The radiography of cultural objects is the use of radiography to understand intrinsic details about objects. Most commonly this involves X-rays of paintings to reveal underdrawing, pentimenti alterations in the course of painting or by later restorers, and sometimes previous paintings on the support. Many pigments such as lead white show well in radiographs. X-ray spectromicroscopy has also been used to analyse the reactions of pigments in paintings. For example, in analysing colour degradation in the paintings of van Gogh.
These processes can reveal various details about objects that are not visible to the naked eye. This information, which includes structural elements, aids conservators as they assess object condition and consider treatment plans.
Infrared and ultraviolet light are also useful tools to understand the intrinsic details of certain objects. However, X-rays tend to be more useful for denser objects. The benefit of radiography is that it is not intrusive. Radiography does expose the object to radiation, but these levels are low. In fact, they are much lower than the radiation levels required for medical X-rays. While technicians and staff conducting the X-ray must use protective gear, the object is not damaged during the process. Furthermore, the use of radiography is widely accepted by conservators, art historians, and archaeologists. Several institutions around the world conduct radiography of objects in their collections including the Victoria & Albert Museum in London, England and the Smithsonian, which operates the Museum Conservation Institute.