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  • The Denver Post

The science behind the color-changing solar eclipse U.S. postage stamps? Fat magic.

Updated: Sep 14, 2020

Colorado’s Chromatic Technologies uses fat to create disappearing ink

Put your finger on the black spot on the new U.S. postage stamp and the darkness vanishes to reveal an image of the full moon. Magic? No. It’s fat.

The nifty thermochromic stamp — created to honor Monday’s total eclipse of the sun and being snapped up by collectors and fun-loving folks everywhere — works like Crisco. At room temperature, the shortening is a gloppy, white paste that liquefies into a clear, shiny soup when warm. The novelty stamp, however, won’t leave fingers oily, black or cold.

“They’re esters. But it’s not like the fat right here,” said Lyle Small, pointing to his stomach, which doesn’t jiggle much at all. “These are special kinds of fat that come from vegetable sources — really specific chemicals with an exact melting point.”

Small, the founder of Chromatic Technologies Inc. in Colorado Springs, and his 54-person team provided the special thermochromic ink for the 60 million solar-eclipse stamps printed this summer by the U.S. Postal Service. It “melts” at around 84.2 degrees Fahrenheit. Also, it is the first U.S. stamp to use heat-activated ink, a technology unavailable 38 years ago — the last time a total solar eclipse was seen in the contiguous U.S. And it has helped spread enthusiasm for science across the nation...

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