The Chemistry of Art > 1. Pigments in Painting > The Processes Used >
The processes used and the chemistry involved to prepare and attach pigments to surfaces in a named example of medieval or earlier artwork
Name: Saint John the Baptist with St John the Evangelist and Saint James
Date: 1365
Outline:
- Altarpiece from Florentine church owned by knights of Malta
- Expensive commission with large amounts of ultramarine and gold
Composition:
- Much of the painting is gilded and coated with gold
- Areas coated with mixture of iron (III) oxide and egg white before gilding
- Gold leaf added using egg white ‘glue’ then polished
- Floor covering was gilded then painted over with red lead in egg tempura
- Decorative flowers and birds was coated with ultramarine in egg tempera
- Wet paint scraped away from flowers to reveal gold below
John the Baptist: (Central)
- Robes are crimson lake using cochineal with layers of white lead
- Robe lining was coated with ultramarine
Saint James:
- Ultramarine robes
Saint John the Evangelist (Left)
- Ultramarine mixed with lead tin yellow robes
- Some sections of book and cloak lining was blackened due to exposure to sunlight forming mercury (II) sulfide
Flesh:
- Underpaint of green earth
- Additional layer of brown and red earth
- Green tinge to flesh due to certain factors such as years of wear caused by polishing and egg tempura growing transparent with age