This work aims to investigate the correlation between the painting products used by Picasso to produce four artworks in Barcelona in 1917 and their really conditions. Specifically, a range of crack species and trends was observed in the painted layers. The paintings, kept together in Picasso’s family house until they to be donated to the Museu Picasso in 1970, had far-reaching differences in their condition, even though they current several similarities in the an option of materials, method and in their conservation history. A multi-analytical strategy was embraced to characterise the painted layers by X-ray fluorescence spectroscopy, fibre optic reflectance spectroscopy in the 350–2200 nm range, gas chromatography-mass spectrometry, and Fourier change infrared spectroscopy. The derived results have actually been combined with those from a vault analytical campaign focused ~ above the study of grounds and also canvases the these 4 paintings and also with intuitive examination that the crack to establish hypotheses about the differences in degradation. This an unified overview the non-invasive documentation techniques, chemical analysis and monitorings of the mechanical damage has noted an understanding into the possible contribution every layer might have play in the damage observed in the four canvas paintings.

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Introduction


This research presents results derived by a multi-analytical study on the ingredient of paint layers in 4 paintings developed by Pablo Picasso in Barcelona in 1917, currently belonging come the Museu Picasso, contrasted to a descriptive evaluation on the cracks observed.

The paintings, namely Seated guy (MPB110005; 104 × 54 cm), guy with Fruit bowl (MPB110006; 100 × 70 cm), mrs on an Armchair (MPB110007; 92 × 64 cm), and also Blanquita Suárez (MPB110013; 73 × 47 cm), have actually a range of crack species and patterns in the painted layers. This paper brings with each other the outcomes of a ahead analytical campaign performed on the grounds and also canvases offered by Picasso and the latest examine on the paint movies of the selected paintings in an attempt to burned some irradiate on the relationship between the selection of the materials, setting conditions, fail mechanisms, and also degradation patterns. The key aim was to identify whether differences in the ingredient of the paints might have contributed to the variation in destruction shown by each painting.

The selected paintings were developed during Picasso’s stay in Barcelona (June–November 1917) in a cubist style. In this period, Picasso regularly worked in Rafael Martinez Padilla’s studio. This facet is of utmost relevance. The currently documentation shows that Picasso go not have his very own studio; therefore, he did no re-use any type of canvas (as he commonly did) and also had to acquisition all the paint materials consisting of canvases, brushes, turpentine and oil paints. This could explain the small palette used, minimal to 7 colours (white, black, brown, red, yellow, green and also blue) add to two more colours resulting from their mix (grey and beige). Offered the geometric and colour similarities, these 4 paintings represent a collection within the group of 11 paintings developed in Barcelona in 1917, resulting in this compare study. As soon as Picasso returned to Paris, the paints were save in his family members house until they were donated come the Museu Picasso in Barcelona in 1970, the school that still owns the functions <1,2,3> (Fig. 1). One final facet relevant come the choice of these case studies is that the paintings are placed on the original stretchers and also no evidence of preservation treatments before this donation has been found. In 2016 the museum noticed the should consolidate only one of the paintings, namely sit Man, due to extensive cracking and also fear of repaint loss.


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Woman on an Armchair in ~ Picasso’s family members house. Casa Vilató (Passeig de Gracia, 48, s/d, Barcelona). Fotografia de J. Francès Estorch. Fons Joan Vidal Ventosa, Museu Picasso, Barcelona.


Considering that paints are complex, heterogeneous, multi-layered, and dynamic systems, identify the composition and also material nature of the different layers that a painting is vital in the understanding of degradation processes and products and also their interaction <6, 8>. A previous study by the authors concentrated on the relationship in between the composition and the physical–mechanical properties of paint support materials (canvases and the soil layers) offered by Picasso in the 4 paintings <4>. The results had showed that, in every cases, the artist painted on noodle canvases and applied 2 ground layers. The organic composition of the grounds largely consisted of pet glue, mixed with tiny amounts of drying oils and polysaccharide compounds. In the 4 paintings, the bottom floor layer to be richer in binding media 보다 the top one. In particular, the upper ground great of man with a Fruit bowl was largely composed the a zinc (Zn)-containing compound, whereas the top ground layer in the three other paintings was mostly composed of command white and other materials including calcite. This had probably brought about the slight distinctions in the ton of the four ground layers, varying from grey come orange tinges. The vault work already addressed some hypotheses around the difference in crack fads observed in the paintings (Table 1) charline-picon.comed to the existence of one of two people Zn or command (Pb) in the grounds <7>, the lot of pet glue in soil layers, and the degree of tightness in the canvas weave <4,5,6>.


