Disclosed is an ink composition which is suitable for ink jet printing and comprising an organic solvent, for example, methanol, a water-soluble resin, a water-soluble dye, and optionally a surfactant, wherein, if water is present, it is present in an amount less than 50% by weight of the ink composition. The ink composition is suitable for printing messages on substrates such as diaper outer liner fabrics. The printed messages are removed upon contact with water or urine or other aqueous body fluid, thereby providing an indication of diaper wetness.