Diego Velzquez was a painter who often would improve on his paintings over time. The changes that painters make on their previously finished work are called pentimenti. Sometimes it is possible to visualize what an original version of a painting looked like by relying on the penetrating power of infrared rays. In the infrared record on the right it can be seen that Velzquez changed the position of Vulcans head and arm and major damage to the painting on the upper left area was repaired.