Time badges are produced as two parts: an adhesive "front-part" made with white adhesive on a clear film and a paper label "back-part" printed with diagonal red bars. The printing ink is formulated with a dye powder (like the dry toner in laser printers). To issue (and activate) the time badges, the white adhesive front-part is placed over the migrating-ink back-part. The red dye begins to bleed (migrate) into and through the white adhesive, becoming visible on the front of the badge in about eight hours. Overnight, the badge printing turns dark red to show “Expired.” Couresty of David J. Haas
