SPUR Stop Bath is an odourless stop bath, 500 ml concentrate, for film and paper.
What it is for
A plain working stop bath with no smell. Its job is to halt development on the second you choose and to keep alkaline developer out of the fixer, where it would shorten its life.
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.
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
It has no indicator, so exhaustion is judged by counting prints rather than by colour. If that is awkward, take an indicator version.
