Using a "Patch" to Get an Accurate Measurement at Low Emissivity

Another way to get an accurate temperature measurement on a material with a low emissivity rating is to "cover" it with something with a high emissivity rating and let it come to temperature.

A polished metal skillet, for example, can be covered with a thin layer of cooking oil, which has an emissivity rating of 0.95. Be sure to allow time for the cooking oil to come to temperature before taking your measurement. But once they are the same temperature, the highly emissive cooking oil makes checking the skillet temp a snap.

The temperature of other metals can be measured more accurately by spraying a spot with flat black paint or by applying a few pieces of black electrical tape and allowing it to come to temperature (both have an emissivity rating of 0.95). When using this method, however, be very careful that the field of view for your measurement does not extend beyond the blackened spot or your reading will be skewed by the surrounding metal.

This is also a great way to get a reading on a non-organic surface with an infrared thermometer that has fixed emissivity.