Depending on what you’re pointing your infrared thermometer at you’re probably going to get a variation in emitted infrared energy. This variation is called emissivity. Emissivity is a measure of a material’s ability to emit infrared energy. It is measured on a scale from just about 0.00 to just below 1.00.
Generally, the closer a material’s emissivity rating is to 1.00, the more that material tends to absorb reflected or ambient infrared energy and emit only its own infrared radiation. Most organic materials, including the by products of plants and animals, have an emissivity rating of 0.95. These are ideal surfaces for accurate temperature readings.
Substances with very low emissivity ratings, like highly polished metals, tend to be very reflective of ambient infrared energy and less effective at emitting their own electromagnetic waves. If you were to point an infrared thermometer with fixed emissivity at the side of a stainless steel pot filled with boiling water, for example, you might get a reading closer to 38°C than 100°C. That’s because the shiny metal is better at reflecting the ambient radiation of the room than it is at emitting its own infrared radiation.
What is fixed emissivity?
Fixed emissivity is a setting on some infrared thermometers, usually of 0.95 or 0.97, that attempts to simplify their operation while leaving them suitable for most material surfaces, including almost all foods. Other infrared thermometers come with adjustable emissivity settings, so you can more accurately prepare your infrared thermometers for the type of surface being measured, particularly when measuring non-organic surfaces.
Mini RayTemp infrared thermometer for routine day-to-day temperature checking compact, lightweight & easy to use temperature range -50 to 330°C laser dot alignment target ratio 12:1
RayTemp 2 Infrared Thermometer high accuracy ±1 °C over 0 to 100 °C FREE traceable certificate of calibration displays ambient temperature records the max/min temperatures designed & built in Britain
RayTemp 6 Infrared Thermometer with circular laser for precise targeting max/min, display hold & backlight functions adjustable emissivity for multi-surface temperature range -60 to 550 °C robust IP54 splashproof casing
RayTemp® 38 infrared non-contact thermometer for measuring small surface areas at greater distances auto-power off & backlight functions wide temperature range -59.9 to 999.9°C robust housing for durability high target ratio of 50:1 RayTemp® 38 is exclusive of probe