Infrared range

Infrared radiation is non-visible, and extends from the nominal red edge of the visible spectrum the minimum limits of the range that is just above the microwave portion of the electromagnetic spectrum. The part of the range used for conservation science applications is limited to the area classified as near infrared (NIR: 700 - 1000 nm) and shortwave infrared region (SWIR: 1000 - 2500 nm). Infrared radiation is characterized by its extensive penetration capacity. This, in combination with the fact that many materials reflect infrared radiation or allow its passage through their mass in a different way than is the case with visible light, allows the "reading" of underlying paint layers or other elements usually invisible to the naked eye.