Just because they are flexible doesn't mean they are flimsy. The weighted base makes them plenty sturdy. Melt chocolate by standing the bowl in a pan of hot water. One tester, an artist who used silicone for mixing plaster for molds, saw that these bowls could be useful for hard crackle candy making. When the candy mix hardens you can flex the bowl and break up the leftover for fast clean up. He's right. These bowls are heat resistant to 490 degrees, well past the 300 degree mark for hard crackle candy