| abstract |
A product (10, 1 10, 210, 310, 410, 510, 610) includes a container (12, 112, 212, 512, 612), and an indicator (14, 214, 314, 414, 514, 614, 714, 814, 914) within the container, and being adapted, upon contact with air, irreversibly to change a characteristic of the indicator that is visible from outside of the container. Also disclosed are methods of making and of using the product. |