Quickly washing a silver nitrate spill with liberal amounts of water may remove most of it before it stains. Once the silver nitrate has soaked into skin or fabric, dries and is exposed to light, it turns black.
Silver nitrate stains on skin are temporary and wear off in a few days. As the dead skin cells slough off and are replaced by new cells, the stained area fades and disappears.
There are products that remove the silver nitrate reside on fabrics caused by spills of photo and X-ray developers. Stain removing products, such as ExGo, should be tested on an inconspicuous spot before being applied to fabric or other surfaces. Apply the stain removing product to the stain. When the stain disappears, rinse thoroughly with water.
When using stain removers, follow the manufacturer's directions carefully. Apply in a well-ventilated location, and wear gloves and safety goggles.