Moersch MZB is a two-bath compensating developer for black and white film making 2 litres of working solution, made in Germany.
What it is for
Two-bath development has always tamed contrast at the cost of sharpness. MZB exists so that trade does not have to be made: it compensates contrast markedly while still producing sharp edge transitions and very fine grain. The negatives come out evenly graded and — what matters at the enlarger — remarkably easy to print. It suits tank and tray development alike.
How to dilute it
The solution is replenishable — kept and reused, with development time extended as it exhausts. Keep count of the films put through it; that is the only way to avoid an underdeveloped roll at the end of its life.
Two-bath means the film passes through two solutions in turn: the first charges the emulsion with developing agent, the second completes development and slows itself down in the highlights. The practical gain is that timing is not critical, and one pair of baths works the same for films of different speeds.
Storage
Sealed concentrate keeps well but dislikes air: the emptier the bottle, the faster it oxidises. Decant the remainder into a smaller bottle, or displace the air — that is what gets a concentrate to its last measure.
How it compares
An alternative to classic two-bath recipes like Stoeckler's, but ready-made and predictable. Against an ordinary one-shot developer, MZB buys freedom in high-contrast subjects — sun and deep shade in the same frame.
