Acknowledgements
About the author
Introduction
Sources and their information
Study and interpretation of the sources
The original composition of the paint
The paint's original appearance and the artist's original intention
Notes
1. Determining the intentions of painting methods and recipes
Instructions for preserving the original appearance of the painting
Instructions for taking into account the limited compatibility of pigments
Instructions for using differences in hiding power and tinting strength of the pigments
Instructions to compensate for differences in drying time
Instructions for fast and easy painting
Instructions for taking price differences into account
Instructions for indicating light and shade and the rendering of objects
Instructions for simplying the organisation of the representation
Instructions concerning the sequence of painting
Instructions concerning the division of labour within the workshop
Conclusion and summary
Notes
2. Methods used by painters to prevent colour changes described in 16th to early 18th century sources on oil painting techniques
Historical terminology on discoloration
Instructions to prevent discoloration caused by the oil binding medium
The oil binding medium's tendency to turn yellow
Painters' knowledge about the discoloration of oil
Problems with coarsely ground blue pigments
Using a binding medium that is less liable to discolour
Instructions to regulate the amount of oil in the paint layer
Instructions for using intermediary medium layers
Instructions for mixing colours to a lighter shade or a more saturated hue
Developments in methods to combat the discoloration of smalt oil paint
Methods to combat the discoloration of paint caused by the pigment's discoloration
Discoloration of pigments
Historical knowledge on the durability of pigments
Differences of opinion about the colourfastness of pigments
Historical knowledge on the conditions that caused pigments to discolour
The choice between permanent and discolouring pigments
Methods for improving pigments in order to counter discoloration
Methods for constructing the paint layer in order to counter discoloration
Instructions for limiting discolouring pigments to the underpainting
Discussion of differences in the working methods used to combat discoloration
Instructions for a durable application of unstable pigments in the top paint layer
Instructions to combat the discoloration caused by the mixing of incompatible pigments
Knowledge of the incompatibility of pigments
Instructions for using incompatible pigments
Methods to combat discoloration caused by the increasing transparency of oil paint layers
Causes for the increase in transparency of oil paint layers
Historical knowledge on the increasing transparency of oil paint layers
Gaining knowledge about the paint's discoloration
Transfer of and development in knowledge
Ways of gaining knowledge
The guarantee period for colourfastness
Conclusion and summary
Notes
3. Verdigris Glazes in Historical Oil Paintings: Recipes and Techniques
Interpretation of green glazes
Painting instructions for green glazes
Composition of historical verdigris
Producing verdigris
Distilled verdigris
Appreciation of verdigris
The colourfastness of verdigris
Changing colour from blue-green to green
Incompatibility of verdigris
Instructions for glazing with verdigris
Grinding
Oil media
Varnish media
Varnishing the glaze after drying
Adding pigments to the glaze
Methods of applying glazes evenly
Underpainting for verdigris glaze paints
Diminishing use of verdigris in the 17th century
Conclusion and summary
Notes
4. Indigo as a pigment in oil painting and its fading problems
Indigo as a textile dye: production and history
Preparation of natural indigo from indigo plants
Indigo dye
Import of tropical indigo in Europe
Types of indigo pigment used in oil media
Lumps of tropical indigo
Indigo from the flower of the dyer's vat
Indigo pigment from woad leaves
Indigo made from blue wool
Increasing imports of tropical indigo and its growing importance as an artists' pigment
Different qualities of tropical indigo
Regions from which tropical indigo was imported
Assessment of quality of indigo lumps
Assessment of working properties of indigo in oil media
Quality of indigo pigment and colourfastness of indigo paint
Historical assessment of colourfastness of indigo in oil media
Recipes for purification of tropical indigo
Light-ageing tests with synthetic and natural types of indigo
Pure and impure indigo in easel paintings
Views on indigo's lightfastness and painting technique
"Traditional' techniques: indigo restricted to shadow areas and under paint layers
'New' technique: indigo used in top paint layers
Painting techniques for indigo in top paint layers
Mixtures with lead white or chalk
Lead white pigment particle size
Mixtures with smalt
Mixtures with yellow lakes
Binding media and siccatives
Modelling of indigo drapery
Different states of preservation of indigo paint areas
Comparison of paintings
Environmental influences on indigo's colour preservation
Impact of painting technique on indigo's colour preservation
Influence of the binding medium
Influence of the mixtures with lead white and chalk
Influence of the thickness of indigo paint layers
Influence of the pigment volume concentration
Influence of the light or dark underpaint layer
Influence of the overlying varnish
Influence of the particle size
Impact of fading of indigo on the colour harmony and the effect of spatial illusion
Conclusion and summary
Notes
5. Discoloration or chiascuro? An interpretation of the dark areas in Raphaels' Transfiguration of Christ
Views on the chiaroscuro in the Transfiguration
The Vasari camp
First-hand observations by 18th-century authors and the mosaic copy
Anton Mengs
Early 19th-century views
The atmospheric explanation
An error by Raphael's pupils
The use of wrong materials
The darker style and rilievo
After the restoration of 1972-76
The 'expressive' chiaroscuro
Rilievo and the modelling in the Transfiguration
Raphael's late style and rilievo
The modelling in the lower half
Preliminary studies and 16th-century copies
Preliminary studies
Sixteenth-century copies
Light as a means of expression
Divine and earthly lights
Function of light in early 16th-century painting
Possible causes of the darkening
Vasari
Black pigments
Examination of the paint surface
Conclusion and summary
Notes
Appendices
A. Indigo as a pigment in oil painting and its fading: tropical indigo plants
B. Indigo as a pigment in oil painting and its fading: experiments
Materials and preparation of paint reconstructions
Pigments
Media
Paint application
Light-ageing conditions and colour measurements
Colour measurements of samples subjected to light ageing no. 1
Experiments
Light-ageing tests with synthetic and natural types of indigo
Recipes for purification of tropical indigo
Influence of the binding medium
C. MOLART Reports
List of Selected Sources
Bibliography
Index