[sbierwagen]

Infrared thermometers like the one used in this article are (typically) calibrated for an emissivity of 0.95. If you use one on a material with a lower emissivity, it'll give inaccurate readings. This can be cheaply solved by sticking a piece of electrical tape on the surface, and measuring that.

http://en.wikipedia.org/wiki/Emissivity

[MurrayHurps]

Fantastic insight. I did have trouble picking up a temperature at certain angles, but at 90 degrees it returned the highest reading, which still wasn't burning my hand so is probably not above the value registered.

Might have gotten away with it because it's stoneware of some kind, but will definitely try a tape patch next time.

[tripzilch]

90 degrees what?

a quick and easy test whether something is below or above ~50 degrees Celsius, is whether it's immediately painful to the touch.

it's the temperature at which most of our proteins start to denature, aka the temperature at which a steak changes from "warm but raw" to "very rare", and therefore the temperature that hurts your fingers.

it's not super accurate of course, but it'll do if you just want to eyeball 53C.

[agoetz]

Bonus: Once you have a couple of data points from the tape method, you can extrapolate the emissivity of the toast itself and calculate a correction factor for your IR gun.