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Natural and Synthetic Colorants in Early Twentieth Century Russian Art Problems of Transition and Coexistence Evangelia A. Varella Aristotle University of Thessaloniki, Greece

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Natural and Synthetic Colorants in Early Twentieth Century Russian Art

Problems of Transition and Coexistence

Evangelia A. Varella

Aristotle University of Thessaloniki, Greece

Introduction

colour is the thingwithout which the world would not be possible

Works of art, exhibited or stored, are susceptible to environmental factors, and alterations occur with the passage of time. To achieve a better and more effective preservation, the behaviour of all materials involved should be clarified.

The complex artistic patrimony of early twentieth century Russian art is amalgamating occidental modernist tendencies with Byzantine expertise, Mongol aesthetic suggestions, and folkloric proposals.

Monochromatic approaches are an outmost target, and hue is acquiring primordial importance, while brilliance and intensity are subjected to eager technical experimentations.

Painting palettes of this controversial period represent an effective model for examining the influence of environmental factors and historical processes to the chromatic profile originally sought by the artist; and for confronting preservation problems created by the coexistence of traditional and modern synthetic colorants.

The Role of Orthodox Iconography and Folkloric Art

Colorants used in Russian icon painting are combining Byzantine tradition to Central Asian proposals, and Renaissance influences.

Recipe collections compiled by local masters are already circulating in the 1400's, while antique and mediaeval treatises are systematically translated from the early seventeenth century on.

Describing sophisticated lake preparations, recording on imported products, adjusting raw materials to indigenous possibilities, experimenting with the binding media – the manuscripts are clearly documenting of a long established craftsmanship.

Hand-coloured folk prints and polychrome wooden artefacts representing all traditions blooming in the immense country, are in general following Orthodox aesthetic principles and technical expertise.

The mineral palette embraces crude and burnt Sienna and umbra earths; baryte, zinc white, lithopone, ceruse; natural cinnabar and vermilion, red lead; Pozzuoli earth, several ochres – haematite, red bole, caput mortuum, Pompei red, and later Mars products; orpiment, massicot, Naples yellow, antimony cinnabar; iron chlorides, silicates and phosphates; lazurite, ultramarine; and a great variety of natural and artificial copper compounds – carbonates e.g. azurite and malachite, chlorides e.g. atacamite, sulphates, nitrates, sulphocarbonates, arsenates, silicates e.g. Egyptian blue, phosphates e.g. pseudomalachite, acetates, e.g. verdigris.

Although relatively rare, colouring lakes are traced as precious counterparts to inorganic pigments. Scale insects, red sandalwood, Brazil wood, madder, dyer’s bugloss, safflower; saffron, Persian berries, Indian yellow; tall cinquefoil; copper resinate; indigo or woad, and carbon black, are largely utilized in pure form or as ingredients of manifold composites.

In the late nineteenth century low cost synthetic colouring compounds are straightforwardly introduced in the traditional painting palette. More often are encountered chrome yellow, and Prussian blue; alizarin, Hansa yellow, and fuchsine.

Modernist Occidental Influences

At the same time, Russian artist are taking modernist colour perception into serious consideration. Impressionist and symbolist European masters are by the turn of the century satisfactorily represented in the Shchukin and Morozov collections, while the First Golden Fleece Salon is leading to a solid implementation of expressionist and cubist concepts.

At a scientific level, innovative circles are well acquainted with the approach developed in Colour Science, a fundamental treatise authored by W. Ostwald and translated in Russian in 1926. According to the essay, primary complementary colour pairs are red/sea green and yellow/ultramarine blue; furthermore orange/turquoise blue and purple/leaf green.

Ivan Kliun is an enthusiastic adherent to the theory; while Boris and Maria Ender are revising the inherent assumptions by recapitulating the experiments on colour pursued in the Petrograd/Leningrad State Institute of Artistic Culture (GinKhuK).

Following in his line of thought the Theory of Colours conceived by J.W. von Goethe, while consenting to the Newtonian reality of tonal priorities, V. Kandinsky – later head of the Moscow Institute of Artistic Culture (InKhuK) –is indirectly reintroducing the ancient concept of tetrachromy, by parenting yellow to the triangle, and materializing blue in the circle.

Avant-Garde Colours and Colorants

Individual avant-garde paintings are accurately reflecting the contradictory historical processes in early twentieth century Russia.

During the ancien régime industrial pigments are ordered to the main German, French and British suppliers; or locally produced by Central European and indigenous firms. By the turn of the century Dosekin is the most renowned relevant Russian company.

