Pentimento

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.

[2] 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.

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.

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.

[5] Several examples by Leonardo da Vinci can be found in his Salvator Mundi, which was sold to a private collector for more than $450 million at Christie's.

A work by Caravaggio, The Cardsharps has a number of typical minor pentimenti, altering the position of the figure on the right, which are revealed by infra-red reflectograms.

[9][10] The painting depicts the Roman goddess of spring, thought to be modelled on his deceased wife Saskia, and has elements of pentimento, in a double hat brim where the artist overpainted.

Pentimenti were visible once the old varnish was removed, including alterations to the curve of the back of the female nude and one of the male figures' cap, suggesting that the Courtauld picture is a preparatory work.