In this study, a multi-analytical study was carried out to research the colour palette that the 4 paintings, prioritizing the use of non-invasive techniques such together in-situ X-ray fluorescence spectroscopy (XRF) and also fibre optic reflectance spectroscopy (FORS). Moreover, a small number of micro-samples indigenous each painting was analysed through optical microscopy (OM) and also gas chromatography-mass spectrometry (GC–MS). Micro-Fourier change infrared spectroscopy (µ-FTIR) analysis was likewise performed, as soon as there to be a adequate amount of continuing to be sample. In this way, the results derived through element analyses were an unified with the spectroscopic and also chromatographic results, allowing the identification of the palette and also the binding media provided by the artist.


In situ elemental evaluation was carry out non-invasively v portable Elio X-ray fluorescence tools by XGlab X and also Gamma ray Electronics, which has actually been successfully applied on modern and modern paintings <8>. The repaint examination to be performed directly on the surface ar of the areas significant in Fig. 2. The evaluation was lugged out in air, v a sample area the 1 mm diameter, 100 s salvation live-time at 40 kV and 100 μA, using an Rh-target without filtration.


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A small variety of micro-samples from the painted great of the 4 artworks were built up to recognize the inorganic and organic binding media. The samples to be analyzed through micro-Fourier change infrared spectroscopy (µ-FTIR) in attenuated full reflectance (ATR) and also transmittance mode with a Thermo Fisher clinical Nicolet iN10 MX Ultra rapid Motorized stage with MCT Detector. The spectra to be acquired in between 4000 and 600 cm−1, 128 scans, v a resolution of 4 cm−1.

The organic binding media was additionally analysed through GC–MS utilizing an Agilent 6890NGC instrument with a capillary HP-5 (5%-phenyl)-methylpolysiloxane pillar (30 m, 0.25 mm, 0.25 µm), interfaced v an Agilent 5973NetworkMS. The temperature programme was collection from 80 °C to 315 °C, 10 °C/min. The ms was run in FullScan mode (m/z 50–600), 1.9 scans/s. The deliver line was at 280 °C and the resource temperature was 150 °C. Electron ionisation energy was 70 eV. Quantitative GC–MS analysis was performed utilizing nonadecanoic acid as the inner standard. The paint samples were transestherified using (trifluoromethylphenyl)trimethylammonium hydroxide (2.5% in methanol), overnight reaction as explained in <9,10,11>. The following molar ratios in between the most far-reaching fatty acids were calculated: palmitic to stearic acid (P/S), azelaic come palmitic mountain (A/P), oleic come stearic mountain (O/S) and azelaic come suberic acid (A/Sub) ratios, as reported also in . The derived data were contrasted to ahead results acquired by the writer on twenty century artist oil paints as defined in <11,12,13>.

For picture processing, the areas homogeneous in colour to be defined and for each of castle the contour lines were very first processed, trying to boost the differences in between light and dark areas. Then, the photos were desaturated (in grayscale), editing and enhancing the recommendations "black" (0) and also "white" (255) to highlight the cracks.


Table 1 offers an in its entirety description of the crack patterns observed in the 4 paintings. Together mentioned, different deterioration phenomena were observed in the paintings.

Even though every the paintings had actually been save in the unstable atmosphere of the very same house, just the painting Seated male showed such considerable damage. The fact that the cracks were end the whole surface but less pronounce in areas protected through the stretcher bar follow me the edge, argues that the damages was environmentally induced. If this is the case, the interesting question is why the various other three paints do not show the same degree of damage. One explanation may be that the ingredient of materials is different and therefore brought about this paint to be an ext affected by the ambient environment.

In this section, the outcomes for the pigments and also binders of various paints indigenous the 4 paintings are presented. Considering the previous examine of the canvas supports and also ground great <4>, this multi-analytical study is intended to determine the composition and condition of the paint film, and also to investigate if the paint layer could have had actually any affect in the cracks observed in the 4 paintings.

Picasso’s Palette

XRF and FORS are non-invasive, effective, and also rapid methods to recognize the tentative pigment composition <18,19,20>. This section describes all feasible pigments detected in the painted areas and Table 2 gives the results for each particular painting.


