Emissivity em·is·siv·i·ty n.
The ratio of the radiation emitted by a surface to the radiation emitted by a blackbody at the same temperature. It is therefore a measure of a material’s ability to emit infrared energy. Materials are assigned an emissivity value between 0 and 1.0. Most organic materials such as paints, plastics, fabrics and food have an emissivity value near 0.95. Low cost IR meters typically have a factory fixed emissivity setting of 0.95. The emissivity value of bare metals is considerably lower and so they should be measured with an IR meter that offers adjustable emissivity.