In post-revolutionary times materials are frequently deficient or mediocre, even though ingenious procedures are trying to meet the requirements.

the material we are working with are the colorants, and with it alone we create a real new world

we apply colours in practice not, for example, as the reflex of yellow on blue, but as an aggregate of greens of greater or lesser density

an artist uses paints, and paints are never of a pure colour; even cobalt blue differs from a pure blue passed through a prism

the question is if it is legitimate to do away altogether with infinite combinations, which distinguish cadmium yellow from cobalt violet; if it is permissible to draw the boundaries as closed as they are placed by the paint manufacturers

basic colours and colorants are red, black, emerald green, white, and cobalt blue; and complementary ones ultramarine and rarely citron yellow, and madder lake pink … pure cobalt is a dangerous hue … scarlet cinnabar is falling into red lead, or rather pure red lead, cobalt and white

cinnabar and madder, Saturn and English red are favoured tonalities … cobalt green is hard; chrome green, ultramarine blue and madder lake red smooth; emerald green is a bad colour

we create surfaces of hardened lava streams of vermilion, black red crepe varnish, and sky-blue cobalt

yellow is prepared with bleached umbra and red cadmium; dark olive green with umbra, orange cadmium and emerald green; pinkish brown with red cadmium, umbra and white; brown with natural umbra, white and light blue cobalt; and cold brownish red with natural lake umbra, blue cobalt and white

Genuine and Current Chromatic Profile

Russian avant-garde artists were often forced by circumstances to use low quality materials, while the compatibility of traditional and novel pigments was not always well comprehended.

Particularly susceptible to injuries were paintings on paper, since cellulose undergoes natural ageing and decomposes, and can further interact with the actual paint layers, causing denaturation in components of both.

The Stalinist era was drastically rejecting modernist attitudes, and numerous precious works were stocked up in an inefficient way. Consequently the authenticity of their appearance is rather questionable.

The physicochemical research is proceeding by colorimetric and spectroscopic analysis of samples deriving from artificially aged experimental tables, prepared as watercolour and gouache layers on paper ground devoid of preparation. Respective binding media are gum Arabic or gum Arabic and chalk.

Comparison is made with authentic paintings belonging to the Costakis Collection, State Museum for Contemporary Art, Thessaloniki.

The colorants studied are red lead, orpiment and realgar, chrome yellow, verdigris, ultramarine blue, Prussian blue, Mars black; and combinations of orpiment and ultramarine blue, or chrome yellow and Prussian blue. Furthermore carmine lake, Brazil wood, madder and alizarin red, Indian yellow, indigo, van Dyck brown, carbon black; Hansa yellow, and fuchsine.

Recent interventions are faced with the study of quinacridone magenta red, as well as phtalocyanine greens or blues.

A systematic comparative review of all colorimetric, and spectroscopic data permits evaluating the colorants as to compatibility and stability towards extrinsic factors, and is proposing degradation routes at a molecular level, with the intention of contributing to the physicochemical elucidation and appropriate preservation of early twentieth century polychrome works of art.

The experimental tables were subjected for a total time of three months to the influence of moist heat (90oC, 60% relative humidity), and the influence of ultraviolet radiation(30oC, 50% relative humidity).

Colour measurements were performed during the accelerated ageing, and changes expressed using the colour space CIE 1976 (L*a*b*). The surface of both untreated and aged paint layers was as well microscopically observed.

In order to determine the degree, in which chemical and molecular alterations are related to colour changes, micro Raman and FT infrared spectra of paint layers before and after ultraviolet exposure were recorded.

0 20 40 60 800

10

20

30

40

50

60

0 20 40 60 800

10

20

30

40

50

60

chrome yellow orpiment red lead prussian blue ultramarine verdigris mars black

∆Ε∆Ε ∆Ε∆Ε∗∗ ∗∗

accelerated ageing, days

∆Ε∆Ε ∆Ε∆Ε∗∗ ∗∗

accelerated ageing, days

ΔΕ* Changes of Watercolour and Gouache Paint Layers – Inorganic Colorants

90οC, 60% Relative Humidity

ΔΕ* Changes of Watercolour and Gouache Paint Layers– Inorganic Colorants

0 20 40 60 800

10

20

30

0 20 40 60 800

10

20

30

40 chrome yelloworpiment red lead

∆Ε∆Ε ∆Ε∆Ε∗∗ ∗∗

accelerated ageing, days

prussian blueultramarine verdigris mars black

∆Ε∆Ε ∆Ε∆Ε∗∗ ∗∗

accelerated ageing, days

Ultraviolet Radiation, 30οC, 50% Relative Humidity

Red Lead Pb3O4

When exposed to ultraviolet radiation, paint layers displayed a remarkable decrease in brilliance, redness and yellowness. The alteration occurred in slow rate during the first days, had a sharp increase in the middle of the procedure, and was then led to a plateau. It is apparently due to partial transformation to orange yellow litharge –tetragonal PbO.

∆L* = -6.7∆a* = -3.5∆b* = -7.7∆Ε* = 10.8

∆L* = -8.0∆a* = -6.3∆b* = -9.8∆Ε* = 14.1

90οC, 60% Relative Humidity

400 500 600 700

0

20

40

60

80

100

0 days 10 days 90 days

Pb3O

4, watercolour

Ref

lect

ance

%

wavelength (nm)

400 500 600 700

0

20

40

60

80

100

0 days 10 days 90 days

Pb3O

4, gouache

Ref

lect

ance

%

wavelength (nm)

Red Lead

400 500 600 7000

20

40

60

80

100

0 days 30 days 90 days

Pb3O

4, watercolour

Ref

lect

ance

%

wavelength (nm)

400 500 600 7000

20

40

60

80

100

0 days 30 days 90 days

Pb3O

4, gouache

Ref

lect

ance

%

wavelength (nm)

∆L* = -5.1∆a* = -8.3∆b* = -8.6∆Ε* = 13.0

∆L* = -10.3∆a* = -16.5∆b* = -13.1∆Ε* = 23.5

Ultraviolet Radiation, 30οC, 50% Relative Humidity

Red Lead

Raman Spectra of Untreated and Artificially Aged Red Lead Paint Layers[676.4nm, 0.3mW; Litharge Peaks Indicated with an Asterisk]

200 400 600

140 160

280 320 360

200 400 600

90 days

20 days

0 days

Raman shift (cm-1)

Raman shift (cm-1)

Pb3O

4 gouache

*

**

Inte

nsi

ty (

a.u

.)

