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Distance & Spot Size
As the distance (D) from the object increases, the spot size (S) of the area measured by meter becomes larger (see fig. 1 & 2).
Locating a Hot Spot
To find a hot spot, aim the meter outside the area of interest, then scan across with an up and down motion until you locate
hot spot.
Reminders:
Not recommended for use in measuring any shiny or polished metal surfaces (stainless steel, aluminum etc.).
The meter cannot measure through transparent surfaces such as glass. It will measure the surface temperature of the glass
instead. Steam, dust, smoke etc. can prevent accurate measurement by obstructing the meter's optics.
Emissivity:
Most (90% of typical applications) organic materials and painted or oxidized surfaces have an emissivity of 0.95 (pre-set in the
unit). Inaccurate readings will result from measuring shiny or polished metal surfaces. To compensate, cover the surface to be
measured with a masking tape or flat black paint. Allow time for the tape to reach the same temperature as the material
underneath it. Measure the temperature of the tape or painted surface.
Emissivity Values:
Substance
Thermal Emissivity
Asphalt
0.90 – 0.98
Concrete
0.94
Cement
0.96
Sand
0.90
Earth
0.92 – 0.96
Water
0.92 – 0.96
Ice
0.96 – 0.98
Snow
0.83
Glass
0.90 – 0.95
Ceramic
0.90 – 0.94
Marble
0.94
Plaster
0.80 – 0.90
Mortar
0.89 – 0.91
Brick
0.93 – 0.96
Substance
Thermal Emissivity
Cloth (black)
0.98
Human skin
0.98
Leather
0.75 – 0.80
Charcoal (powder)
0.96
Lacquer
0.80 – 0.95
Lacquer (matt)
0.97
Rubber (black)
0.94
Plastic
0.85 – 0.95
Timber
0.90
Paper
0.70 – 0.94
Chromium oxides
0.81
Copper oxides
0.78
Iron oxides
0.78 – 0.82
Textiles
0.90
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