Although it is more convenient to use an acid stop bath and fix, simply because they are more readily available, it is far better to keep the whole processing procedure at or near the ph of the developer, and developers are alkaline! Up to now there was little choice; you took your film from an alkaline developer and plunged it into an acid stop, followed by an acid fixer. These radical changes in ph stress the emulsion, and can play havoc with those delicate (and not so delicate) highlights you worked so hard for.

Now there is Alkali-STOP, available only from Monochrome Photography, and designed to work with Prescysol (and other staining developers) and Alkali-FIX, our own alkali fixer.

It is known that an acid environment inhibits the formation of the stain so desirable and effective in producing fine negatives, but keeping the ph within certain tolerances not only enhances the stain, but has other benefits too.

Alkali-Stop is the first genuine, commercially-available alkaline stop bath. It works quickly and readily and produces clean, white highlights and well-balanced midtones. (Suprisingly, an acid stop can give a slight stain in highlight areas, and slightly muddy midtones that do not clear in the fix.)

No matter which film or developer you use (except when lith printing) you will need shorter washing times, meaning a saving on time and water. You do not need a hypo clearing bath for prints, and the toning qualities of prints will be enhanced too.

Alkali-STOP is supplied in a 500ml bottle as a concentrated stock solution. The stock solution can be diluted 1:9 to make a working solution. Immerse films and papers for 30 seconds, agitating continuously, drain and transfer to the fixing bath.

The working solution can be stored and re-used, and each litre will process at least 60 films or 25 8x10 prints. Total capacity is therefore approximately 600 films or 250 prints