Pb3O

4 watercolour

0 days

20 days

90 days

140 160

*

*

Ultraviolet Radiation, 30οC, 50% Relative Humidity

Orpiment As2S3

Ultraviolet radiated layers displayed a gradual decrease in redness and yellowness, and an increase in brilliance.

The untreated pigment contains realgar – α-As4S4, which in the aged layer tends to yield pararealgar and arsenolite –As4O6. Fading of red realgar and simultaneous formation of yellow pararealgar and white arsenolite elucidates the changes in the initial hue. Sensitivity to ultraviolet radiation can be attributed to the biphasic state of the orpiment/realgar pigment, and its distribution in finer particles on the paper.

∆L* = -13.7∆a* = -17.2∆b* = -30.4∆Ε* = 37.6

∆L* = -5.6∆a* = -8.6∆b* = -11.8∆Ε* = 15.7

90οC, 60% Relative Humidity

400 500 600 7000

30

60

90

0 days 10 days 30 days 90 days

As2S

3, watercolour

Ref

lect

ance

%

wavelength (nm)

400 500 600 7000

30

60

90

0 days 10 days 30 days 90 days

As2S

3, gouache

Ref

lect

ance

%

wavelength (nm)

Orpiment

∆L* = 9.3∆a* = -15.1∆b* = -18.9∆Ε* = 26.0

∆L* = 13.2∆a* = -18.6∆b* = -28.0∆Ε* = 36.1

Ultraviolet Radiation, 30οC, 50% Relative Humidity

400 500 600 7000

20

40

60

80

100

0 days 30 days 90 days

As2S

3, watercolour

Ref

lect

ance

%

wavelength (nm)

400 500 600 7000

20

40

60

80

100

0 days 30 days 90 days

As2S

3, gouache

Ref

lect

ance

%

wavelength (nm)

Orpiment

Raman Spectra of Untreated and Artificially Aged Orpiment Paint Layers[676.4nm, 0.3mW; Orpiment Peaks Indicated with an Asterisk]

90οC, 60% Relative Humidity

150 225 300 375 450 150 225 300 375 450

As2S

3, watercolour

Inte

nsi

ty (

a.u

.)

Raman shift (cm-1)

0 days

10 days

90 days, As2S

3

90 days, As4S

4

* ** * * * * ***

90 days

10 days

0 days

As2S

3, gouache

Raman shift (cm-1)

Raman Spectra of Untreated and Artificially Aged Orpiment Paint Layers[676.4nm, 0.3mW; Realgar Peaks Indicated with an r/Pararealgar Peaks with a p/ Arsenolite Peaks with an a]

Ultraviolet Radiation, 30οC, 50% Relative Humidity

150 225 300 375 150 225 300 375

Inte

nsi

ty (

a.u

.)

Raman shift (cm-1)

As2S

3, watercolour

0 days

90 days

o p

pp

r

pao

o oo

o

o

r r rrr

r

a

rr

po

p

Raman shift (cm-1)

As2S

3, gouache

op

pp

r

p

0 days

90 days

oo o

o

o

o

o

p

r r r rr

rr

a

a p

r

Verdigris Cu(CH3COO)2.H2OWhen watercolour layers are exposed to moist heat, tenorite – CuO is formed. Reduction to cuprite – Cu2O is stimulated by the reducing sugars of gum Arabic, and accelerated by ultraviolet radiation.

Cuprite formation is taking place to a much smaller extent in the gouache layer; given that calcium is acting as an inhibitor in the reaction of copper with the carbohydrate units of gum Arabic, the presence of chalk could be credited with the relative stability of gouache.

90οC, 60% Relative Humidity

400 500 600 700

0

5

10

15

20

25

30

35

40

400 500 600 7000

10

20

30

40

50

0d 25d

verdigris, watercolour

90oC, 60% RH

Ref

lect

ance

%

wavelength (nm)

0d 25d

verdigris, gouache

90oC, 60% RH

wavelength (nm)

∆L* = -17.9∆a* = 47.1∆b* = 15.8∆Ε* = 52.8

∆L* = -25.1∆a* = 42.8∆b* = 19.5∆Ε* = 53.3

Verdigris

Ultraviolet Radiation, 30οC, 50% Relative Humidity

∆L* = -0.3∆a* = 20.8∆b* = 18.4∆Ε* = 27.8

∆L* = 6.2∆a* = 14.8∆b* = 15.4∆Ε* = 22.2

400 500 600 7000

10

20

30

400 500 600 7000

10

20

30

40

50verdigris, watercolour

0d 5d 20d 90d

Ref

lect

ance

%

wavelength (nm)

verdigris, gouache

0d 5d 20d 90d

wavelength (nm)

Verdigris

Raman Spectra of Untreated and Artificially Aged Verdigris Paint Layers[488nm, 0.25mW; Chalk Peaks Indicated with a c]

90οC, 60% Relative Humidity

200 400 600 800 200 400 600 800

verdigris, watercolour

Inte

nsi

ty (

a.u

.)

