Figure 5. X-radiograph if Venus and
Adonis, showing Titian's use of lead-white
based highlights.
124
Titian
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Figure 4. XRF sp ectrum if purple area on seat of Ve nus. High peaks fo r cobalt and arsenic suggest
the presence if smalt.light microscopy of pigment samples taken from those areas showed them to
contain birefringent particles with a high refractive index (n> 1.66) that
matched lead-white laboratory standard. This conclusion was confirmed by
staining cross sections with Lugol stain. X-radiographs of the painting show
how Titian used the lead white, particularly to enhance the contrasts in his
composition. It helped to make Adonis's silhouette stand out against lighter
areas in the sky, and emphasized the reddish blush on the face of Venus against
the bright crimson shirt of Adonis (Fig. 5).
A sample taken from the sky area showed that there was not very much
pigment present. The sky appeared to be executed in thin glazes over an
anhydrite gesso ground, with the white of the ground showing through. The
finding of the lathlike anhydrite particles came as a surprise since anhydrite
is generally considered to have been used in more southern areas of Italy. In
the Venice region, the dihydrate fo rm was usual. We do not yet have a sat
isfactory explanation fo r this. In samples taken from the sky area, a relatively
large amount of splintery, isotropic particles with low refractive index
(n<1.66) and concoidal fracture could be fo und. These particles were iden
tified again as ground glass that was added by the painter to promote the
drying of the oil.
Green pigments. The greens of the meadow area and the leaves of the trees
were executed in verdigris and copper resinate. There are two predominant
fo rms of verdigris: blue basic copper acetate and neutral, recrystallized copper
acetate. The latter may be produced by a solution of the fo rmer in strong
vinegar. Both fo rms could be used in painting, simply by grinding the pig
ment in oil. Kuhn has fo und that oil paints made of both copper acetates
show a brownish discoloration at the surface after artificial aging, but below
the surface, the strong green color might remain well preserved (12).
We observed the same phenomenon in samples taken from the Getty paint
ing. At the time of the painting's manufacture, the green colors made with
the verdigris must have looked distinctly different from the way they look
now. They must have been much more intense and bluer. In the case of
verdigris-oil paints, the paints do not always just consist of particles dispersed
in a binding medium. Sometimes the copper acetate may partially dissolve in
the medium, fo rming not only physical mixtures, but also new chemical com
positions, like copper oleates, copper resinates, and even copper proteinates.Historical Painting Techniques, Materials, and Studio Practice