Photography Formulary Amidol Developer is regarded as one of the finest developers available. It produces rich, strong, black tones which are slightly cool.
Although amidol is an excellent developer, it has a number of drawbacks. It is toxic and expensive. It does not keep well in solution. (Its useful life is about 2-3 hours.) And because amidol stains everything it comes into contact with, it is not pleasant to work with. Formulary Amidol Paper Developer is very similar to Formulary Edward Weston's Paper Developer (Catalog number 02- 0010).
Weston's amidol developer contains citric acid and more restrainer (potassium bromide) than does Formulary Amidol Paper Developer. The additional restrainer in Weston's Amidol Developer results in prints with greater contrast. Because Formulary Amidol Paper Developer is not acidic, it is a more vigorous developer than is Weston's Amidol.
Caution: Amidol is a poison and must be used with caution. It is probably absorbed through the skin so the use of tongs or disposable rubber gloves is recommended when working with amidol solutions.
Amidol stains. Staining is due to the air oxidation of the free base of amidol which is present in neutral or basic solution. Soap, for example, is sufficiently alkaline to cause the amidol hydrochloride salt to be converted to the free base which will then oxidize rapidly forming the staining products.
In cleaning a darkroom after amidol use, first wash with water (amidol is very water-soluble) and then wash with a 2% solution of hydrochloric acid.
The acid wash ensures that the amidol remains in the salt form. Once amidol has been oxidized and has stained, there is not much that can be done.
If an amidol solution should be spilled on the skin, wash the area first with water, then a 2% solution of hydrochloric acid, and finally with soap and water.