Raman shift (cm-1)

x 3622284

331

0 days

25 days

verdigris, gouache

Raman shift (cm-1)

x 3

622287

334

0 days

25 days

c

c

Raman Spectra of Untreated and Artificially Aged Verdigris Paint Layers[488nm, 0.25mW; Cuprite Peaks Indicated with an Asterisk; Chalk Peaks with a c]

Ultraviolet Radiation, 30οC, 50% Relative Humidity

200 400 600 800

*

Inte

nsi

ty (

a.u

.)

Raman shift (cm-1)

0 days

90 days

verdigris watercolour

***

300 600 900

*

0 days

90 days

Raman shift (cm-1)

verdigris gouache

*

c

c

Prussian Blue Fe4[Fe(CN)6]3

Ultraviolet radiated layers demonstrated an initial raising, a subsequent decline, and a final restitution of brilliance values. Raman spectra recorded equally an initial shift of the cyan group to lower frequencies, followed by broadening.

Reduction to Berlin white – K2Fe[Fe(CN)6] is probably taking place, stimulated by the reducing sugars of gum Arabic, and accelerated by ultraviolet radiation. Restitution could be based on the inhibition of any further reduction, as gum Arabic is decomposing. Berlin white is hence partly re-oxidised to Prussian blue.

Ultraviolet Radiation, 30οC, 50% Relative Humidity

0 20 40 60 800

2

4

6

8

10

12

watercolour gouache

UV, 30OC, 50%RH

∆Ε∆Ε ∆Ε∆Ε∗∗ ∗∗

accelerated ageing, days

400 500 600 700

2

4

6

8

10

0d 10d 50d 70d 90d

Fe4[Fe(CN)

6]3, gouache

wavelength (nm)

Ref

lect

ance

%

Prussian Blue

Raman Shifts of the Cyanide Group Stretch Peaks in Prussian Blue During Accelerated Ageing [76.4nm, 0.1mW]

Ultraviolet Radiation, 30οC, 50% Relative Humidity

0 20 40 60 80

2092

2094

2152

2154

2156

0 20 40 60 80

2092

2094

2152

2154

2156

accelerated ageing, days

gouache watercolour

Ram

an s

hif

t (c

m-1

)

accelerated ageing, days

ΔΕ* Changes of Watercolour and Gouache Paint Layers – Organic Colorants

90οC, 60% Relative Humidity

0 20 40 60 80 1000

4

8

12

16

20

24

fuchsin Indian yellow Hansa yellow magenta phthaloblue phthalogreen

alizarin carmine brazilwood indigo van Dyck brown

∆Ε∆Ε ∆Ε∆Ε∗∗ ∗∗

accelerated ageing, days0 20 40 60 80 100

0

4

8

12

16

20

24

∆Ε∆Ε ∆Ε∆Ε∗∗ ∗∗

accelerated ageing, days

ΔΕ* Changes of Watercolour and Gouache Paint Layers – Organic Colorants

Ultraviolet Radiation, 30οC, 50% Relative Humidity

0 20 40 60 80 1000

4

8

12

16

phthalogreen

alizarin carmine brazilwood indigo van Dyck brown

∆Ε∆Ε ∆Ε∆Ε∗∗ ∗∗

accelerated ageing, days0 20 40 60 80 100

0

4

8

12

16

fuchsin Indian yellow Hansa yellow magenta phthaloblue

∆Ε∆Ε ∆Ε∆Ε∗∗ ∗∗

accelerated ageing, days

Carmine LakeColour alterations observed in ultraviolet radiated carmine layers are due to partial loss of the lake complex structure, as well as to crack formation on the surface.

In the infrared spectra, a destabilization of the complex, in which the alum salt is linked through the carbonyl group, could be detected.

Carmine Lake

90οC, 60% Relative Humidity

∆L* = -2.3∆a* = -7.2∆b* = -3.8∆Ε* = 8.5

∆L* = -1.5∆a* = -7.2∆b* = -3.9∆Ε* = 8.3

400 500 600 700-20

-16

-12

-8

-4

0

5d 90d

∆∆ ∆∆R %

wavelength (nm)

watercolour

400 500 600 700

-16

-12

-8

-4

0

5d 90d

∆∆ ∆∆R %

wavelength (nm)

gouache

Carmine Lake

Ultraviolet Radiation, 30οC, 50% Relative Humidity

∆L* = -2.6∆a* = -4.8∆b* = -3.5∆Ε* = 6.5

∆L* = 7.9∆a* = -8.1∆b* = -8.8∆Ε* = 14.4

400 500 600 700

-8

-6

-4

-2

0

45d 90d

∆∆ ∆∆R %

wavelength (nm)

