General IRT105 Manuel De L'utilisateur page 12

absorbs 100% of the thermal energy hitting it. An object with
an emissivity of 0.8 absorbs 80% of IR energy and reflects
20% of it. All emissivity values fall between 0 and 1; as a
rule, the shinier the surface, the lower its emissivity. The
default emissivity setting of the IRT105 is 0.95.
To maximize the accuracy of IRT105 measurements, you
should enter the actual emissivity of the target surface via the
front panel buttons and display, as explained on pp. 10 and
11. To do so, first determine the emissivity of the surface
whose temperature you wish to measure from Table 1.
Note from the double entries for aluminum, copper, steel and
asbestos paper in the table that emissivity is only slightly
dependent on temperature. Consequently, you can confidently
use the table's emissivity numbers for your target material
even if it is at a different temperature than specified.
Compensating for emissivity will particularly improve the
accuracy of measurements of surfaces with emissivities
nearer to zero than to the default IRT105 setting of 0.95.
Table 1. Emissivities of common materials
Material
Gold (pure, highly polished)
Aluminum foil
Aluminum disc
Aluminum (household, flat)
Aluminum (polished plate)
Aluminum (rough plate)
Aluminum (oxidized)
Aluminum surfaced roofing
Tin (bright tinned iron sheet)
12
Temperature (°F/°C)
440/227
81/27
81/27
73/27
400/227
1070/577
78/26
390/199
1110/599
100/38
77/25
Emissivity
0.02
0.04
0.18
0.01
0.04
0.06
0.06
0.11
0.19
0.22
0.04