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No you don't. Glass is nearly the worst possible material for stovetop cooking. With thermal conductivity roughly 1/70 that of cast iron, it's impossible to c

No you don't. Glass is nearly the worst possible material for stovetop cooking. With thermal conductivity roughly 1/70 that of cast iron, it's impossible to cook on a range without burning the food, and that combined with a relatively low heat capacity makes it useless even for searing. On top of that, glass seems to be a uniquely sticky cooking surface. It's far stickier than unseasoned steel or aluminum. I have several pieces of Visions. I would never, ever use them on a range. I use them exclusively in the oven, where the IR transmittance of the glass is useful, and the uniform surrounding temperature makes the poor thermal conductivity a non-issue.

dasil003 8y ago
How does lower thermal connectivity cause the food to burn easier? FWIW, when I was a kid we had pyrex bowls with clip-on handles for stovetop heating. Yes, you wouldn't cook with it, but great for re-heating food.
- baddox 8y ago
  Presumably it causes food to burn easier because the areas directly touching the flame/heating element become the temperature of the heating element, rather than spreading the heat out across the surface of the container.
  - code_duck 8y ago
    I would think the dense mass of the pan slowly becomes hot and holds a fair bit of heat. This should be a fairly gentle way to cook, but have the same disadvantages of an electric stove top versus gas - slower to respond to range setting changes. When you turn the stove down the glass would take longer to radiate the heat it absorbed into the food than metal would. Not sure about the mass of typical pans of each material, or heat retention potential of glass vs steel/copper. Slower response to lowering heat could cause food to be burnt. I haven’t used glass cookware, though I always thought it looked cool as a kid. I do have 20 years of glassblowing experience though.
    - nate_meurer 8y ago
      > I would think the dense mass of the pan slowly becomes hot and holds a fair bit of heat. It doesn't work that way. The thermal conductivity of glass is so low, the heat doesn't have a chance to spread before being lost to radiation and conduction to the contents of the pan. Glass has high emissivity, and it's at least somewhat transparent, so heat rapidly radiates from the whole bulk of the material. The result is scorching hot spots directly over the flames or coils, while the rest of the pan remains too cool to cook. Glass also has relatively low volumetric heat capacity, meaning a layer of glass holds much less heat than the same thickness of steel or aluminum. Glass really has the worst combination of characteristics for stovetop cooking. There's a reason nobody uses it.
      - code_duck 8y ago
        Makes sense that it would be hottest directly near the flame source - the low conductivity assures that. I’m sure this would be clear if I tried it. Some in the glass community cook in 110 mm tubes of Pyrex at parties. This is also a commercial product (baking cylindrical loaves!). The tubes are rotated like a rotisserie, and the glass is very thin. It works quite well, but we don’t tend to do this outside of glassblowing camp. As far as the thickness, the glass pans are much thicker than typical metal pans, probably for that reason as well as many others. I have some metal pans that are maybe 2mm and they are awful about hot spots. I think the glass pans are about twice as thick as my cast iron Dutch oven, but we’d have to measure. I think the worst aspect is chipping - one chip and the whole thing should be thrown away (one could flamepolish and anneal it, but that’s unlikely for consumers).
        nate_meurer 8y ago
        Interesting. I love glass blowing. Maybe I'll learn about it some day. Borosilicate and aluminosilicate cookware is actually pretty tolerant of chipping, because pieces tend to be thoroughly annealed. Tempered soda-lime, on the other hand, is not, so it has tremendous internal stress that makes it much tougher than borosilicate, but once it does chip it's liable to shatter explosively. Like Prince Rupert's drops. Hey, you want to see something cool? You'll appreciate this since you work with the stuff. Go to 2 min 45 sec in the video at https://www.youtube.com/watch?v=xe-f4gokRBs https://www.youtube.com/watch?v=xe-f4gokRBs. High speed video of one of these things exploding. Kinda blew my mind.
  - dasil003 8y ago
    Yeah that makes some sense, but I'm skeptical. Like the sibling comment here, I have glassblowing experience and intuitively since glass changes temperature more slowly it is naturally less prone to hot spots. Also, it is generally thicker than most metal cookware which means more distance between the heating element and the food to disperse the head. Speaking from experience, touching a 250°C oven heating element will generally burn you worse than touching 600°C borosilicate glass, strong spinal reflex from the former notwithstanding.
    - nate_meurer 8y ago
      > ...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.
      - baddox 8y ago
        I don’t have much experience with cooking, but this sounds correct to me from what I know about thermodynamics. After all, air has much less thermal conductivity than glass, but if you stick a potato over an open flame you expect a spot on the potato to burn, rather than all the air to slowly heat up and heat the potato evenly.
        8y ago

dasil003 8y ago

How does lower thermal connectivity cause the food to burn easier? FWIW, when I was a kid we had pyrex bowls with clip-on handles for stovetop heating. Yes, you wouldn't cook with it, but great for re-heating food.