watercolour

400 500 600 7001

2

3

4

5

6

45d 90d

∆∆ ∆∆R %

wavelength (nm)

gouache

Carmine Lake

FT-IR Reflectance Spectra of Carmine Lake Layers before and after Ageing

Ultraviolet Radiation, 30οC, 50% Relative Humidity

2100 1800 1500 1200 9000,0

0,5

1,0

Ku

bel

ka-M

un

k u

nit

s

0d 90d

carmine, watercolour

Ku

bel

ka-M

un

k u

nit

s

2100 1800 1500 1200 9000

2

4

0d 90d

wavenumber,cm-1

carmine, gouache

4000 3500 3000 2500 2000 1500 10000

1

2

Ku

bel

ka-M

un

k u

nit

s

wavenumber,cm-1

4000 3500 3000 2500 2000 1500 10000

1

2

3

4

5

6

7

Ku

bel

ka-M

un

k u

nit

s

wavenumber,cm-1

Brazil WoodUnder ultraviolet radiation, main parameter contributing to the total colour difference is L*, confirming that the fugitive behaviour of the dye is playing the predominant role in colour change.

The infrared spectra are implying that even a 350 nm radiation is sufficient for inducing oxidation of phenolic brazilin to aromatic carboxylic brazilein.

A small rise in brilliance under the effect of moist heat is pointing at a dye loss on the paper substrate.

Ultraviolet Radiation, 30οC, 50% Relative Humidity

∆L* = 6.4∆a* = -0.7∆b* = -0.8∆Ε* = 6.5

∆L* = 11.1∆a* = 0.7∆b* = 0.5∆Ε* = 11.1

400 500 600 7006

8

10

12

14

16

18

20

0 days 90 days

brazilwood, watercolour

Ref

lect

ance

%

wavelength (nm)400 500 600 700

0

4

8

12

16

20

24

28

0 days 90 days

brazilwood, gouache

Ref

lect

ance

%

wavelength (nm)

Brazil Wood

FT-IR Reflectance Spectra of Brazil Wood Layers before and after Ageing

Ultraviolet Radiation, 30οC, 50% Relative Humidity

2000 1750 1500 1250 1000 750

0

4

8

12

16

Ku

bel

ka-M

un

k u

nit

s

0d 90d

watercolour

Ku

bel

ka-M

un

k u

nit

s

2000 1500 1000

0

4

8

12

16

0d 90d

wavenumber,cm-1

gouache

4000 3500 3000 2500 2000 1500 1000

0

4

8

12

16

Ku

belk

a-M

unk

uni

ts

wavenumber,cm-1

4000 3500 3000 2500 2000 1500 1000

0

4

8

12

16

Ku

belk

a-M

unk

unit

s

wavenumber,cm-1

AlizarinColour fading, observed in alizarin layers subjected to moist heat ageing, is due to alterations in the intramolecular hydrogen bonding between the carbonyl and the hydroxyl group, as well as to high crack formation on the surface.

90οC, 60% Relative Humidity

∆L* = 0.3∆a* = -6.2∆b* = -5.2∆Ε* = 8.0

∆L* = -3.6∆a* = -7.7∆b* = -10.2∆Ε* = 13.3

400 500 600 700-4

-3

-2

-1

0

1

2

10 days 90 days

∆∆ ∆∆R %

wavelength (nm)

watercolour

400 500 600 700

-6

-4

-2

0

2

10days 90days

∆∆ ∆∆R %

wavelength (nm)

gouache

Alizarine

FT-IR Reflectance Spectra of Alizarin Layers before and after Ageing

90οC, 60% Relative Humidity

4000 3500 3000 2500 2000 1500 1000

0

2

4

6

8

10

12

14

4000 3500 3000 2500 2000 1500 1000

0

2

4

6

8

10

12

14

4000 3500 3000 2500 2000 1500 1000

0

2

4

6

8

10

12

14

0d 90d

Ku

bel

ka-M

un

k u

nit

s

wavenumber,cm-1

alizarin

0d 90d

wavenumber,cm-1

alizarin, watercolour

0d 90d

wavenumber,cm-1

alizarin, gouache

Indian YellowThe colorant was fairly susceptible to moist heat ageing. On the surface of both watercolour and gouache layers, formation of dark areas is explaining the decrease of all colour parameters.

The physical nature of the chromatic alteration –deterioration of the smooth surface, changes in particle aggregation, crack formation – was proven by the lack of differentiation in the infrared spectra.

90οC, 60% Relative Humidity

∆L* = -3.0∆a* = -5.6∆b* = -4.8∆Ε* = 8.0

400 500 600 7000

10

20

30

0 days 30 days 90 days

watercolour

Ref

lect

ance

%

wavelength (nm)

Indian Yellow

Hansa yellow PY3Under high temperature and humidity, important decreases in both brilliance and yellowness are observed. A warm and moist environment is causing extended crack formation, responsible for reducing reflectance values.

Lessening of yellowness may be due to gradual sublimation of the colouring agent.

