Detail of dagger from the Walker Art Gallery's Henry VIII and the underdrawing of the dagger
The exhibition Henry VIII Revealed, held at the Walker Art Gallery in 2003, brought four versions of the definitive Henry VIII portrait together for the first time. All four paintings, from the Walker Art Gallery, Petworth, Chatsworth and Trinity College, were based on the Holbein mural at Whitehall Palace which was destroyed by a fire more than 300 years ago.
The Walker Art Gallery's version is one of the best-known images of the king, but when, how and by whom it was painted has been very much open to speculation. The exhibition provided a great opportunity for conservators, art historians and scientific specialists to try to find some answers.
Processes and discoveries were recorded using different kinds of photography, before, during and after treatment.
Investigations begin with a thorough examination of the structure and surface of the paintings using 'non-destructive' methods. These include using special types of light, such as infrared and ultraviolet, to reveal different features of the paintings. For example infra-red reflectography allowed experts to compare the underdrawings for each of the Henry portraits.