Pentimenti may show that a composition originally had an element, for example, a head or a hand, in a slightly different place, or that an element no longer in the final painting was originally planned. The changes may have been done in the
underdrawing of the painting, or by the visible layers of paint differing from the underdrawing, or by the first painted treatment of the element having been over-painted. Some
pentimenti have always been visible on the final painting with careful inspection; others are revealed by the increasing transparency that some paint acquires after several centuries. Others, especially in the underdrawing, can only be seen with modern methods such as
X-rays and
infrared reflectography and photographs. These are able to record photographically some
pigments, depending on their chemical composition, which remain covered by later paint layers. For example,
white lead, a common pigment, will be detected by X-ray, and
carbon black underdrawings can often be seen with great clarity in infra-red reflectograms. These methods have greatly expanded the number of
pentimenti art historians are aware of, and confirmed that they are very common in the works of many
old masters, from
Jan van Eyck onwards.
is painted over. These marks would not usually be described as pentimenti'' as the subjects are totally different Pentimenti are considered especially important when considering whether a particular painting is the first version by the original artist, or a second version by the artist himself, or his workshop, or a later copyist. Normally, secondary versions or copies will have few if any pentimenti, although this will not always be the case, as in
The Lute Player by
Caravaggio. Like
Rembrandt,
Titian and many other masters, Caravaggio seems rarely to have made preliminary drawings but to have composed straight onto the canvas. The number of
pentimenti found in the work of such masters naturally tends to be higher. Marks revealing a totally different subject, for example in
The Old Guitarist by
Picasso, are not usually described as
pentimenti – the artist has abandoned his "earlier composition" to begin a new one. In cases where a composition has been changed by a later painter or restorer, marks showing the original composition would not be described as
pentimenti either; it must be the original painter who has changed his mind. Evidence of
pentimenti may also help experts determine that the work was not created by a copier or forger since they are more likely to reproduce the original without making changes. ==Usage in English==