Workshop · Subject · Scientific examinations
How Leonard was he painting?
From the prepared panel to the last glaze: a slow, revisable and experimental method, reconstructed using unfinished works, x-rays and infrared reflectography.
The short answer
Leonardo built rather than filled
He started from a carefully prepared support, developed the design and values, then superimposed increasingly thin layers of oil paint. He could move a figure, modify a hand and take a face long after the painting began.
I · The support
Wood, wall and risky experiments
The wooden panel
The majority of preserved paintings are executed on panel. A rigid, prepared and polished surface allows precise drawing and very thin layers. The Mona Lisa is painted on poplar; Ginevra de' Benci is an oil on panel.
The Last Supper Wall
Leonardo does not work according to the traditional fresco on wet coating. He chose a dry process allowing him slow recovery. This freedom of execution, however, contributes to the early fragility of the work.
The Battle of Anghiari
Ancient accounts describe a failed mural experiment. The technical details remain debated: it is better not to repeat as certainty the legend of a simple "melted encaustic".
II · From bottom to top
The anatomy of a six-layer painting
1 · Prepare
A clear, regular and active base
The panel receives a gesso-based preparation then printing layers. On the Virgin of the Rocks of London, the technical study distinguishes the preparation, primings and imprints linked to their handling. The background is not neutral: its brightness passes through the upper layers.
2 · Draw and model
Drawing under painting
Infrared reflectography reveals the covered carbon plots. Leonardo does not always mechanically follow cardboard: he already draws, reformulates and installs volumes through transitions of light and shadow.
Saint Jerome allows us to observe this current thought: some areas are only established, others are already gaining their anatomical strength.
3 · Place the masses
From the whole to the detail
The large relationships of light and dark are organized before finishing. Color does not decorate a finished drawing: it contributes to the modeling, atmosphere and unity of the group.
4 · Correct
Repentances are part of the method
A head, an arm or a hand can change place. Infrared images of the Virgin of the Rocks of London have even revealed a first composition abandoned under the visible scene. In Leonardo, correcting is not repairing an error: it is continuing to think.
III · The binder
Why was oil painting essential?
| Property | What she allows | Effect in Leonardo |
|---|---|---|
| Relatively slow drying | Work on transitions and take over an area. | Continuous modeling, progressive modifications. |
| Modular transparency | Overlap layers allowing light to filter through. | Deep shadows and colorful glazes. |
| Mixture of mediums | Adjust fluidity, shine and working time. | Differences between localized impasto and very fine films. |
| Adhesion on dry preparation | Painting on panel or wall prepared without depending on the drying of a fresco. | Freedom, but risk when a wall process is poorly adapted. |
Walnut oil or flaxseed oil?
Italian painters could use several drying oils and additives. Their identification depends on samples and state of conservation. It is therefore imprudent to attribute a single oil to all the layers and all the works of Leonardo.
IV · The surface
Glaze, sfumato and through light
Glaze is not a coat of varnish
Glaze is a thin, transparent or semi-transparent pictorial layer containing pigment in a binder. It changes the color and value of the underlying layers without completely masking them.
- it deepens a shadow without making it opaque;
- it locally warms or cools a skin tone;
- it softens a transition;
- it contributes to sfumato when multiplied and modulated.
V · Case studies
Four works, four states of the method
Ginevra de' Benci
Early work, oil on panel. The tip of the brush even serves to clarify certain loops, while the landscape announces the atmospheric perspective.
See reproduction →Virgin of the rocks
Reflectography and hyperspectral imaging reveal two underlying designs: the visible composition covers a first abandoned invention.
See reproduction →
The Last Supper
Dry wall work, chosen to obtain the refinements of an easel painting. The counterpart is extremely difficult conservation.
See reproduction →
Saint John the Baptist
In the late work, drawing and color seem to dissolve into shadow. The figure is not surrounded: the light makes it appear.
See reproduction →What scientists see
X-ray, infrared and stratigraphic sections
Underlying drawing
Carbon materials absorb infrared and reveal abandoned lines, hatching and compositions.
Structure and pigments
They help read certain pigments, compositional changes and support elements.
Order of layers
A tiny cut allows you to observe preparation, prints and colored films, but only at the point taken.
Controlled sources
Institutional technical studies
Verrocchio workshop
Underlying design, monochrome modeling, tempera and oil.
ImagingThe Hidden Leonard
First composition under the Virgin of the Rocks.
Technical BulletinPanel and layers
Gesso, primings, underdrawings and processing.
LouvreReflectographies
Carbon design, repentances and first models.
Continue
Technique, style and works
FAQs
Questions on the subject
What was Leonardo painting about?
Mainly on prepared wooden panels. The Last Supper is a major wall exception.
Was he painting on canvas?
The major autograph paintings preserved are mainly on panel or wall; subsequent transfers and media changes sometimes complicate material history.
Was he using oil paint?
Yes. The oil allowed transitions, transparencies and restarts that were difficult to obtain with tempera alone.
What's a glaze?
A thin, translucent pictorial layer that optically modifies the lower layer.
Did he draw before painting?
Yes, but he could profoundly transform the drawing during execution, as the reflectographies show.
Why did The Last Supper deteriorate?
The experimental dry process adhered less lastingly than a real fresco and underwent humidity, environment and successive interventions.
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