Beware of Bad Science

Many manufacturers will cite Wien’s displacement law, proposed in 1896, to validate their claims of infrared spectral output, typically citing 9.4 microns as the ideal. And while Wien’s law does give a good approximation of peak wavelength based on surface temperature, it does not consider the AMOUNT of infrared being produced. Every object above absolute zero degrees, including ice cubes, emit infrared. But clearly, not every object is going to make a good sauna heater.
For example, the human body radiates infrared and if you calculate it using Wiens law you get a peak at 9.4 microns. So if you use Wien’s law and follow this marketing-driven logic to its conclusion, the human body is the perfect infrared emitter and a crowded elevator is the perfect sauna.