Review on Non-Skid Nesting Mixing Bowls Set of 4 with Spouts and Handles - Ideal for Baking, Cooking, and Serving, Tonal Mint by Peter Boisvert

This is maybe the third or fourth time I've used one of the bowls in the microwave. It used to be great. This time it glowed. More specifically, on the rounded line on the underside that it rests on. There was nothing in or on the bowl to burn in the microwave, especially after less than 30 seconds. Before that, the outside and the floor were spotlessly clean. Since I bought it when I moved out a few months ago, I've well past the return deadline. Maybe that's exactly what's defective, in any case I would recommend not leaving it unattended in the microwave.