There should be guidance in the instructions as to the performance you should expect.
It say +/-2oC. Although, whilst not specifically mentioning Philip HD4662 kettles (Steve?), the instructions (and how dare you for making me read them ) do say:
These thermometers are preset to an emittance value of 0.95 - the value of most organic substances. This includes such things as wood, cloth, plastics and water. Highly reflective materials with smooth polish surfaces have emittance values much lower than 1.0. To compensate for emissivity when measuring such materials, we recommend using matt black paint, or attaching black tape to the target to soften the reflectiveness.
And sure enough, a piece of black insulation tape on the kettle gave 91oC, much more like it.
I’m not worried about it not working on a brake disk as there’s enough non reflective area near the caliper to give a good reading. Besides, I’m more interested in using it to measure the differences across a tyre and given it’s black, organic and non-reflective it should work peachily.
I’m taking it to Starbucks tomorrow morning. My mate has a normal coffee and I have an extra hot one…always wondered what the difference was!
LOL!
What happens with a lightbulb?
Well the 240V Halogens in the kitchen read 250oC and that’s before any emittance value compensation (because they seem pretty shiny to me!).
My last experiment of the day (because it’s been threatened with confiscation! ) was to see if the black tape made any difference to the radiator’s reading. It didn’t, the cream radiator paint gave the same reading as the bit with the tape on [please, somebody stop me! ].
I’ve just checked mine on the gf doing aerobics and it was monitoring the increasing temp to well over 42oC just fine - just about to send her out on a run to test higher temperatures
Potential here for turning this into a “How hot is your girlfriend?” thread…