A time indicator comprising a first reservoir (13), a migration medium (11) and activating means for bringing liquid from the first reservoir (13) in contact with the migration medium (11) so that after activation the liquid migrates through the migration medium (11) producing a colour change therein. The activating means comprises a second reservoir (16) connected between the first reservoir (13) and the migration medium (11) whereby after activation the liquid travels relatively rapidly from the first reservoir (13) to the second reservoir (16) and then migrates relatively slowly along the length of the migration medium (11) over time.