Outside temp of vessel of is 40 Deg C and Water inside it is 86 Deg C.. Why? I was boiling water in a steel utensil. 
Used Fluke's IR Gun (59 Max) to measure the temperature of Water inside AND the surface temp of vessel outside. 
The boiling water read 86 Deg C whereas the outside surface temp of vessel read just 40 Deg C. Why is that? If I touched the outside of the vessel it would 'feel' extremely hot but measurement shows just 40 Deg C. So what's going on here?


 A: How these thermometers works is based on the principle of blackbody radiation and the Stefan-Boltzmann law. There is an IR sensor housed inside the thermometer that senses the total power radiated in a window of IR. And this power is related to the temperature of the emitter. But there is also a dependence on emissivity which is governed by the material properties of the emitter like the reflectivity and such. From the wiki page for Infrared Thermometer:

Most surfaces have high emissivity (over 0.9 for most biological surfaces)[citation needed], and most IR thermometers rely on this simplifying assumption; however, reflective surfaces have lower emissivity than non-reflective surfaces. Some sensors have an adjustable emissivity setting, which can be set to measure the temperature of reflective and non-reflective surfaces. A non-adjustable thermometer may be used to measure the temperature of a reflective surface by applying a non-reflective paint or tape, with some loss of accuracy.

So maybe you can modify the emissivity to the right value and see if you get the right temperature. 
A: When the surface is reflecting (like the metal) you are actually measuering then temperature of what can be seen in the reflection, not the reflecting body.
