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You would have to heat the PTFE to almost glowing to make it emit fumes. If you tried that with oil you would have an enormous cloud of smoke - and the smoke f

by ars 4y ago

You would have to heat the PTFE to almost glowing to make it emit fumes. If you tried that with oil you would have an enormous cloud of smoke - and the smoke from the oil is MORE toxic than the smoke from the PTFE. So yah, the most nontoxic is completely correct. And BTW, it is far safer for your birds to use PTFE cookware vs oil because you would have to get the PTFE much hotter vs the oil for there to be any issue.

kragen 4y ago
It's true that any foodsafe oil has a smokepoint lower than the temperature needed to degrade PTFE (https://en.wikipedia.org/wiki/Surface_chemistry_of_cooking#Smoke_points_of_oils https://en.wikipedia.org/wiki/Surface_chemistry_of_cooking#S... lists temperatures from 175 degrees for butter to 257 degrees for soybean oil), but in some cases only by a little bit. I don't think it's necessarily true that cooking with PTFE is safer, even if the smoke is more toxic to birds, because the PTFE fumes are invisible, so you can kill your birds before you realize that there's a problem. It's not likely but it's possible. I also don't think it's really true that you have to heat PTFE "to almost glowing". WP says PTFE starts to decompose around 350 degrees (science) and is already a health problem for birds above 250 degrees, killing parakeets at 280 degrees (after four hours of exposure, which was longer than it took burning butter fumes to kill the parakeets). See https://en.wikipedia.org/wiki/Polytetrafluoroethylene#Safety https://en.wikipedia.org/wiki/Polytetrafluoroethylene#Safety. Things don't start to glow until about 525 degrees, or a little hotter if they're very white. The difference between 280 degrees and 525 degrees is even bigger than it sounds in terms of heat input. It's 145 degrees, yes, but at those temperatures radiation (in the infrared) is the dominant form of heat transfer, and radiation is proportional to the fourth power of temperature; at 280 degrees blackbody radiation is 5300 watts per square meter, while to get something up to 525 degrees you have to pump in 23000 watts per square meter, more than a factor of four. The summary is that it takes four times as much heat per minute to make your teflon skillet glow as it takes to heat it up enough to kill your parakeet in four hours, which is about the same temperature that soybean oil starts smoking at, so if you have birds you might want to think about switching to cast iron, or at least always using abundant oil on your teflon so you're guaranteed to notice if you go outside the safe temperature region. None of this is relevant to bike chain lube or dental floss.
dicknuckle 4y ago
No, it only needs to be ~250C

by ars 4y ago

kragen 4y ago

It's true that any foodsafe oil has a smokepoint lower than the temperature needed to degrade PTFE (https://en.wikipedia.org/wiki/Surface_chemistry_of_cooking#Smoke_points_of_oils https://en.wikipedia.org/wiki/Surface_chemistry_of_cooking#S... lists temperatures from 175 degrees for butter to 257 degrees for soybean oil), but in some cases only by a little bit. I don't think it's necessarily true that cooking with PTFE is safer, even if the smoke is more toxic to birds, because the PTFE fumes are invisible, so you can kill your birds before you realize that there's a problem. It's not likely but it's possible. I also don't think it's really true that you have to heat PTFE "to almost glowing". WP says PTFE starts to decompose around 350 degrees (science) and is already a health problem for birds above 250 degrees, killing parakeets at 280 degrees (after four hours of exposure, which was longer than it took burning butter fumes to kill the parakeets). See https://en.wikipedia.org/wiki/Polytetrafluoroethylene#Safety https://en.wikipedia.org/wiki/Polytetrafluoroethylene#Safety. Things don't start to glow until about 525 degrees, or a little hotter if they're very white. The difference between 280 degrees and 525 degrees is even bigger than it sounds in terms of heat input. It's 145 degrees, yes, but at those temperatures radiation (in the infrared) is the dominant form of heat transfer, and radiation is proportional to the fourth power of temperature; at 280 degrees blackbody radiation is 5300 watts per square meter, while to get something up to 525 degrees you have to pump in 23000 watts per square meter, more than a factor of four. The summary is that it takes four times as much heat per minute to make your teflon skillet glow as it takes to heat it up enough to kill your parakeet in four hours, which is about the same temperature that soybean oil starts smoking at, so if you have birds you might want to think about switching to cast iron, or at least always using abundant oil on your teflon so you're guaranteed to notice if you go outside the safe temperature region. None of this is relevant to bike chain lube or dental floss.

dicknuckle 4y ago

No, it only needs to be ~250C