There are three ways to heat a product, namely:

Infrared heaters fall into the radiation category ranging from 0.76 microns through 1000 microns.

Infrared is broken down into three sub-groups, namely short (near), medium, or long (far) wavelengths.

Short wavelength infrared ranges from 0.76 – 2 microns or 7000°F – 2150°F.
Medium wavelength infrared ranges from 2-4 microns or 2150°F – 845°F.
Long wavelength ranges from 4 – 1000 microns or 845°F – below freezing.

The effective infrared heating range is from 1.17 microns (4000°F) through 5.4 microns (500°F). Below 500°F the heat transfer rate is very low and infrared heating becomes less effective for process applications. Temperatures below 500°F are more commonly convection heating applications.

Wavelength and temperature are inversely proportional. As the wavelength goes down, the temperature goes up.

It should be noted that the temperatures discussed above relate to the heater face temperature, not the process temperature. The heater face temperature is typically 2-4 times higher than the required process temperature.