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Synthetic Ice Rinks, Historic Hot Cocoa

by Rachel Petkewich
February 16, 2009 | A version of this story appeared in Volume 87, Issue 7

Polar Rink:
Credit: D. Finnin/AMNH
Where the ice isn't cold.
Credit: D. Finnin/AMNH
Where the ice isn't cold.

Thankfully, nothing like the Ice-nine that threatened to solidify the oceans in Kurt Vonnegut's book "Cat's Cradle," SYNTHETIC ICE is a nonfiction, low-friction alternative to real ice that makes refrigerationless ice-skating rinks possible.

Several companies have been installing synthetic ice, which its makers will identify only with terms like "specially engineered" polymers, in backyard and commercial skating rinks around the world since the 1960s. The earlier materials required sticky silicone coatings that trapped dirt and got on clothes, thereby giving synthetic ice rinks a bad rep. Now, the materials are better, the makers claim.

New York City opened its first synthetic rink in November. The Polar Rink, built on the American Museum of Natural History's outdoor terrace and with a 17-foot polar bear sculpture in the middle, will be open until March 1. No special skates are required.

Synthetic ice gets green points because it is recyclable and doesn't require maintenance with those energy-consuming Zamboni machines the way water-ice rinks do. (In case you are wondering, artificial ice is the technical term for the indoor or outdoor skating surfaces created by freezing water with refrigeration equipment. Only if cold ambient air does the freezing can a rink boast of having natural ice.)

The Polar Rink was set up by Global Synthetic Ice, a company based in sunny Florida that makes a two-part product called SuperGlide. To assemble the rink, installers lay out panels made from a polymer blend with a carefully guarded composition. Then they spray the surface with "glide enhancer," a proprietary spray that is reapplied weekly.

Alison Rohrs described her Polar Rink experience on a blog associated with the print magazine Budget Travel.

"I quickly learned two things: First, synthetic ice is harder to skate on. Second, it's softer when you fall," Rohrs wrote. She also noted that skating across synthetic ice took more leg strength than it does on water-ice, but the surface wasn't wet or cold. Rohrs says she was happy to watch the skaters from the adjacent snack shop, which serves rich hot chocolate.

Speaking of sipping hot cocoa, anthropologist Patricia L. Crown of the University of New Mexico, Albuquerque, and analytical chemist W. Jeffrey Hurst of Hershey Co. have found evidence that the FIRST CHOCOLATE DRINKS arrived in the U.S. around A.D. 1000 (Proc. Natl. Acad. Sci. USA, DOI: 10.1073/pnas.0812817106).

Cylinder jars:
Credit: American Antiquity
Grande hot cocoa cups.
Credit: American Antiquity
Grande hot cocoa cups.

Crown explains that archaeologists had found a particular type of ceramic vessel in the Chaco Canyon of northwestern New Mexico about a century ago. Only about 200 of these vessels called cylinder jars have been found, she says, and archaeologists had suspected they were for a ritual. After Crown learned that jars with similar shapes in the Maya area of Mexico were used to drink cacao, she contacted Hurst to see if he would be willing to run some samples and find out if the Chaco Canyon examples might have held cacao, too.

Cocoa, the base for solid chocolate and hot chocolate drinks, is derived from cacao beans and contains more than 700 compounds. Hurst applied a liquid chromatography/mass spectrometry method that he had previously developed for tracking theobromine, a biomarker for the cacao plant. To extract the residue found on the pottery for testing, he ground up what he and his colleagues describe as "fragmentary artifacts," which are dated to A.D. 1000-1125, added a little hot water, and filtered out the particulate matter. Sure enough, the analytical instruments detected theobromine.

The scientists didn't touch upon the question of when exactly the ritual of drinking hot chocolate after ice skating gained popularity.

Rachel Petkewich wrote this week's column. Please send comments and suggestions to


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