硝酸银
Election stain typically stays on skin for 72–96 hours, lasting 2 to 4 weeks on the fingernail and cuticle area. The election ink used puts a permanent mark on the cuticle area which disappears only with the growth of new nail. It can take up to 4 months for the stain to be replaced completely by new nail growth. Stain with concentrations of silver nitrate higher than 18% have been found to have no effect on stain longevity, as even with stronger solutions silver nitrate doesn't have a photosensitive reaction on live skin cells. This means that the stain will wear off as new skin grows. Silver nitrate is an irritant and frequently harmful at 25% solution and above, even being used as an effective, if painful, cauterizing agent in the treatment of rhinitis at that concentration. At 25% the silver nitrate content will also start to precipitate depending on conditions, forming fine crystals which can also be irritating on skin and reducing the active dissolved silver nitrate back to as low as 18%.