SPUR Dokuspeed SL-N is a two-part developer for document films, an A and B set for 10 films.
What it is for
This is not "another developer" but the mandatory other half of the SPUR DSX film: the maker states plainly that a normal continuous-tone image needs this specific formula. In an ordinary developer a document film gives black and white with almost nothing between; with SL-N it opens up a 14-stop exposure range and resolution up to 600 line pairs per millimetre.
How to dilute it
The A and B parts together process 10 films.
It is a one-shot developer: mix the working solution, use it, discard it. That is the most predictable way to work — every film is developed in fresh solution, so times need no extending from roll to roll.
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
The alternative is Rollei RLC, which solves the same problem for document films in general. But with SPUR DSX specifically, the maker's own pairing is what delivers the datasheet figures.
