Emissivity reference paints for high temperature applications

In many cases of radiation thermometry a measure of the surface emissivity can be realised by means of a reference paint applied to the surface to be measured and comparing the radiation from the uncoated surface with the radiation from the reference paint. Alternatively measurements may be taken directly from the reference paint emission. Two paints, HE6 and HE23 have been developed by Rolls-Royce both to be used in air up to 1300 °C. The spectral emissivity of these paints has been measured at IKE in the normal direction and at 30° and 60° incidence on air at normal pressure and temperatures from 700 to 1313 °C. HE6 shows a slightly angle dependent but a virtually temperature independent emissivity at 0.95, whereas the values of HE23 are slightly lower and slightly decreasing with increasing temperature from 0.93 to 0.90. Both HE6 and HE23 are excellent reference paints.