touch-sensitive inks

On August 21, millions in the US will witness a rare celestial event. For the first time in 38 years, the moon will completely block the solar disk for a few minutes, creating a total eclipse of the sun.

To mark the historic event, the United States Postal Service is issuing an inspired postage stamp with a special trick.

Conceived by graphic designer Antonio Alcal√°, the stamp features two layers of photographs. The first image depicts a picture of a total eclipse observed in Libya in 2006 by renowned astrophysicist Fred Espenak. Then, through the magic of thermachromic printing, an image of a full moon emerges when the warmth of your finger touches the black dot.

The commemorative stamp uses special temperature-sensitive inks that have also been used in mood rings, food labels, and color-changing Coors Light beer cans. On the back of the sheet of stamps is a map of the eclipse’s 70-mile shadow path, which will traverse 14 states as it moves east, from Oregon to South Carolina.

via {quartz}


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