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IR Measurements and Emissivity
Last Updated: 10/11/2013

IR Measurements and Emissivity

A basic understanding of emissivity and reflectivity of materials is required for using and understanding Infrared temperature measurements. All materials emit thermal energy differently. As an example a shiny stainless steel object may give you a IR temperature reading that you know is wrong. This is because stainless steel has a emissivity coefficient of 0.075. Place a piece of black tape or black paint on the object and you will get a much more accurate reading as Black Tape has an emissivity coefficient of >0.80.

Emissivity + Reflectivity = 1.0 as Reflectivity is the inverse of Emissivity. In general this means the more reflective an object the less thermal emissivity it has. IR thermal measurements rely on the emissivity of the object. Some examples of material emissivity are as follows:

Aluminum Foil 0.04
Asphalt 0.93
Black Paint 0.80 to 0.93
Brick (Red) 0.93
Concrete 0.85
Iron 0.60 to 0.95
Plastics 0.91
Steel Oxidized 0.79
Steel Polished 0.07
Steel galvanized 0.88

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