Greenlee THH-100 Instruction Manual page 11

Emissivity
Emissivity is the ability of an object to emit infrared energy.
Most objects or surfaces have an emissivity value of about
0.95. This is the preset emissivity value of the THH-100. Some
objects, such as polished or shiny metallic surfaces, may have
much lower emissivity. Using an infrared thermometer to
measure the temperature of such objects will produce
inaccurate results.
Instrument damage hazard:
• Temperature readings will be inaccurate on highly
reflective objects.
• Temperature readings will be inaccurate on objects if
emissivity is not adjusted properly. Follow masking and
emissivity adjustment procedures.
Failure to observe these precautions may result in injury
and may damage the unit.
Masking a Surface to Determine Emissivity
To determine the effect of emissivity on the measurement,
cover the surface with masking tape or flat black paint. (Be
sure to use tape or paint that can withstand the anticipated
temperature.) The emissivity of both these materials is about
0.95. Allow time for the tape or paint to reach the temperature
of the material underneath. Measure the covered area and a
nearby area. The readings should be about the same. If they
are not, the emissivity may affect your measurements.
THH-100
11