42560-EU-EN-V5.1-9/11
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Emissivity and IR Measurement Theory
IR Thermometers measure the surface temperature of an object. The thermometer’s optics sense
emitted, reflected, and transmitted energy. The thermometer’s electronics translate the information
into a temperature reading which is then displayed on the LCD.
The amount of IR energy emitted by an object is proportional to an object's temperature and its
ability to emit energy. This ability is known as emissivity and is based upon the material of the object
and its surface finish. Emissivity values range from 0.1 for a very reflective object to 1.00 for a flat
black finish. For the Model 42560, the emissivity is adjustable from 0.1 to 1.00. Most organic
materials and painted or oxidized surfaces have an emissivity factor of 0.95. When in doubt, set the
emissivity to 0.95.
Emissivity Factors for Common Materials
Material under test Emissivity Material under test Emissivity
Asphalt 0.90 to 0.98 Cloth (black) 0.98
Concrete 0.94 Skin (human) 0.98
Cement 0.96 Leather 0.75 to 0.80
Sand 0.90 Charcoal (powder) 0.96
Soil 0.92 to 0.96 Lacquer 0.80 to 0.95
Water 0.92 to 0.96 Lacquer (matt) 0.97
Ice 0.96 to 0.98 Rubber (black) 0.94
Snow 0.83 Plastic 0.85 to 0.95
Glass 0.90 to 0.95 Timber 0.90
Ceramic 0.90 to 0.94 Paper 0.70 to 0.94
Marble 0.94 Chromium Oxides 0.81
Plaster 0.80 to 0.90 Copper Oxides 0.78
Mortar 0.89 to 0.91 Iron Oxides 0.78 to 0.82
Brick 0.93 to 0.96 Textiles 0.90
Automatic Emissivity Adjustment
The 42560 has the ability to automatically calibrate the emissivity setting. However, in order to do
so, the temperature of the measured surface must be above 212ºF (100ºC).
Follow the steps below to use the automatic emissivity adjustment feature:
1. Press the MODE button until the EMS (Emissivity) icon appears on the lower LCD line.
2. With meter turned OFF, press and hold the Laser/Backlight button and then press and hold the
MODE button to turn the meter on until the EMS icon begins to blink and the emissivity value is
displayed as dashes “- - - -”.
3. The IR temperature will be displayed on the middle line of the LCD and the Type-K temperature
will be displayed on the lower LCD line.
4. Touch the Type-K sensor to the surface and, at the same time, take an IR reading.
5. When both the IR and the Type-K measurements stabilize, press the AT
E button (doubles as
button). The new emissivity value will now be displayed.
6. Proceed to take measurements.
