RayTek MARATHON MM SERIES - Page 87

Appendix
Marathon MM Rev. D7 Jul 2017 87
NON-METALS
Emissivity
Material
1 µm
1.6 µm
2.3 µm
5 µm
7.9 µm
8 – 14 µm
Asbestos
0.9
0.8
0.9
0.95
Asphalt
0.95
0.95-1.00
0.95
Basalt
0.7
0.7
Carbon
Unoxidized
0.8-0.95
0,8-0,9
0.8-0.9
0.8-0.9
Graphite
0.8-0.9
0.8-0.9
0.7-0.9
0.45-0.70
0.7-0.8
Carborundum
0.95
0.9
0.9
Ceramic
0.4
0.8-0.95
0.8-0.95
0.95
Clay
0.8-0.95
0.85-0.95
0.95
Coke
0.95-1.00
0.95-1.00
0.95-1.00
0.95-1.00
0.95-1.00
0.95-1.00
Concrete
0.65
0.9
0.9
0.95
Cloth
0.95
0.95
Glass
Plate
0.2
0.98
0.98
0.85
“Gob”
0.4-0.9
0.9
Gravel
0.95
0.95
Gypsum
0.4-0.97
0.8-0.95
Ice
0.98
Limestone
0.4-0.98
0.98
Paint (non-al.)
0.90-1.00
0.9-0.95
Paper (any color)
0.95
0.90-1.00
0.95
Plastic, opaque at 500
µm thickness (20 mils)
0.95
0.95
Rubber
0.9
0.95-1.00
0.95
Sand
0.9
0.9
Snow
0.9
Soil
0.9-0.98
Water
0.93
Wood, Natural
0.9-0.95
0.90-1.00
0.9-0.95
Tab. 14: Typical Emissivity Values
To optimize surface temperature measurements, consider the following guidelines:
 Determine the object emissivity using the instrument which is also to be used for the
measurements.
 Avoid reflections by shielding the object from surrounding temperature sources.
 For higher temperature objects use instruments with the shortest wavelength possible.
 For translucent materials such as plastic foils or glass, assure that the background is uniform
and lower in temperature than the object.