Infra-Red

Infrared is similar to visible light, but slightly too long in wavelength for the eye to see: it can, however be photographed.

In conventional infrared photography, an image is recorded using film sensitive to infrared radiation in an ordinary camera. An infrared photograph shows layers just below the visible surface of a painting.

A technique related to infrared photography is infrared reflectography, in which a television camera adapted to receive infrared radiation is connected to a television monitor. An infrared reflectogram, like an infrared photograph, shows layers below the visible surface of a painting, especially carbon black underdrawings.

The two techniques are complementary.