> ...intuitively since glass changes temperature more slowly it is naturally less prone to hot spots. You've got it backwards. This is a well-known principle

> ...intuitively since glass changes temperature more slowly it is naturally less prone to hot spots. You've got it backwards. This is a well-known principle in cookware construction, and it's the whole reason that copper and aluminum clad cookware exists. Al and Cu spread heat more quickly, and thus farther across the pan body before it's conducted or radiated away. Remember that the heat isn't just building up in the pan forever; it's dissipated nearly as fast as it's supplied. The heat is conducted to the food in the pan, and in the case of glass it's also being quickly radiated away due to the material's high emissivity and transparence to IR at low-single-micron wavelengths. Thicker glass is generally even worse just because it takes so long to heat up, so the parts that are farther from the flame never reach cooking temperature, while the closer parts are scorching hot. Look up any review of cookware where they use thermal imaging, and you'll the see the results of thermal conductivity on heating evenness. A pan that uses a lot of aluminum or copper will have a much more evenly heated surface than a pan made only of cast iron or steel. And glass is a hundred times worse yet.