As a negative and positive developer, amidol enjoys a certain popularity on account of its freedom from fog, good tonal reproduction and universal use, as well as its capacity for producing a deep velvety black on bromide papers.

Focal Amidol universal developer, stock solution
Mix chemicals in order.
Sodium sulphite, anhydrous25grams
Potassium bromide1gram
Water to make1liter
For use take 100 ml of stock solution and add:

Note: It is advisable to add the amidol to the stock solution just before the developer is to be used. Do not dilute.

Times for development:

  1. For plates and films: 3 – 5 minutes. The image appears quickly but the negative must be thoroughly developed, since the density tends to weaken in the fixing bath.
  2. For bromide papers: 1.5 – 2 minutes.
  3. For gaslight contact papers: 45 – 60 seconds.

A solution containing amidol does not keep more than 2 – 3 day; therefore, it is best to make up a stock solution as described, the amidol can then be added immediately before use and no more solution made up than is required at the moment.

Note: As amidol developer contains no sodium carbonate, it does not tend to soften the gelatine of the emusion; it is, therefore, suitable as a tropical developer.