![I feel like this is a good one. I put this ceramic mug in the microwave sometimes and overtime this black sludge appears in the outside? What is it and why do I feel like this is a good one. I put this ceramic mug in the microwave sometimes and overtime this black sludge appears in the outside? What is it and why do](https://preview.redd.it/omkr9m7r1ld01.jpg?auto=webp&s=5b4fab7ea6f97c9b65983ebbbb4038008faa7ac2)
I feel like this is a good one. I put this ceramic mug in the microwave sometimes and overtime this black sludge appears in the outside? What is it and why do
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