RayTek RAYCMLTJM Operating Instructions Manual page 37

Appendix
Emissivity values shown in the table are only approximate, since several
parameters may affect the emissivity of a material. These include the
following:
1. Temperature
2. Angle of measurement
3. Geometry (plane, concave, convex)
4. Thickness
5. Surface quality (polished, rough, oxidized, sandblasted)
6. Spectral range of measurement
7. Transmissivity (e.g. thin films plastics)
37
Rev. B 06/2011
CM