Saturday, 9 January 2010

Renaissance Art in Italy

Two 15th Century Italian Paintings on Fine-Weave Supports
and their Relationship to Netherlandish Canvas Painting
In the 15th century and earlier, artists used canvas supports more often than the material evidence that has
come down to us might indicate. In order to paint on canvas, artists used several different techniques. One
of these bears the historical name of Tüchlein. This technique was widely used in the Low Countries and
to a lesser extent in other regions in Europe. With the help of technical analyses, the author examined the
two Italian paintings from the Fogg Art Museum collection -one attributed to Giovanni Canavesio and the
other to the Studio of Sandro Botticelli-, to determine how closely their structure and materials are to the
Tüchlein technique.
1. Introduction
This short communication is the result of a research project conducted at the Straus Center or
Conservation at the Harvard University Art Museums from September 2004 through June 2005. The goal
of the project was to study the technique and materials of two Italian paintings on fine-weave supports in
order to compare them with Northern paintings made using the Tüchlein technique.
The paintings examined are both from the Fogg Art Museum collection (Harvard University Art
Museums): ‘Salvator Mundi’ (c. 1490-1499, 57.15 x 34.93cm; 1930.2) by the Studio of Sandro Botticelli
(Fig.1), and ‘Saint Roche’ (1475-1500, 114.4 x 48.3cm; 1942.271), attributed to Giovanni Canavesio
2. Etymology of the Word Tüchlein
To avoid misunderstandings and to set up a frame of reference, it is important to examine the historical
usage of the term Tüchlein, as well as to give the precise definition that is being used for this research
project. The term ‘Tüchlein’ derives from a quotation in Albrecht Dürer’s diary (Dubois 1997). He made
this entry during his travels to the Low Countries in 1520-1521: In these quotations he mentions the word
Tüchlein [tuch meaning ‘cloth’ and lein meaning ‘small’] three times:
Devolder, ANAGPIC 2005 Paper 2
“[…] I have sold a ‘Madonna’ picture painted on small canvas”/ “I have got 4 florins, 5 stivers for three
small canvases ”/ “I have given the little Portuguese factor, Signor Francisco, my small canvas with the
small child […]”1(Fry 1913).
Modern scholars have linked this term to Vasari’s technical description of a self-portrait by Dürer2, which
Dürer gave to Raphael. This description mentions a guazzo as the medium that strictly translated means
gouache [painting with opaque pigments ground in water, and mixed with gum and honey (Onions
1934)]. Dubois et al. (1997) interprets it as ‘distemper’ [glutinous substance soluble in water; e.g. animal
glue, plant gum and egg]. In addition the description mentions painting on a linen canvas in transparent
Figure 1: (Top left) Studio of Sandro Botticelli, Salvator Mundi
c. 1490-1499
57.15 x 34.93cm., actual
Fogg Art Museum, Friends of the Fogg Art Museum Fund, 1930.2
Figure 2: (Top right) Giovanni Canavesio, Saint Roch
114.4 cm. x 48.3 cm., actual
Fogg Art Museum, Gift of Edward W. Forbes, 1942.271
Devolder, ANAGPIC 2005 Paper 3
colors without white, the image equally visible on both sides and the highlights obtained by using the
color of the, (possibly bleached), canvas (Dubois et al. 1997).
From that point on, for the majority of modern scholars, the word Tüchlein came to represent a specific
technique, although the term was probably used by Dürer to identify only his supports. Unfortunately the
term has been used indiscriminately by art historians to describe canvas paintings made before, during
and after Dürer’s life and painted using many different types of procedures and materials. Scholars such
as Marijnissen (1987), Wolfthal (1989), Dubois & Klaassen (2000) have argued for a distinction between
the different materials and procedures used to make early Netherlandish canvas paintings.
Taking the above in consideration, the proper definition of the Tüchlein technique is:
1. - finely woven linen support with glue size layer and unprimed;
2. - aqueous binding medium (gum/glue);
3. - no varnish.
3. Comparison Between Italy and the Low Countries
Descriptions of 15th–century canvas paintings have been made which emphasize the differences in
materials and procedures used north and South of the Alps. It has been generally assumed that canvas
paintings from South of the Alps tend to have an egg binding medium, a gesso preparation layer, and
often a final varnish layer. These three differences change the paintings’ visual properties and give them a
very different appearance from canvas paintings from the North (Villers 2000).
