HT Instruments HT3302 Notice D'utilisation page 29

9. The radiating power or emissivity "  " is a value between 0 and 1 which indicates the
capacity of an object to emit energy in the infrared frequency range. This parameter
depends both on the material the object is made of and on the finishing (painting).
Parameter "  " is set by default to 0.95 because approximately 90% of the objects has
such an radiating power. Determining this parameter is critical when polished or
shiny surfaces are involved. To evaluate emissivity under such conditions, cover the
surface to be measured with masking tape or flat black paint, allow time for the area to
reach the same temperature as the material underneath it and measure with emissivity
set to 1.00. Compare the value read with the value measured by a thermometer with K
contact probe in the same spot, then reduce emissivity value until obtaining the same
temperature value on both thermometers. The following Table 1 shows the emissivity
value of some common materials
Material
Water
Stainless steel
Aluminium foil
Asphalt
Mat black paper
Cement
Cast iron
Chalk
Rubber
Wood
10. The symbol "EMS" flashes on the display. Move the J key to "+" or "-" to set the desired
emissivity value between 0.01 and 1.00 (default EMS value = 0.95). Keep the J key
pressed in position "+" or "-" to quickly scroll through the values.
11. Press the J key to confirm selection and go on to next item.
Fig. 8: Setting the emissivity value of the surface

0.96
0.14
0.09
0.95
0.86
0.97
0.81
0.75
0.95
0.85
Table 1: Emissivity values of common materials
Material
Bricks
Tape
Brass foil
Human skin
PVC plastic
Polycarbonate
Oxydized Copper
Rust
Paint
Earth
EN - 8
HT3302

0.75
0.96
0.06
0.98
0.93
0.80
0.78
0.80
0.90
0.93