Anonymous Castilian artist, The Virgin of the Catholic Kings, Tempera on pine panel, 123 x 112 cm, c. 1490-1493.

Anonymous Castilian artist, Detail of the hidden drawing of the Virgin and Child seen in infra-red light. We can clearly see the outlines of the Virgin and Child and how in a first version the Child was sleeping with his head looking towards the floor. When he finished the painting, the artist decided to paint the Child with his eyes open and looking upwards.

Raphael, The Holy Family (The Pearl), Oil on poplar panel, 147,4 x 116 cm, c. 1518.

Raphael, Detail of the hidden drawing of Saint John the Baptist’s Head, seen in infra-red light. We can see that the artist used a grid to transfer the composition of a preparatory drawing.

Jan Gossaert, called Mabuse,Christ with the Virgin Mary and Saint John the Baptist, c. 1513-1517, Oil and gilding on paper and oak panel, 122 x 133 cm.

Jan Gossaert , Detail of the hidden drawing of the Christ’s hand, seen in infra-red light.