A variety of techniques are used to examine a painting. They range from careful examination of a painting's surface with an unaided eye to examinations involving specialized technical equipment that see through paint layers to reveal earlier painting stages, initial sketches, and a painting's support. This allows the conservator to assess the condition of a painting, examine the layer structure, and learn more about the artist's creative process. The examination of a painting utilizes four different forms of electromagnetic radiation: visible light, ultraviolet, x-rays, and infrared. These can be found at the center of the electromagnetic spectrum (seen below).
The Old Guitarist seen with bright light and head loupe (seen below).