42545A Datasheet, PDF (7/8 Pages) Extech Instruments Corporation. – High Temperature InfraRed Thermometer with Laser Pointer

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 42545a, 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
Asphalt
Concrete
Cement
Sand
Soil
Water
Ice
Snow
Glass
Ceramic
Marble
Plaster
Mortar
Brick
Emissivity
0.90 to 0.98
0.94
0.96
0.90
0.92 to 0.96
0.92 to 0.96
0.96 to 0.98
0.83
0.90 to 0.95
0.90 to 0.94
0.94
0.80 to 0.90
0.89 to 0.91
0.93 to 0.96
Material under test
Cloth (black)
Skin (human)
Leather
Charcoal (powder)
Lacquer
Lacquer (matt)
Rubber (black)
Plastic
Timber
Paper
Chromium Oxides
Copper Oxides
Iron Oxides
Textiles
Emissivity
0.98
0.98
0.75 to 0.80
0.96
0.80 to 0.95
0.97
0.94
0.85 to 0.95
0.90
0.70 to 0.94
0.81
0.78
0.78 to 0.82
0.90
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Model 42545A V4.1 02/08