Cake strips are bands of material that wrap around the exterior of a cake pan, providing insulation and keeping cakes from baking unevenly. At least, this is what cake strips intend to do. Cakes usually bake from the outside in, with the edges of the cake baking before the center of the cake because the batter bakes faster when it is in contact with the metal (or glass) of a cake pan. By insulating the sides of a pan, the pan itself heats up less quickly and you end up with a cake that has evenly baked thanks to the heat of the oven and not just the heat of the pan. It is very similar to using a water bath when baking a cheesecake or custard.
A good oven with a reliable oven thermometer and good quality bakeware is often all you need to prevent any baking uneveness, but cake strips say they can help, so Cooks Illustrated set out to test them in their recent (Jan/Feb 2011) issue. They tested Rose’s Heavenly Cake Strip by Rose Levy Beranbaum, Regency Evenbake Cake Strips by Regency Wraps, Magi-Cake Strips by JT Products and Wilton Bake Even Cake Strips, as well as homemade cake strips, with yellow cake and gingerbread recipes. The homemade strips were made by wrapping wet cheesecloth in aluminum foil to form a band and tying it around a pan. The homemade strips worked well, but were somewhat less convenient than using a ready-made strip.
Rose’s Heavenly Cake Strip came out to be the highest rated. This silicone strip slips around both 8- and 9-inch cake pans easily and performed well, keeping cakes even without doming, cracking or creating crusty edges. Regency Evenbake Cake Strips came in as the second choice of the test kitchen, fitting a wide variety of pan sizes and keeping cakes nice and evenly baked. The JT Products strips and the Wilton Strips were not rated as well in the CI test, as they were almost too good at insulating the cakes and produced rounds that were moist and spongy, like steamed cakes, which the test kitchen did not like as much as more tender cakes.