Toronto. We know how to begin film or paper developing – just pour in the developer. But how do we stop the process? The sensitive media absorbs the developer so even draining it off or removing the media won’t stop development promptly.
The secret is to use a chemical process. Development occurs only when the pH factor of the developer is slightly alkaline. Dropping it below seven by adding a bit of acid stops the process on a dime. Traditionally a diluted solution of Acetic Acid (Glacial Acetic Acid is 37 percent) is used. Never heard of the stuff? Try calling it vinegar (11 percent acetic acid in water) and don’t dilute it so much:-)
I know, I know, lazier folk just wash the medium in water.