90οC, 60% Relative Humidity

∆L* = -8.7∆a* = -0.4∆b* = -19.2∆Ε* = 21.1

400 500 600 700

0

20

40

60

80

100

0 days 45 days 90 days

watercolour

Ref

lect

ance

%

wavelength (nm)

Hansa Yellow

FuchsineAs a solid, fuchsine forms green-yellow crystals, turning to purple when dissolved in water. Exposure in ultraviolet light caused an immediate substantial decrease of b values in both watercolour and gouache layers.

Infrared spectra of ultraviolet radiated layers recorded amino group shifts due to the intramolecular charge transfer caused by ultraviolet excitation.

An increase in brilliance, observed after forty days of ageing, is justified on the basis of the more fugitive dye monomer. On the paint layer surface the paper was at occasions totally revealed.

The increase in brilliance and yellowness is related to the formation of bright yellow areas, probably due to aggregation of dye crystallites and the improvement of their reflecting surface. Further ageing induced intense crack formation, and subsequent re-darkening of the surface.

Ultraviolet radiation, 30οC, 50% Relative Humidity

∆L* = -4.5∆a* = -0.4∆b* = -14.1∆Ε* = 14.8

∆L* = 3.2∆a* = 0.3∆b* = -14.0∆Ε* = 14.4

Fuchsine

400 500 600 7000

4

8

12

16

20

0 days 90 days

fuchsin, watercolour

Ref

lect

ance

%

wavelength (nm)

400 500 600 7000

4

8

12

16

20

24

0 days 90 days

fuchsin, gouache

Ref

lect

ance

%

wavelength (nm)

FT-IR Reflectance Spectra of Fuchsine Layers before and after Ageing

Ultraviolet Radiation, 30οC, 50% Relative Humidity

4000 3500 3000 2500 2000 1500 1000

0

6

12

4000 3500 3000 2500 2000 1500 1000

0

6

12

0d 90d

fuchsin, watercolour

Ku

bel

ka-M

un

k u

nit

s

wavenumber,cm-1

0d 90d

wavenumber,cm-1

fuchsin, gouache

In general, colouring agents – with the exception of alizarin, Indian yellow, and Hansa yellow – were stronger influenced by ultraviolet light than by high temperature combined to humidity.

Red lead, orpiment, verdigris, Prussian blue, carmine lake, and Brazil wood proved more sensitive; while chrome yellow, ultramarine blue – 3Na2O.3Al2O3.6SiO2.Na2S, alizarin, Indian yellow, Hansa yellow, and fuchsine exhibited a better stability.

Mars black – Fe3O4, indigo, van Dyck brown; quinacridone magenta red PR122, and phtalocyanine green or blue were hardly affected.

phtalocyanine green and blue

quinacridone magenta red PR122

The higher light sensitivity of gouache layers might be attributed to the lower concentration and smaller aggregation of pigment particles, since they are interpolating with chalk entities.

The comparative review of all data permits regenerating certain features of the chromatic profile, as originally created by the artist; is evaluating the colorants as to compatibility and stability towards extrinsic factors; and is proposing degradation routes at a molecular level.

The experimental tables were subjected to the ageing tests in a Voetsch VC0018 climatic chamber. They were exposed to Philips Cleo 20W fluorescence tubes, which emit highly concentrated ultraviolet radiation in the 300-400 nm range, peaking at 350nm. The samples were placed at a distance of 2 cm from the radiation source.

A Miniscan XE Plus spectrophotometer (HunterLab) was used for colour measurements during the accelerated ageing. The surface was studied under an Olympus Bx60 optical microscope with a JVC TK-C1381 camera and Leica MW Software. The total colour difference ∆Ε* between the sample prior to light exposure and at each measurement during the ageing was calculated according

to the equation: ∆Ε*= {(∆L*)2 + (∆a*)2 + (∆b*)2 }1/2.

Micro-Raman spectra were recorded using a triple grating spectrometer (Dilor XY) equipped with a CCD liquid-nitrogen cooled detector system. The blue (488 nm) line of an Ar ion laser and the red line (676.4 nm) of a Kr ion laser were used for excitation and the spectral resolution of the system was ~3 cm-1. The laser was focused on the sample through the system’s microscope equipped with a standard objective lens 100x. The relevant power was kept at 0.1 - 0.3mW, in order to avoid damaging the underlying samples.

FT-Infrared spectra were recorded on a Perkin Elmer Spectrum GX II spectrometer equipped with a MCT detector. The spectra were collected in reflectance mode in the range of 4000-700 cm-

1, with a resolution of 4 cm-1, an aperture of 100x100 µm, and 300 scans per measurement. Four spectra from different areas of each sample were recorded and the average spectrum was calculated.

As a conclusion, colour alterations due to environmental factors have been elucidated; and degradation routes have been proposed, with the intention of assisting museum conservators in every concrete case related to the broad spectrum of pigments, either actually studied or belonging to chemically related compound groups.

Physicochemical Investigation of Avant-Garde Paintings

The survey encompasses a series of samples taken from twenty-two watercolour and gouache paintings on paper, belonging to the Costakis Collection in the State Museum for Contemporary Art, Thessaloniki.

In an attempt to represent a significant number of art historical tendencies and theoretical concepts, as well as to consider a large variety of hues, the selection focused on Boris, Maria, Xenia and Yuri Ender, Ivan Kliun, Ivan Kudriashev, Salomon Nikritin, Konstantin Vialov, Alexander Volkov, and possibly Liubov Popova.

