Wild Winter Ale is the fourth in a limited edition series of seasonal beers released by Danish brewery Mikkeller in 2012. The label, created by Swedish graphic design agency Bedow, features a simple silhouette of a leafy apple tree, printed with thermochromic ink. The ale is meant to be kept refrigerated or at least cold until serving. What makes this label intriquing is that the ink is heat sensitive. As the label gets warm from being held in the drinker’s hand, the tree begins to shed its leaves until only its bare limbs remain.

Thermochromic inks were first popularized in the 1970s, appearing in “mood rings” that changed colors supposedly indicating the wearer’s emotional state. Increasingly, designers are finding creative ways to use heat-sensitive inks in printing.