Reacted Chemstrips were placed in an unsealed envelope or in desiccator vials which were opened daily after 1, 2, 3, 4, 5, 6, 7, and 14 days. The time of change of the reading for 2 days in a row by all three observers was noted. Readings in the low and normal range were most stable and can be considered reliable for 2–3 days when protected from light. If in a desiccator tube, the strips can be reliably reread when the tube is opened as long as 7 days later. In a separate study, strips were left exposed on the laboratory bench or placed in a vial and read frequently for 6 h and again at 28 h. This exposure, comparable to the CS being taped to a hospital record, results in reading changes as early as 2 h after reaction.