‘The Origin of the Milky Way’ has a large number of techniques and material samples.
Around 1575 Jupiter, wishing to immortalise the infant Hercules (whose mother was the mortal Alcmene), held him to the breasts of the sleeping Juno. The milk which spurted upwards formed the Milky Way, while some fell downwards giving rise to lilies.
Lilies were once presented on the painting but the base of the original canvas has been cut off.
Support
Oil on canvas
Dimensions 148 cm × 165 cm (58 in × 65 in)
Ground
-appears to be drying oil
A single thin layer of ground which to the unaided eye appears as brown, but under the microscope it can be seen to consist of a brownish matrix of ochre. The particles are not only charcoal black, but multi-coloured pigment particles of lake, vermilion, smalt, azurite, malachite and ultramarine.
Preliminary drawing and underdrawing
There is a drawing on paper once thought to be a sketch for the picture, but it’s now presumed to be a drawing afterward but made before the mutilation of the lower part.
The underdrawing can be seen from the radiographs and it has been carried out in lead white wich a bush. There are many pentimenti on Juno’s body and they have been draped in an earlier stage. Also there is a mass of rough sketches of heads of putti in the lower half the picture. But not all lead white outlines may be preliminary drawing on the dark ground. Tintoretto has a tendency to make alternations in painting so he redraws the contours of the forms either in white, sometimes in black or frequently in red lake. And neither of the black or rad lake would appear in the radiograph, they are only visible in the cross sections because infra-ed photographs only show the black outlining on the surface of the picture.
Pigments
Blue
Natural ultramarine – the blue drapery on the bed and on Jupiter Mixed with lead white in the sky Flesh paint of Juno
Azurite =