Published January 1, 2011. From Cook's Illustrated.
We tested four brands of cake strips to see which baked the most even, moist cakes.
Perfectly level, evenly baked cakes can elude even the most practiced bakers. Cake strips, also known as magic strips, are engineered to correct uneven baking by applying an insulating layer around the outside of a cake pan. Without insulation from the oven’s heat, the edges bake more quickly while the center tends to dome, crack, or rise quickly before collapsing. And while cake knives and other tools can level off cakes meant for layering, there’s no remedy for an underdone, gummy interior if the edges have already dried out.
We wrapped four brands of cake strips, made from silicone or aluminized fabric that’s been soaked in water, around 8-inch square, 9-inch round, and 13 by 9-inch pans filled with cake batter, and compared them with cakes wrapped with homemade cake strips: damp cheesecloth or newspaper folded into 2-inch strips of aluminum foil and tied with twine. We looked for cracked, dark centers on our Classic Gingerbread Cake (Jan./Feb. 2011) and high, domed centers on Fluffy Yellow Layer Cake (March/April 2008). And just to see if they could accomplish even baking from the edges all the way to the middle of a large sheet cake, we baked yellow cakes in 13 by 9-inch metal pans fitted with each of the strips. Then we baked cakes without strips and compared them all (a grand total of 26) side by side to see which ones passed our test.
One of the biggest factors determining the success or failure of a cake strip: how evenly it wrapped around a pan. A strip too short to reach around the pan’s perimeter had to be doubled up with a second band, and anywhere the pieces overlapped led to uneven baking. For example, one product encircles a 9-inch cake round without overlapping, and the cakes from that vessel emerged evenly baked and level. But when we overlapped a pair of these strips to fit around an 8-inch square pan, the gingerbread it contained rose almost ¼ inch higher on the side with strips overlapping. And it wasn’t just that brand; strips from other manufacturers that had to double up and overlap led to the same results, despite reassurance two of the packages that overlapping wouldn’t interfere with effectiveness. We had much better results with a silicone band and our homemade strips. The former snaps onto a round or square pan like a rubber band, while the latter can be fashioned to any length, meaning that overlapping is never an issue. In both cases, the insulated rings ensured evenly baked yellow cakes; Our winning cake strip produced almost-perfect gingerbread, save for a slightly domed center.
Cake strips that were easy to affix without slipping or falling off in the transfer to the oven had a clear advantage. We had no patience when it came to fiddling with the tight cross-turning clips on the one product, which resembled tricky paper clips and took nimble fingers to open. Worse, the thin, sharp pins that fastened other strips had to be pushed through the strips’ thick fabric with some force, making it easy to stick testers’ fingers. Velcro tabs on the one product were handy for belting around 13 by 9-inch pans; anything smaller and the tabs were too short for the strips to meet and overlap. In fact, this was the one instance when our winner's silicone band disappointed; though it requires no wriggling or pinning, and soaking it for a minute or two under hot water makes it pliable enough to stretch around a 9-inch square pan (it shrinks back to original size after cooling), it won’t fit anything larger.
But properly dressing the pans was only half the battle. When it came to actually baking with these bands, some of them insulated too well, turning gingerbread into steamed pudding and yellow cakes soft and spongy, even on the sides. The key here: water retention. Three of the four strips were made from aluminized fabric and came with instructions for presoaking followed by gentle squeezing to remove excess water. But depending on the thickness of the strip, that still left a lot of moisture.
To see how much water we were adding, we weighed each set dry and then soaked, gently squeezing them (as instructed) before weighing them again. Two brand's strips were still swelled with water after baking, as evidenced by the steam they gave off after the pans came out of the oven and by the spongy, pale edges on our cakes. But our homemade cake strips, which weighed just half an ounce more when dampened, yielded perfectly risen cakes with no cracks or shadows and with interiors that were consistently moist from edges to centers.
Given that homemade strips can be made for pennies on the dollar and custom-cut for any size pan, it’s our go-to choice. But for serious bakers who want to keep a durable, reusable strip at the ready, our winner makes the baking process a piece of cake.