Methods of examination

Technical examination and the electromagnetic spectrum

The human eye is sensitive to only a small region of the electromagnetic spectrum. Forms of radiation can be distinguished by wavelength, and range from kilometers-long radio waves to very short gamma waves that are measured in nanometers (one nanometer equals one billionth of a meter). For more information about the electromagnetic spectrum, click here.

The narrow band of visible light ranges between violet (380 nm) and red (750 nm). Technical examination of a work of art also uses regions of the spectrum other than visible light. Infrared light, ultraviolet light and X-rays can provide valuable information on a painting's condition, on earlier stages of its production, and on later alterations.

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