2 bath macrodol-x

I hope the magnification tips work for you Gerald. As time goes by we'll have fewer and fewer in depth chemical experts so for our sakes please don't go until you are called to the "other place"

P.S. By the other place I am not referring to Canada

pentaxuser

Dear PE,

I think your latest post gets to the heart of the matter. Within the realms of your particular testing methodology, you have problems with two-bath developers.

In my world of using such developers with the materials available to me, I can achieve the results that I want using my choice of film and the chemicals I choose with no problems.

This, incidentally, is why I fully value manufacturers' initial guidance (it is a great starting point) which is very helpful and insightful but always find that 'real world' tests suggest another way to achieving the results that I desire.

Bests,

David
www.dsallen.de

I never used 2 bath developers. To my understanding (or speculation), the 2nd bath is just a stepped-up alkaline bath for the purpose of exhausting the residual soaked-in developer from the first bath in an attempt to bring the last possible amount of the toe up into the straight line area. But the whole thing is just too much voodoo of variables.

The idea behind two-bath developers is that the film will absorb just enough developing agent(s) from bath A to correctly develop the film. When transferred to bath B the developing agents are activated and work until they are exhausted. At which point development stops. The problem with these developers is similar to that experienced with monobaths, they must be fine tuned for each film in order to produce the best results. Divided developers are better in this respect since contrast and density can be controlled by the time spent in bath A. But the convenience of a two-bath developer is now lost since time and temperature must be controlled by the user.

Well, I should add that bath B should be single use for the best results as it seasons in with bath A very quickly. This means that two runs using the same solutions will not be identical and the deviation will increase with the area processed. This is simply a matter of carry over. The excess part of part A begins to accumulate and turn bath B into a real developer.

And those that say it works well for them, I wonder if they have done a side by side comparison of their two bath with and the corresponding single bath developer under conditions that give the same characteristic curve obtained with both, comparing the grain and sharpness of both.

I would add that it should be done with 2 films, making 2 sets of 2 comparisons.

PE

I have landed on a difficult terrain, but I stay with one film and use Thornton Two Bath and see how it goes.

Sent from my Nexus 7 using Tapatalk

I think you will be pleased.

Nevertheless, it is so fascinating to learn something here.