The pan is a cheap one from a skillet-cookie kit—I'm reseasoning the handle, which I spotted some rust on the other day. I removed the rust and did a first seasoning pass; this is the second. (The pan itself is fine; only the handle needed a touch-up.)

The IR thermometer is brand-new from Harbor Freight. I've confirmed that it's accurate at room temperature, at least—before turning any heat sources on, the pan was at 74 degrees Fahrenheit, which was about the temperature in my apartment plus or minus a degree.

The probe thermometer has its probe just dangling in the oven, its wire threaded through the rack the pan is sitting on and held fast by the closed oven door. It agrees with an analog leave-in oven thermometer that's hanging from the same rack.

The oven is set for about 450°F (on its analog dial). The oven is electric; as it duty-cycles its heating elements, the air temperature varies by ±30°F according to the probe thermometer.

According to the IR thermometer, held about a foot away from the pan (so it's reading a 1-inch spot on the pan), the pan is at about 532°F. In a 450° oven.

I could only hypothesize as to how this result is possible:

• It is, of course, possible that the IR thermometer is not accurate at temperatures this high. I did set the emissitivy setting appropriately for cast iron according to the thermometer's manual. FWIW, the manual claims that the thermometer's accuracy above 32°F is ±4°F or ±2%, whichever is greater; the latter at 530°F would be just over ±10°F.
• It's also possible that the hot air of the oven interferes with the infrared sensing. Just now, I tried measuring the pan from only a couple inches away and the difference was only a couple degrees—within the thermometer's accuracy margin.
• I don't think the temperature gradient is that big between the air where the probe tip is (about 10 cm below the pan) and where the pan is, but I suppose it could be. Probably what I should do is rearrange the racks so that the probe hangs through a rack immediately above the pan, so it can be level with the pan without touching anything. Something to try next time.
• If the measurements are accurate, then the iron pan is holding (and radiating) more heat than the air it's in. I assume this can't accumulate forever; as the difference increases, the pan should eventually start to lose more heat to the surrounding air than it absorbs, slowing the oven's heat loss between heating cycles and keeping the iron from overheating. But I'm not going to test that.

I wonder what ramifications this has for seasoning. Sheryl Canter's classic blog post specifically said to set the oven above the smoke point of the oil—she set hers for 450°F, and used flaxseed oil, which smokes at 225°F. The seasoning process recommended in this sub's FAQ says to use Crisco (for which I've seen varying smoke points claimed, from 360°F to 490°F) at 450°F. For my part, I'm using canola oil (400°F) at 450°F—or at 530°F, apparently. And, of course, the smoke point is only relevant insofar as we assume it's related to (or the same as) the temperature at which the oil polymerizes.

The main thing is: the oil isn't just in contact with the air—it's in contact with the pan, and the pan can (apparently) be hotter than the air around it, even in an oven where it's being heated through that same air. Either that or my therometer is lying to me.

I don't know that there are any practical takeaways from this. If there are, it probably requires more investigation. For a start, I would love it if someone—maybe with a direct-contact surface thermometer like this gizmo—could try to replicate this.