The ExperimentBeer drinking is one of the world’s favorite pastimes. So as the weather started heating up, we felt a scientific duty to investigate this burning beer-related question: what is the most effective beer can cozy?
We took temperature measurements using a digital thermometer with a metal probe. In most of the experiments, the probe was submerged 5.5 cm into the beer, at the approximate midpoint of the can. All experiments were performed outdoors, with ambient temperatures varying from 90F (32.2C) to 103F (39.4C). Except as noted, all beverages used were 12 oz. (355ml) domestic beers. The starting temperatures for the beers ranged between 35.7F (2.1C) and 43.7F (6.5C)

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Results: All of the cozies had some effect and kept beer colder than the uninsulated can. Out of the five, the two that performed the best were the most expensive model, the metal and foam NASCAR cozy, and one of the least expensive, the foam rubber model. The terminal temperatures of the beer in each was 59.3F (15.2C) and 59.5F (15.3C) respectively – about 15 degrees below the final temperature of the naked can (74.3F/23.5C). The neoprene cozy and the plastic NASCAR cozy were both reasonably effective, keeping the beer 9.4 (64.9F/18.3C) and 11.2 (63.1F/17.3C) degrees cooler, respectively. The Coleman can holder was the least effective, keeping the can only 7.2 degrees cooler (67.1F/19.5C)
(more...)There's more to the experiment at the link, including, food- and
meat toy-based cozies, bottle cozies, and knitted cozies.
http://www.myscienceproject.org/beer.html