A cleaning article including an agent or reagent, for example a biocidal agent or reagent, which is slowly released therefrom in use of the article and a visual indicator selected to present a change in appearance indicative of the amount of agent or reagent remaining in, or released from, the article. In preferred embodiments, the cleaning article comprises a nonwoven fabric or sponge containing one or more biocides which are slowly released during use, and bearing a crosslinked ink which fades during use at a rate which indicates when the article is no longer reliably biocidal. The invention also relates to a visual indicator for use on a cleaning article containing one or more biocides which are slowly released during use, said indicator consisting of an ink formulation which is crosslinked to a degree selected so that the ink will wear off or fade to a predetermined degree with the amount of usage that causes the biocide concentration to fall below an effective level. The amount of biocidal agent in or on a cleaning device when the agent is depleted or inactivated during use may be determined by comparing the appearance of the used cleaning device with the appearance of a corresponding unused cleaning device or a colour reference.