Electro Optical Industries (EOI) uses one of two high emissivity coatings on the surface of its blackbodies.

The EOI mid-temperature coating is used on both cavity and flat plate blackbodies that have a maximum operating temperatures of up to 210 °C.

Read the rest by visiting their webpage at: www.electro-optical.com/eoi_page.asp?h=What%20Is%20Emissivity?