Andrea Mantegna (c.1431-1506), and to a lesser extent Giovanni Bellini (c.1430-1516), are generally
assumed to be the only Italian artists who painted both in the Tüchlein technique and in the Italian
technique (Villers 1995). Dunkerton (1993) mentions that it is possible that Mantegna saw the Bouts
triptych3, (painted in the Tüchlein technique), in Venice. Such an encounter could have inspired
Mantegna to experiment with a similar technique. It is important to note that the Bouts triptych is only
one of many examples mentioned in written sources listing Netherlandish canvas paintings in 15th century
Italian collections (Nuttal 2004).
Artists in the Low Countries were well aware of the fact that their art was ‘fashionable’ in Italy and they
therefore made many paintings for export. In addition to panel paintings, they exported canvas paintings,
rolled on dowels and shipped in crates (Dunkerton 1993). In order to allow the paintings to be rolled they
used the Tüchlein technique [a gesso priming layer tends to crack during rolling]. Beside the well-known
Devolder, ANAGPIC 2005 Paper 4
fact that Italian artists came into contact with Netherlandish paintings, they also met artists travelling from
the Low Countries (for example: Dürer in Venice, 1506) (Nuttal 2004). Italian painters also travelled to
the Low Countries to study Netherlandish painting procedures, though most documented study trips were
to study oil painting techniques (Nuttal 2004).
With regard to the two paintings examined for this study, we know that Botticelli painted on canvas in an
Italian technique (e.g. ‘The Birth of Venus’ c.1485, tempera on canvas; 172.5 x 278.5 cm, Galleria degli
Uffizi, Florence) but so far we are not aware of any Tüchleins. From Giovanni Canavesio, as far as the
author knows, no paintings on canvas –of any kind- are known to exist.
4. Technical Examination
In order to determine if the paintings from the Fogg Art Museum collection are painted in the Tüchlein
technique, the canvases were studied layer by layer, looking at the support, the presence or absence of a
priming or glue size layer, the medium used and the presence or absence of a varnish4.
4.1. ‘Salvator Mundi’, Studio of Sandro Botticelli
The ‘Salvator Mundi’ painting attributed to the ‘Studio of Sandro Botticelli’ (Fig.1) entered the Fogg Art
Museum collection in 1930 as a Botticelli. Over the years the attribution has changed to ‘copy of
Botticelli’, then to ‘School of Botticelli’ and now to ‘Studio of Botticelli’. Two similar paintings by
Botticelli, painted in egg tempera on panel, are known: one in Detroit and one in Carrara5 (Kanter, et al.
As mentioned earlier, it is known from inventories that the Italian nobility collected Netherlandish
artwork. For example, the inventories of the Medici family and Tomasso Portinari mention Flemish linen
canvas paintings (Nuttal 2004). The Italian nobility were attracted by the different way of representing
themes, both sacred and profane, as well as by the painting style and technique. The Netherlandish type of
the ‘Head of Christ’, with its realistic representation of blood and wounds became a very popular
devotional object in Italy (Nuttal 2004). In order to meet the demand for these images Italian painters
started to make paintings inspired by examples from the Low Countries. In her book ‘From Flanders to
Florence’, Nuttal mentions the Fogg collections `Salvator Mundi` painting:
‘[…] Although possibly not executed in a strictly Netherlandish technique, [it] might be seen as
alluding generically to Netherlandish panni dipinti […]’ and also ‘The choice of a cloth support
was perhaps intended to enhance its ‘Netherlandish’ character’ (Nuttal 2004)
Devolder, ANAGPIC 2005 Paper 5
4.1.1. Support
The support of the painting is a canvas with a fine plain weave of 18 threads per cm. A prominent flaw in
the weave runs through the center of the canvas. The canvas texture plays an important role in the
appearance of the painting.
Two fiber samples were taken and studied with transmitted light microscopy in order to identify the type
of fiber (Fig.3). The fibers do not
twist and they show nodes -a clear
indication of linen (Gettens & Stout
1963). The fibers are Z-spun. It is
important to mention that the painting
has no less than four lining canvasses,
which could affect the analytical
analysis. There appears to be no
ground on the painting and crosssections
give further evidence that no
ground exists. Examination of the
samples under ultra violet light made
the glue size layer applied on the canvas surface visible as a highly fluorescent layer.
4.1.2. Paint Layers & Pigments
In order to examine the paint layers and pigments, x-ray fluorescence (XRF) was first conducted on the
painting. All of the identified pigments corresponded to the palette used in 15th century Italy. Later eight
pigment samples were taken. These samples were mounted in resin blocks and studied using polarized
light microscopy (PLM), under both visible and ultra violet light. Fourier transform infrared spectrometry
(FT-IR) was also conducted on a several paint samples.
