When oxidation occurs in a seasoned tank solution, the sulfide quickly bonds with dissolved silver to form an insoluble silver sulfide. This dark-colored precipitate usually builds up on racks and rollers, and is deposited on the surface of the film or paper being processed. Low wash water flow rates can exacerbate this situation.
Silver sulfide is extremely insoluble and hard to remove.
Failure to adequately flush residual chemicals may result in the release of toxic fumes and gases. Be sure to wear personal protective clothing and equipment. Remove the rack from the machine, and rinse it thoroughly with water to remove all traces of solution. Use enough water to completely wash residual chemicals down the drain. Use the squeeze bottle filled with bleach solution to direct a stream of bleach onto the parts of the racks that require cleaning.