FORMULARY RESIDUAL SILVER TEST is used to determine if any silver ions remain in a print or on a film strip after fixing. When the test solution is applied to photographic material the sulfide ions in the solution react with any residual silver ions in the material forming a yellow stain indicating the fixing process is inadequate.

The chemical in the kit makes a stock solution which is diluted 1:9 to make more than 1 liter of working solution. The stock solution shelf life is 3 months, although the working solution lasts only 1 week.