Artist Inv. Number Numberof Samples

Colourof Samples

B. Ender C473 3 pale green/dark green/blue

M. Ender C429/AB625 2 scarlet red/dark red

X. Ender 173.80/Α 1 black

175.80 1 reddish violet

392.81 1 green

C453.549 1 blue

C454 3 red/pale green/blue

34.78 3 brownish red/scarlet red/blue

Y. Ender C259 1 azure

C472 2 reddish green/leaf green

I. Kliun AB306/802.79 1 bluish purple

AB326 1 green

C555 1 fuchsia red

C559 1 dark bluish purple

C446 1 brown

I. Kudriashev AB416/C501 1 green

AB739 1 black/white

S. Nikritin 8-C9 2 red/black [ink]

9-C219 1 grey

K. Vialov 227.80 3 green/blue/black

A. Volkov 281 14 red/pink/orange/greenish yellow/citron yellow/dark yellow/pale green/dark green/pale azure/azure/dark azure/turquoise/ultramarine blue/dark blue

[L. Popova] C717 9 red/greenish pink/pale green/leaf green/dark green/ azure/turquoise/ultramarine blue/dark blue

List of Paintings [Costakis Collection, State Museum for Contemporary Art, Thessaloniki]

Colouring compounds identified include chalk, zinc white, vermilion, red ochre/Mars red, red lead; carmine lake, madder/alizarin; yellow ochre/Mars yellow, chrome yellow, and zinc yellow; emerald green, ultramarine blue, Prussian blue, and carbon black; as well as various well-established or unconfirmed mixtures.

Zinc white acts as a prevailing white colorant, being at the same time an excellent gouache filler, along with chalk.

Chalk Zinc White

Vermilion Red Ochre/Mars Red

Red Lead Carmine Madder/Alizarin

B. Ender

M. Ender *

X. Ender * *

Y. Ender *

I. Kliun * * * *

I. Kudriashev *

S. Nikritin * * *

K. Vialov

A. Volkov * * *

[L. Popova] * *

Yellow Ochre/ Mars Yellow

Chrome Yellow

Zink Yellow

Chrome Green

Emerald Green

Ultramarine Blue

Prussian Blue

Carbon Black

B. Ender * *

M. Ender

X. Ender *a * * *

Y. Ender * * *

I. Kliun * * * * *

I. Kudriashev * * *

S. Nikritin *

K. Vialov * * *a

A. Volkov * * * *

[L. Popova] *a *

Distribution of Colorants by Painter [Sporadic Grains Indicated with an a]

Raman Spectra of Samples Identified as Vermilion and Red Lead [676.4nm, 0.3mW]

Vermilion HgS Red Lead Pb3O4

200 250 300 350 400

Raman shift (cm-1)

Inte

nsi

ty (

a.u

)

254

285 34

3

M. Ender, Inv.Nr. C429/AB625 A. Volkov, Inv.Nr. 281

200 300 400 500

STANDARD

Inte

nsi

ty (

a.u

.)

Raman shift (cm-1)

549

391

313

22415

212

2

SAMPLE

Raman Spectra of Samples Identified as Mars Red [676.4nm, 0.3mW]

Mars Red Fe2O3

200 300 400 500 600 700

Inte

nsi

ty (

a.u

.)

Raman shift (cm-1)

227 29

3

411

614

200 300 400 500 600 700

Inte

nsi

ty (

a.u

.)

Raman shift (cm-1)

226

293

410

613

1050 1100 1150

Raman shift (cm-1)

1087

I. Kliun, Inv.Nr. C559 S. Nikritin, Inv.Nr. 8-C9

a b

Raman and FT-IR Reflectance Spectra of a Sample Identified as Alizarin [488nm, 0.3mW]

Alizarin

X. Ender, Inv. Nr. C454

1100 1200 1300 1400 1500 1600 1700

Raman shift (cm-1)

Inte

nsi

ty (

a.u

) 1299

1326

1355

1472

1639

Raman Spectra of Samples Identified as Chrome Yellow and Emerald Green [676.4nm, 0.3mW]

Chrome Yellow PbCrO4 Emerald Green Cu(C2H3O2)2.3Cu(AsO2)2

A. Volkov, Inv.Nr. 281 B. Ender, Inv.Nr. C473

300 400 700 800 900 10001100

840

400

377

358

338

325

Inte

nsi

ty (

a.u

.)

Raman shift (cm-1)

282

1087

STANDARD

SAMPLE

SAMPLE

100 200 300 400 500 600 700 800 900 1000

Raman shift (cm-1)

Inte

nsi

ty (

a.u

)12

015

317

321

524

329

332

4 370

432 53

9

948

760

835

Raman Spectra of Samples Identified as Ultramarine Blue [676.4nm, 0.3mW]

Ultramarine Blue 3Na2O.3Al2O3.6SiO2.Na2S

K. Vialov, Inv.Nr. 227.80 A. Volkov, Inv.Nr. 281

450 600 750 900 1050

Inte

nsi

ty (

a.u

.)

