The United States Postal Service (USPS) will be commemorating the solar eclipse by using Chromatic Technologies Inc. (CTI) inks on their stamps.
According to inkworldmagazine.com, the stamps will come equipped with a thermochromic ink that changes color when in contact with heat. The inks of CTI will allow users to alter the image of the solar eclipse through a simple touch of a thumb.
When the surface of the stamp is raised to 84°F. or higher, the lunar surface will appear. Similarly, when the temperature drops to 77°F and below, it reverts back to the original dark image.
This technology has been exploited by companies such as MolsonCoors, Frito-Lay and Coca Cola since CTI’s inception in 1993. The thermochromic inks are uniquely formulated for use in screen printing, but CTI employs the same technology for use in flexographic, gravure and offset-printing processes. The thermochromic inks are available in multiple colors (and at various activation temperatures), and can also be adapted to change color when exposed to sunlight (photochromic inks).
The stamp marks the upcoming August 21 solar eclipse in the US.