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.
| Ingredient | Quantity | |
| Mix chemicals in order. | ||
| Sodium sulphite, anhydrous | 25 | grams |
| Potassium bromide | 1 | gram |
| Water to make | 1 | liter |
| For use take 100 ml of stock solution and add: | ||
| Amidol | 0.5 | grams |
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:
- 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.
- For bromide papers: 1.5 – 2 minutes.
- 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.