Raman shift (cm-1)

545

584 1091

200 400 600 800 1000

Inte

nsi

ty (

a.u

.)

Raman shift (cm-1)26

3

547

584 80

5 1096

Raman Spectra of Samples Identified as Prussian Blue [676.4nm, 0.3mW]

Prussian Blue Fe4[Fe(CN)6]3

B. Ender, Inv.Nr. C473 X. Ender, Inv.Nr. C454

2050 2100 2150 2200

Raman shift (cm-1)

Inte

nsi

ty (

a.u

)

SAMPLE

SAMPLE

STANDARD

2093

2155

2050 2100 2150 2200

Raman shift (cm-1)

Inte

nsi

ty (

a.u

)

2093

2154

As a rule, a mixture of blue and yellow pigments – usually chrome yellow and Prussian blue – is credited with the creation of green areas. In several cases zinc yellow is added to Prussian blue, or yellow ochre to ultramarine blue.

Purple tints are habitually due to ultramarine blue mixed with vermilion, or with carmine lake and carbon black.

Carbon black is yielding brown with Mars red, and grey with zinc white.

Red Orange Green Purple Brown

X. Ender Mars yellow, chrome yellow,Prussian blue

vermilion,Prussian blue

Y. Ender zinc yellow, Prussian blue

zinc yellow,ultramarine,vermilion

I. Kliun chrome yellow, Prussian blue

red ochre,ultramarine

carmine lake, ultramarine,zinc white

red ochre,ultramarine,carbon black

I. Kudriashev yellow ochre, ultramarine

K. Vialov yellow ochre,ultramarine

yellow ochre, Prussian blue

A. Volkov red lead, chrome yellow

chrome yellow, Prussian blue

chrome yellow,Prussian blue

[L. Popova] red lead, madder lake

yellow ochre,carbon black

Distribution of Composite Colorants by Painter

Raman Spectra of a Sample Identified as Chrome Green [Chrome Yellow Peaks Indicated with a c, Prussian Blue Peaks with a p]; and of the Yellow Component of a Green Sample, Identified as Chrome Zinc Yellow [676.4nm, 0.3mW]

Green Tints

I. Kliun, Inv.Nr. AB326

250 500 750 2100 2200

Inte

nsi

ty (

a.u

.)

Raman shift (cm-1)

c

c

p

p

150 300 450 600 750 900 1050

Raman shift (cm-1)

Inte

nsi

ty (

a.u

)

346

774

870

891

940

ZnCrO4

Y. Ender, Inv.Nr. C472

Raman Spectra of a Sample Identified as Vermillion and Prussian Blue; and of the Red Component of a Purple Sample, Identified as a Mixture of Carmine and Carbon Black [676.4 nm, 0.3 mW]

Purple Tints

I. Kliun, Inv.Nr. C555 I. Kliun, Inv.Nr. AB306 802.79

400 800 1200

Inte

nsi

ty (

a.u

.)

Raman shift (cm-1)

225

293

411

498

611

25754

5

580

1094

200 300 400

Raman shift (cm-1)

254

284

344

1200 1300 1400 1500 1600

Inte

nsi

ty (

a.u

.)

Raman shift (cm-1)

1231

1259

1325

1395

1491

1595

1659

Raman Spectra of a Sample Identified as Mars Red and Carbon Black; and of a Sample Identified as Zinc White and Carbon Black [676.4 nm, 0.3 mW]

Brown and Grey Tints

I. Kliun, Inv.Nr. C446 I. Kudriashev, Inv.Nr. AB739

200 400 600 1200 1400 1600

Inte

nsi

ty (

a.u

.)

Raman shift (cm-1)

225 29

3

411

498 61

1

1340

1600

80 100 120 420 440 460

Inte

nsi

ty (

a.u

.)

Raman shift (cm-1)

98

437

1300 1400 1500 1600 1700

Raman shift (cm-1)

1371

1586

Systematization, Valorisation & Dissemination of e-Learning Courses in Conservation Science

Lifelong Learning Programme/Erasmus/Virtual Campus

Partners:Aristotle University of Thessaloniki (coordinator)University of Avignon & the Vaucluse Cà Foscari University of Venice Rey Juan Carlos University at Madrid aStyle Linguistic Competence, Vienna S. Mohammed ben Abdellah University of Fez

http://econsc.chem.auth.gr/VirtualCampus

The project addresses virtual mobility in the field of material cultural heritage preservation by organizing specialized course units on conservation science, as well as seminars on concrete diagnostic or safeguarding problems.

It is conceived as a virtual campus offering joint curricula in both lecturing and practicing laboratory work, and enhancing the birth of a common language in problem solving.

Contact Persons:Evangelia A. Varella (Greece) [email protected] Cathy Vielliescazes (France) [email protected] Paolucci (Italy) [email protected] Mariano Fajardo (Spain) [email protected] Benslimane (Morocco) [email protected]

Water Zeller (administrator for linguistic issues) [email protected] Kozaris (ICT administrator) [email protected]

3rd Summer School on Conservation Science

July 19-31, 2008

Thessaloniki, Greece

http://culture.chem.auth.gr/SummerSchool2009(available from 15th of December 2008)