Staining tests were carried out to get an indication of the nature of the binding medium: Sudan Black B
for the presence of lipids and Amido Black AB2 for the presence of proteins6. To get more precise data,
samples were taken to undergo GC-MS analysis but at the time of publication these were not completed.
Figure 4 shows a detail of the blue background of the painting. The figure shows an area where the
gilding has fallen off, showing a lighter azurite layer under a darker azurite layer.
Figure 3: Linen fiber sample, Salvator Mundi
Transmitted light microscopy, X 40
Devolder, ANAGPIC 2005 Paper 6
The cross-section taken from this area made this
double azurite layer more evident. Staining with
Amido Black 2 gave positive results for proteins in the
top layer with the fine pigment particles. The FT-IR
analyses identified both animal glue and gum
throughout the whole sample.
It is possible that this is an example of the use of blau
von feldung, a technique recently identified by Heydenreich,
used to decorate monochrome blue passages,
not only on paintings, but also on heraldic shields,
doors, sculptures and walls (Heydenreich 2002). As is
the case here, he found an azurite layer with large
particles in an aqueous, proteinaceous medium. The
specific choice of particle size and medium gives it a
velvety and tactile appearance that contrasts with the
smooth and shiny look of the gold leaf.
Another possible example of this blau von feldung was noted on the small canvas painting in the
Brooklyn Museum (Netherlandish, ‘Madonna and Child’; Brooklyn Museum, NY. 26.5 x 21cm), during
my brief survey of collections looking for other Tüchlein paintings in the U.S.
The green of the Christ’s collar was identified by the use of polarized light microscopy (PLM) as a copper
based green. FT-IR identified the green pigment as atacamite, a basic copper chloride. This basic copper
chloride pigment has been found occasionally on
German and Netherlandish paintings. It is often found
in Asian art. Theophilius describes in his treatise how
to manufacture viride salsum. According to Scott this
is probably principally atacamite (Scott 2002).
Experiments were carried out following Theopilius’
recipe in order to attempt to reproduce the pigment.
Three copper plates were covered with honey (Figs. 5-
6). Sea salt was sprinkled on top of the honey (Fig.7)
Figure 4: Detail of Salvator Mundi, Studio of
Sandro Botticelli
Blue background (blau von feldung?)
Figure 5: Copperplates with buffed up surface
Devolder, ANAGPIC 2005 Paper 7
and the copperplates were suspended in a glass jar. Warm red wine vinegar was poured over them (Fig.8).
The first results were visible after just a few minutes (Fig. 9), but the pigment samples were collected
after four weeks (Fig.10). The pigment obtained was analyzed with the use of a Kaiser Hololab 5000R
Raman Spectrometer with Raman Microprobe attachment with coherent CW Argon/ion and TI/S lasers at
785nm and 514.5nm. Three out of five samples turned out to be atacamite, the other two verdigris. Scott
also stated that the vessel should be closed airtight; otherwise verdigris is obtained (Scott 2002). It is very
possible that the glass jars were not sealed airtight (Fig.11).
Figure 6: Copperplates covered with honey Figure 7: Copperplates sprinkled with sea-salt
Figure 8: (Above left) Pouring of warm red wine vinegar on the suspended copperplates
Figure 9: (Above right) Results after a few minutes (slight green residue)
Devolder, ANAGPIC 2005 Paper 8
4.1.3. Gilding
The gold leaf of Christ’s halo was laid on a yellow mordant layer. FT-IR analyses of this yellowish
mordant indicated the presence of animal glue, gum and raw sienna. XRF analysis from the same area
suggests the presence of azurite, lead-white, ochre, calcium, gold and silver.
4.1.4. Binding Medium
The results for the staining tests on the cross-sections were positive for proteins. FT-IR shows the
possible presence of animal skin glue and possible traces of gum Arabic. The mixture is mentioned in
Jehan Le Begue’s compilation manuscript from 1431, in the section on S. Audemar`s ‘De Coloribus
Faciendis’. This section mentions a recipe that mixes animal skin glue with gum Arabic so it will last
longer (Merrifield 1999).
4.1.5. Coating
There is no evidence of a varnish layer in the cross-sections even though the statutes of the Venetian Arte
dei Pittori -registered in 1278- contain a regulation forbidding the sale of unvarnished painted objects
(Dunkerton 1993). Ceninni mentions varnishing paintings on canvas in his Il libro dell Arte (Cennini) and
Figure 10: (Above left) The copper plates out of the jar
(notice the difference in color between the plates suspended
closer to the vinegar; the lighter green is atacamite and the
others mostly verdigris)
Figure 11: (Right) Showing the glass jar and the not 100%
airtight lid
Devolder, ANAGPIC 2005 Paper 9
Mantegna mentions a varnish from Venice with regard to his canvas paintings for the Studiolo of Isabella
d’Este (Dunkerton 1993). It seems most likely that these references all deal with canvas paintings made in
the Italian technique.
