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TECHNICAL SUPPORT
Emissivity
What
is Emissivity?
Physics
of Emissivity
Affects
of Emissivity
 Emissivity
Examples
Increasing
Emissivity
Calculating
Emissivity
Emissivity
Table
Emissivity
Testing
 support@optotherm.com
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 Emissivity Examples
A material’s
emissivity can vary at different wavelengths. Most materials, however,
have relatively uniform emissivity throughout the wavelength range in
which thermal imagers operate. For example, the emissivity of most
plastics, ceramics, and metals does not vary significantly throughout
the wavelength range of 7 to 14µm.
Different materials can have widely different emissivity values within the
range of 0 to 1.00 (see table 1). Many common materials including plastics,
ceramics, water, and organic materials have high emissivity. Uncoated
metals may have very low emissivity. Polished stainless steel, for example,
has an emissivity of approximately 0.1 and therefore emits only one tenth
the amount of energy of a blackbody at the same temperature.
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Material |
Emissivity |
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Human Skin |
0.98 |
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Water |
0.95 |
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Aluminum (Polished) |
0.10 |
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Aluminum (Anodized) |
0.65 |
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Plastic |
0.93 |
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Ceramic |
0.94 |
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Glass |
0.87 |
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Rubber |
0.90 |
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Cloth |
0.95 |
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