Historical Painting Techniques, Materials, and Studio Practice

For the early works are executed with a certain f inesse and an incredible
diligence, so that they can be seen from close as well as from a distance
while these last pictures are executed with broad and bold strokes and
smudges, so that from nearby nothing can be seen whereas from a distance
they seem peifect.
In the case of the Venus and Adonis at the Getty, the earlier technique was
used. The paint layers are few and relatively thinly applied. Where visible in
infrared reflectography, the underdrawing seems to have been closely followed.
No significant changes from the carefully planned composition have been
made. Some later additions seem to have been made, however, in areas such
as Adonis's arms and Venus's legs and back. Some areas in the landscape also
appear to be built up with several paint layers. The pigments seem to be
thoroughly ground directly into the binding medium. This contrasts strongly
with the pigments in the National Gallery's Venus and Adonis. Observed
under a stereo microscope, many lumps of pigment are visible, suggesting that
in making the paint, the pigments were not really ground into, but simply
stirred into the oil. Some differences can be noted between the version in
the Getty and the one in the Prado. Judging from the development as described
by the two contemporary comments, the Getty painting is more
loosely executed than the Prado version, and must have been made at a later
date, perhaps around 1560. The National Gallery version can definitely be
considered to have been painted after the Getty and Prado versions.
Paint layers: the pigments
Yellow pigments. The highlights of Adonis's belt were executed in a bright
yellow with occasional small orange-red dots placed on the highlights. When
examined with PLM, samples taken from the area showed that the yellow
consisted of highly birefringent mica-like particles (n>1 .66). The yellow pigment
had all the optical characteristics of orpiment, including a laminated
form and a waxy luster of the fairly large crystalline particles. The identification
of orpiment was confirmed by finding larger amounts of arsenic in
the sample. A small microchemical test showed that the sample also contained
sulfides.
The red dots on Adonis's belt and the orange-red of Adonis's shoe were also
executed in an arsenic-containing pigment realgar. These pigments were
identified by the usual means of microscopic and microchemical analysis. In
addition, the findings were confirmed by XRD and XRF (Fig. 2).
The use of orpiment and realgar in European easel paintings is comparatively
rare, but it is not unusual to find them in Venetian painting; the use of
orpiment occurred more often in manuscript illuminations. This lack of popularity
may be due to the fact that both pigments are highly poisonous, and
good alternatives, such as lead-tin yellow or yellow lakes fo r orpiment or
vermilion for realgar, were readily available. Because of their sulfidic nature,
both orpiment and realgar are not very compatible with many other pigments.
The Theophilus manuscript even states that orpiment cannot be mixed with
any other color because it would destroy them. While realgar was sometimes
used to prevent putrefaction of binding media by bacteria, fungi, and microorganisms,
historical recipes describing the use of realgar as an actual pigment
are extremely rare (7).
Considering their drawbacks, it is surprising to see how frequently these
pigments were used in sixteenth-century Venetian painting. They have been
identified in several paintings by Titian and Giorgione and in many paintings
by Tintoretto and Bassano. The reasons for this preference are not immediately
evident. Both mineral substances could not be fo und in the immediate
vicinity and had to be imported. They are conspicuously absent in paintings
made in the area around Naples where the minerals actually do occur in the
fumaroles near Mount Vesuvius. Their frequent use in sixteenth-century Venice
may relate to the increasing use of oil as the paint medium. The pigment
Birkmaier, Wallert, and Rothe 121