a beginner can be different than those of an expert user. The need to avoid failures and the disappointment they bring is more important for a beginner, and divided developers can be more forgiving. Beginners may be trying out different types of film for the first time, and divided developers can accommodate that.
By uniformity I mean evenness of development. There is generally going to be more risk of uneven development with two bath development relative to a properly formulated single bath developer. It might take some experimentation to find the best / most consistent method.
The image characteristics are baked into the film and your development technique has a limited effect on the result.
Thank you for summarising the benefits of 2 baths developers, however, your last point "increased risk of non-uniformity with roll films" confused me. I thought, from my readings on the subject, that 2 baths developers are meant to be used with non-uniformly exposed negatives!
Why is that?
I'm not the OP, but I'm a bit confused. Are you referring to uneven development from one shot to the next, or uneven development within the same image?
2 bath developers are NOT temperature independent. You can vary the temperature of the two baths somewhat, but if you work at 85F (or 60F) then you are most definitely going to change the results. Many two part (divided) developers use a Bath A that is a functional developer on its own. For example, Barry Thornton's version of Divided D-23 has a Bath A that is nearly identical to regular D-23 and it acts as a rather slow developer, without the use of Bath B. So if you are using a divided developer of this type and you deviate significantly from 68F, you're going to have an effect on the outcome.
I've found that 2 bath developers rarely deliver full emulsion speed. I prefer Thornton's version myself, but it always requires 1/2 to 1 full stop more exposure to get negatives I want. Karl Matthias's "2B-1" is better at enhancing film speed, sometimes giving an extra half stop of speed, depending on the film you choose.
Divided developers aren't more popular because they require making from scratch from chemicals that not everyone cares to acquire and keep in their darkroom (takes up space, tedious to weigh out and assemble). It also adds another step in the process, and many people barely have the patience for standard "develop/stop/fix" protocols, let alone adding another step.
Because before most of us were born, Eastman Kodak Company spent more money than most countries' GDP on R&D to market the finest and most consistent quality products the world ever has known or ever will. All you needed was a bottle, some clean water, a thermometer, and follow the instructions as they wrote them. Tiny nuanced results from other products and experiments can't top that to any remarkable degree.
What I have read and heard till now that 2 bath b&w negative developers have many advantages over conventional single bath ones. Like, they are temparature and film independent, very good for highligh control, usually maintain and sometimes increase film speed, keep for long time etc.
My question is, if 2 bath developers are so good, then why do we use conventional single bath developers at all?
The whole deal with 2 bath for the purposes of use on unknown films or getting the most from shadow details, is simply taking advantage of the fact that higher densities exhaust develop quicker that the lower densities. The first bath is the "developer bath", and the second one, having little or no developer, but still being alkaline, the second bath provides an environment for the carry-over first bath to keep developing the lower densities until complete developer exhaustion, and the higher densities will have ceased developing earlier because they have already exhausted their developer. Because the second bath is done with little or no agitation, can create areas on the film where developer distribution is uneven, causing mottle in some cases. But I will always contend that if 2 bath developer provided any real advantage, Kodak would have marketed one. But they knew that the tonal range of print paper is so much less than film, any advantage is mostly nullified anyway. On unknown films is where there's the greatest advantage. If you have Panatomic X and develop it as Plus X in a 2 bath, or Tri-X developed as Plus-X 2 bath, the former will be overdeveloped and the latter will be underdeveloped. But the 2-bath can better come to the rescue and provide a better chance of having a printable negative. on all.
bluechromis - I use a tweak of highly dilute HC-110 to achieve very low gamma unsharp masks with a nearly straight line. I haven't found any other developer capable of that. It's amazingly versatile in terms of dilution.
Paul - the one thing I dislike about TMX100 is its weak edge effect. So I develop it in Perceptol 1:3 which give the grain just the right amount of extra "tooth". Microdol 1:3 is said to accomplish the same thing, though I haven't tried it. Makes no difference if I use store-bought Perceptol or home-brew. But don't try it with TMY400 or Acros, or you get gross grain. It's a whole different animal at 1:3 than 1:1. Dilute D76 introduces too much sag into the curve of TMX.
In terms of 2-bath development, I just don't see any need for it anymore in my toolbox, especially since I mainly switched to pyro development a long time back. Of today's films, HP5 and Tri-X 320 might be classified as the last semi-thick emulsions, if one wants to experiment.
I believe Photo Engineer disclosed here the secret ingredient X in Microdot-X shortly before he passed and went to the big yellow R&D lab in the sky.I'd be interested in hearing your formula for "home brew" Perceptol. I once tried a formula based on the standard D-23 formula + kosher salt, and reducing the metol to 5g instead of 7.5g. It was supposedly a Microdol "home brew". In actuality, the grain was NOT Microdol grain. The secret ingredients to Microdol X have never been revealed as far as I know. but kosher salt ain't it. thank you.
By uniformity I mean evenness of development. There is generally going to be more risk of uneven development with two bath development relative to a properly formulated single bath developer. It might take some experimentation to find the best / most consistent method.
Two bath development can also potentially produce higher fog (which contributes to graininess) since they are usually not formulated for the relatively high alkalinity of the second bath.
The whole deal with 2 bath for the purposes of use on unknown films or getting the most from shadow details, is simply taking advantage of the fact that higher densities exhaust develop quicker that the lower densities. The first bath is the "developer bath", and the second one, having little or no developer, but still being alkaline, the second bath provides an environment for the carry-over first bath to keep developing the lower densities until complete developer exhaustion, and the higher densities will have ceased developing earlier because they have already exhausted their developer. Because the second bath is done with little or no agitation, can create areas on the film where developer distribution is uneven, causing mottle in some cases. But I will always contend that if 2 bath developer provided any real advantage, Kodak would have marketed one. But they knew that the tonal range of print paper is so much less than film, any advantage is mostly nullified anyway. On unknown films is where there's the greatest advantage. If you have Panatomic X and develop it as Plus X in a 2 bath, or Tri-X developed as Plus-X 2 bath, the former will be overdeveloped and the latter will be underdeveloped. But the 2-bath can better come to the rescue and provide a better chance of having a printable negative. on all.
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