4.2. ‘Saint Roch’ Attributed to Giovanni Canavesio
The ‘Saint Roch’ painting is attributed to Giovanni Canavesio (Fig.2). The curatorial file notes that the
painting was first attributed to Borgognone when it entered the Fogg Art Museum collection in 1942.
Until this study the painting was catalogued as a ‘transfer from panel to canvas’.
Digital Infra Red photography was used to study the painting7. This made several compositional elements
more evident (Figs.12-13). On the left side of the figure the retreating boot and a piece of clothing from a
second figure can be seen. The fragmentary image and the horizontal seam running through the painting
support the hypothesis that the existing painting is a fragment from a larger composition.
4.2.1. Support
The support of the painting is a canvas with a fine plain weave with 22 threads per cm. A horizontal seam
runs through the painting. As mentioned above, this could indicate that the painting is a fragment. In the
15th century the width that could be woven was relatively narrow due to the size of the looms. On the
other hand the length of the textile had no significant restrictions, the use of a horizontal seam would be
of no use if the actual width were the original width, unless the painter used two smaller pieces that he
had in his studio.
Figure 12: (Above left) Detail of Saint Roch, Giovanni Canavesio
Figure 13: (Above right) Detail of Saint Roch taken with Digital Infrared photography, Giovanni Canavesio
Devolder, ANAGPIC 2005 Paper 10
Two fibres samples were studied in
transmitted light with the use of a microscope
(Fig.14). The Z-spun fibers show the characteristics
of linen with nodes and no twists.
(Gettens/Stout 1963). The absence of a
preparation layer is evident in areas with paint
loss. A cross-section from the saint’s left boot
shows clearly that there is no ground present.
By looking at the same sample under ultra
violet light the presence of a glue size layer is
detectable due to its clear fluorescence.
4.2.2. Paint Layers & Pigments
Ten paint samples were taken in order to analyze the paint layers. Additional staining tests and FT-IR was
also done. All of the identified pigments corresponded to those used in 15th century Italy.
The Saint’s mantle is in poor condition and shows the bare canvas, but some pigment particles were
found in the interstices of the canvas. The reason for its bad state of preservation is not clear, but it is
probably due to the materials and procedures used to make this type of painting and poor environmental
conditions. FT-IR data showed a clear match for azurite and possible traces of a red insect lake, which
may have been used to make the mantle look more purple.
4.2.3. Gilding
By studying the saint’s halo under the
microscope some small areas gilded with
gold leaf were found. A sample from this
area was studied under ultraviolet light and
revealed five different layers (Fig.15). The
first is probably the glue size layer. Layers
two and three have similar components (the
more reddish fluorescent layer is possibly
caused by the presence of madder, a red lake
and the white fluorescent layer probably by a
resin). The fourth layer, which looks similar
Figure 14: Linen fiber sample, Saint Roch
Transmitted light microscopy, X 40
Figure 15: (Top) Cross-section from Saint Roch`s golden halo
X 40, photographed under Visible light
Figure 16: (Bottom) Cross-section from Saint Roch`s golden
halo; X 40, photographed under Ultraviolet light
Devolder, ANAGPIC 2005 Paper 11
to the first layer, possibly indicating a glue layer used as an adhesive for the gold leaf. The top layer lies
on top of the gold leaf. Its function is rather unclear; it could be an original paint glaze or later overpaint
that covers the gilding.
FT-IR analysis conducted on this area showed traces of ground gypsum, an animal glue and red earth.
XRF noted the presence of gold, lead white, ochre, calcite and traces of copper. FT-IR analysis on
samples from other areas with gilding (columns) indicated traces of saffron. Saffron was used, probably
as a colorant, in different mordants, according to several treatises in Merrifield’s compilation (Merrifield
4.2.4. Binding Medium
The cross-sections were stained with Amido Black AB2, and gave a clear positive stain for the presence
of proteins. Afterwards the same cross-sections were stained with Sudan Black B. Some of the samples
turned slightly bluish, indicating the minor presence of oils.
4.2.5. Coating
The painting has a dry matte appearance and appears not to have been varnished. Cross-sections show no
evidence of any coating.
5. Conclusion
As mentioned in the introduction, the author defines Tüchlein as: A painting painted with an aqueous
medium, (gum/glue) on a finely woven linen support, which is glue sized and unprimed and left
unvarnished after the painting was finished. Taking all the above results into account it is possible to
formulate an answer to the question: `Can these two paintings be considered similar to the canvas
paintings from the North made in the Tüchlein technique? `.