baddox 8y ago
Presumably it causes food to burn easier because the areas directly touching the flame/heating element become the temperature of the heating element, rather than spreading the heat out across the surface of the container.
- code_duck 8y ago
  I would think the dense mass of the pan slowly becomes hot and holds a fair bit of heat. This should be a fairly gentle way to cook, but have the same disadvantages of an electric stove top versus gas - slower to respond to range setting changes. When you turn the stove down the glass would take longer to radiate the heat it absorbed into the food than metal would. Not sure about the mass of typical pans of each material, or heat retention potential of glass vs steel/copper. Slower response to lowering heat could cause food to be burnt. I haven’t used glass cookware, though I always thought it looked cool as a kid. I do have 20 years of glassblowing experience though.
  - nate_meurer 8y ago
    > I would think the dense mass of the pan slowly becomes hot and holds a fair bit of heat. It doesn't work that way. The thermal conductivity of glass is so low, the heat doesn't have a chance to spread before being lost to radiation and conduction to the contents of the pan. Glass has high emissivity, and it's at least somewhat transparent, so heat rapidly radiates from the whole bulk of the material. The result is scorching hot spots directly over the flames or coils, while the rest of the pan remains too cool to cook. Glass also has relatively low volumetric heat capacity, meaning a layer of glass holds much less heat than the same thickness of steel or aluminum. Glass really has the worst combination of characteristics for stovetop cooking. There's a reason nobody uses it.
    - code_duck 8y ago
      Makes sense that it would be hottest directly near the flame source - the low conductivity assures that. I’m sure this would be clear if I tried it. Some in the glass community cook in 110 mm tubes of Pyrex at parties. This is also a commercial product (baking cylindrical loaves!). The tubes are rotated like a rotisserie, and the glass is very thin. It works quite well, but we don’t tend to do this outside of glassblowing camp. As far as the thickness, the glass pans are much thicker than typical metal pans, probably for that reason as well as many others. I have some metal pans that are maybe 2mm and they are awful about hot spots. I think the glass pans are about twice as thick as my cast iron Dutch oven, but we’d have to measure. I think the worst aspect is chipping - one chip and the whole thing should be thrown away (one could flamepolish and anneal it, but that’s unlikely for consumers).
      - nate_meurer 8y ago
        Interesting. I love glass blowing. Maybe I'll learn about it some day. Borosilicate and aluminosilicate cookware is actually pretty tolerant of chipping, because pieces tend to be thoroughly annealed. Tempered soda-lime, on the other hand, is not, so it has tremendous internal stress that makes it much tougher than borosilicate, but once it does chip it's liable to shatter explosively. Like Prince Rupert's drops. Hey, you want to see something cool? You'll appreciate this since you work with the stuff. Go to 2 min 45 sec in the video at https://www.youtube.com/watch?v=xe-f4gokRBs https://www.youtube.com/watch?v=xe-f4gokRBs. High speed video of one of these things exploding. Kinda blew my mind.
- dasil003 8y ago
  Yeah that makes some sense, but I'm skeptical. Like the sibling comment here, I have glassblowing experience and intuitively since glass changes temperature more slowly it is naturally less prone to hot spots. Also, it is generally thicker than most metal cookware which means more distance between the heating element and the food to disperse the head. Speaking from experience, touching a 250°C oven heating element will generally burn you worse than touching 600°C borosilicate glass, strong spinal reflex from the former notwithstanding.
  - nate_meurer 8y ago
    > ...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.
    - baddox 8y ago
      I don’t have much experience with cooking, but this sounds correct to me from what I know about thermodynamics. After all, air has much less thermal conductivity than glass, but if you stick a potato over an open flame you expect a spot on the potato to burn, rather than all the air to slowly heat up and heat the potato evenly.
      - 8y ago