The idea of a two-bath developer isn't new; there are already many different recipes in existence. But until now it was often impossible to combine a good contrast balance with high sharpness in the contures. This problem is now solved with the MZB developer: the developer has a notably contrast-compensating effect while simultaneously producing sharp contour edges and a very fine grain. You'll get evenly-graded negatives, especially remarkeable in how easily they can be enlarged.
The MZB was not only developed for tank development, but also the tray development process. Not every photographer is prepared to work with the Zone System, and in 35mm work this is only somewhat possible. If the negative density is too high, the highlights in the print can't be produced with adequate differentiation if the shadow areas should be differentiated as well.
This problem is even more noticeable in modern emulsions and, with conventional developering methods, can only be solved with shorter developing times. The disavantage of this solution, however, is a reduced useable film speed.
With the MZB, there is a solution. While maintaining the film's usual speed, the contrast curve is bent only in the highlights - when used with the suggested times, by around one zone. Without going into detail about the Zone System, just for the sake of better understanding, let's just say that the curve is slightly flattened from Zone VII on. MZB is so flexible, that an even stronger reduction of the negative density is possible without any loss of film speed.
MZB is very vorgiving of variations in development, particularly in the case of temperature changes. This makes it possible to set the standard developing temperature at 24 ° Celsius. Because the developer is so vorgiving, even users who do not have a way to maintain such a high temperature (such as a warm water bath) during development can use this developer with need for concern. It is sufficient to warm both developer solutions to 24° immediately before development.
The MZB is available as powder for 2x 2 liter stock solution. The stock solution has a shelf life of at least 6 months, even in a partially filled bottle, and in a fully-filled bottle (without breathing room at the top) it lasts for up to a year in our experience. Higher dilutions than those suggested in the instructions are also possible.