Emissivity is the measure of an object's ability to emit infrared energy. Emitted energy indicates the temperature of the object. Emissivity can have a value from 0 (shiny mirror) to 1.0 (blackbody). Most organic, painted, or oxidized surfaces have emissivity values close to 0.95. Majority of Raytek sensors have adjustable emissivity feature to ensure accuracy when measuring other materials such as shiny metals.
If you are using a thermometer with a fixed, preset emissivity of 0.95, and need to measure a shiny object you can compensate by covering the surface to be measured with spray oil, flat black paint or masking tape. Measure the temperature of the taped or painted surface. That is the true temperature.
Please note, these tables are to be used as a guide only as emissivity changes with temperature and surface finish.
Emissivity Table for Non-Metals
Emissivity Table for Metals