Argyrol
Argyrol stains must be treated while still fresh. Proceed as follows:
Pepsin.—Sponge with warm water to remove any argyrol that has not soaked into the cloth. Then sprinkle powdered pepsin over the dampened stain. Work it well into the cloth, let stand a half hour or longer, then sponge with water.
Iodine and sodium thiosulfate (“hypo”).—After the above treatment, put a few drops of tincture of iodine on the dampened stain with a glass rod. Let stand for 10 or 15 minutes; then sponge with a solution prepared by dissolving several crystals of sodium thiosulfate in ½ cup of water. Rinse well in water.
To bring back the color changed by an acid, hold the dampened stain in the fumes from an open bottle of ammonia water.