Before answering the question it is important to state that there is no such thing as the Tüchlein technique,
since the word was originally intended to describe a type of support rather than a technique. However, the
author’s definition serves to define one set of tools, materials, and procedures used historically to produce
canvas paintings. Strict use of this category of paintings might help in reorganising existing information,
thus facilitating future research.
Within the definition of Tüchlein used in this article, we can conclude that both paintings are very close to
the Northern Tüchleins. The staining tests and FT-IR analysis are not the most precise methods of
identifying the nature of binding media. Both made it clear that the binding media for both paintings are
protinacious and the FT-IR analysis indicated a gum and animal glue. Only the GC-MS results can give
more certainty over the binding media used.
Out of all the above we can conclude that it is likely that there were more Italian painters than just
Mantegna and Bellini who followed more Northern procedures than previously thought.
The author would like to thank Teri Hensick, Kate Olivier and Kate Smith for their advice and editing.
Thanks also to the analytical lab from the Straus Center for Conservation, Narayan Khandekar (Senior
Conservation Scientist at Harvard University Art Museums, Katherine Eremin (Conservation Scientist at
Harvard University Art Museum) and Jens Stenger. (Andrew W. Mellon Post-Doctoral Fellow in Conservation
Science at Harvard University Art Museums). Many thanks to Gunnar Heydenreich, Carolyn
Tomkiewicz, Jill Dunkerton. And a special thank-you note to Paul Himmelstein and William Whitney.
1. Original text from Dürers diary from Dubois, H., H. Khanjian, M. Schilling, and A. Wallert. 1997. A
Late Fifteenth Century Italian Tüchlein. Zeitschrift fûr Kunsttechnologie und Konservierung 11: 229.
“[…] hab ich zu kauffen geben auf ein Tüchlein ein-gemahlt Marien Bild”
“Ich hab 4 gulden 5 stüber auß 3 Tüchlein gelöst”
“Ich hab dem klein factor von Portugal, signor Francisco, mein Tüchlein mit dem kindlein
geschenckt […]”
2. Original description of Vasari from idem: 229, 230.
“condotta da lui a guazzo su una tela bisso, che da ogni banda mostrava parimente e senza
biacca i lumi trasparenti, se non che con acquerelli di colori era tinta e machiata e de’ lumi del
panno aveva campato i chiari, la quale cosa maravigliosa a Raffaello.”
3. The triptych got divided over different museums: `Annunciation`, 1450-55, distemper on linen, 90.2 x
74cm in. J. Paul Getty Museum, Malibu/ `Resurrection`, 1450-60, tempera on canvas, 89 x 72.5 cm, Norton
Simon Museum of Art, Pasadena / `The Entombment`, c.1450, distemper on flax canvas, 90.2 x 74.3
cm, National Gallery, London/ scholars dispute the painting from Brussels being part of the same triptych:
`Crucifixion`, 1450-60?, tempera op doek, 181.5 x 153.5cm Musees Royaux des Beaux-Arts, Brussels
4. The XRF analyses were conducted by Kathy Eremin (Conservation Scientist), the fibre and paint samples
from the Salvator Mundi painting were taken by Jens Stenger (Andrew W. Mellon Post-Doctoral Fellow in
Conservation Science. Together they also did the pigment identifications with the Raman Spectrometer. The
FT-IR analyses were conducted by Narayan Khandekar (Senior Conservation Scientist); all three work at the
Straus Center for Conservation at the Harvard University Art Museums.
5. ‘The Resurrected Christ’, c. 1480, Sandro Botticelli; 44.5 x 29cm, Tempera on panel; Detroit Institute of
Arts, Detroit, ‘Man of Sorrows’, c. 1500, Sandro Botticelli; 47.6 x 32.3cm, Tempera on panel; Accademia
Carrara, Bergamo.
6. The used reactive dyes for the staining test: a.) Sudan Black B (SBB): saturated solution SBB in a mixture
of 30ml ethanol and 20 ml distilled water. b.) Amido Black AB2 (AB): 2.70225ml of N acetic acid (glacial
99.99%) in 45 ml of distilled water. 0.61236g of 0.1M sodium acetate in 45 ml of distilled water. 10ml of
glycerine (glycerol 99+%). 0.1g Amido Black 10B
7. The digital photography was conducted with a Phase One digital back on a Hasselblad camera body. The
digital back has a silicon CCD and the manufacturer has removed its IR filter. The Phase One detector is
sensitive up to 1.1 microns into the IR spectrum.

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