Sterilization indicator

Low-cost telltale composition, which changes from a substantially light color to a substantially dark color under either steam or ethylene oxide sterilization conditions but is otherwise substantially insensitive to normal ambient environmental conditions including daylight, comprises a solution or dried solution of silver nitrate and a buffering quantity of a nitrate preservative selected from the group consisting of nitric acid, sodium nitrate or potassium nitrate. The telltale composition in aqueous alcoholic solution is printable on any substrate without imparting substantial color thereto, but is selectively colorable by the addition of desired pigments or dyes.