XRF evaluation on the four paintings verified that Pb to be the main element in the white painted layers, suggesting the presence of the simple lead (II) carbonate, lead white (2PbCO3·Pb(OH)2). This was additionally confirmed by FORS and also FTIR results (due come the properties IR bands in ~ 1450 nm as well as at approximately 3530,1390 and also 680 cm−1). In some white areas, barium (Ba) was additionally detected, more probably together barite (barium sulphate, BaSO4) used as a filler mixed with lead white. In other white areas, XRF outcomes revealed Zn and Ba, which might be connected with the visibility of lithopone or the visibility of barite and a zinc-based compound. FORS and XRF uncovered lead white likewise in the grey and also beige hues. Moreover, in two of the three beige painted areas, an steel (III) hydroxide-oxide-based colours was determined <21, 22>. Similarly, in the grey areas of 2 paintings, FORS discovered iron oxides. XRF identified reasonably low quantities of silicon (Si) and possibly titanium (Ti) in part grey areas, wherein FORS identified the presence of alumino-silicates, due to the existence of an extremely weak absorption bands in the 1380–1420 nm range that can be related to the an initial overtones the the hydroxyl extending vibration mode. The visibility of titanium can be pertained to impurities of planet pigments <23>.

In one case, mrs on one Armchair, the bluish-grey repaint was tentatively determined by FORS together a mixture of a carbon-based pigment and also ultramarine blue (3Na2O.3Al2O3.6SiO2.2Na2S). This blue pigment to be detected by FTIR as well, because of the peculiar absorptions at approximately 970, 690, 650, and 580 cm−1. Its presence might explain the grey tone of the paint.

Regarding the black color pigments offered in three of the 4 paintings, the visibility of calcium (Ca) and phosphorous (P) is likely connected with the usage of an cream color or bone black pigment (Ca3(PO4)2 + CaCO3 + carbon (C)) as the key black pigment. Moreover, iron-based colours were likewise detected in some of the black areas. It was not possible to perform FTIR analysis to corroborate this finding.

In the red and brown locations analysed, stole (Fe) and also mercury (Hg) to be the main aspects detected through XRF. This indicated a mixture of an steel (III) oxide-based pigment, such together Mars red, and vermillion (both shown by FORS).

Yellow and also green pigments were current only in man with a Fruit Bowl and Blanquita Suarez and mainly contain chromium (Cr). The visibility of Cr in green areas was regarded the viridian colours (Cr2O3.2H2O) as uncovered by FORS. Viridian, more transparent and vivid than the chrome oxide eco-friendly pigment, was likewise used in the time period and was steady (18). Strontium (Sr) and Fe were also detected in guy with a Fruit key in some of the yellow and green areas analysed, describe the existence of strontium yellow (SrCrO4) and iron-based compounds. Commercially, strontium yellow (strontium chromate) was regularly mixed with other pigments, such together Prussian blue (Fe43) <24>.

Blue locations were observed only in Blanquita Suárez. This resulted to contain a mixture of charline-picon.com containing Zn, Zn oxide and/or Zn sulphide, and also a blue pigment. The blue colors was determined as ultramarine blue by FORS and also in previous research study by scanning electron microscopy with power dispersive X-ray spectroscopy (SEM–EDX) ~ above a cross-section native the exact same area the the painting <25>. This detect was likewise corroborated by FTIR analysis. Ultramarine blue was likewise tentatively established by FORS in some of the grey locations of mrs on one Armchair.

Binding media

As reported in Table 2, FTIR and also GCMS evaluation of micro-samples verified that the check paints were bound in lipid media. The IR spectra showed the typical absorptions because of the presence of lipid-based binding media, in details those in ~ 2921, 2850 (stretching–CH2CH3), 1729, 1708 (stretching C = O) and 1166 cm−1 (stretching C-O) <26>.

GCMS results detailed further details around their composition according to the fat acids profile. Table 2 lists the GCMS results and reports the ratios in between azelaic-to-palmitic acid (A/P), oleic-to-stearic acid (O/S) and also palmitic-to-stearic acid (P/S) and also azelaic-to-suberic acid (A/Sub) which are usually used because that the characterisation of dry oils <11, 27,28,29>.

All the analysed paint samples from seated Man, male with a Fruit Bowl, and also Woman on one Armchair were characterised by the typical composition of a polymerised dry oil paint, through saturated mono-saturated fat acids (mirystic acid, lauric acid, palmitic acid, stearic acid), di-fatty mountain (azelaic acid, suberic acid, sebacic acid), and also traces that unsaturated oleic acid <30,31,32>. The calculated A/P ratios to be generally greater than 3 which indicated a high degree of oxidation: azelaic acid, in fact, is the many abundant product created upon oxidation and also polymerisation the unsaturated fat acids present in fresh drying oils. In the exact same way, the O/P ratios to be in all situations lower than 0.1, suggesting that the lipid networks were well polymerised and only very low quantity of unsaturated oleic acid was quiet present. In this sense, the existence of lead-based compounds, detect both in soil layers <4> and also in the pigments from the painted layers (see XRF, FORS and also FTIR results in Table 2), may have actually catalysed the polymerisation and also the oxidation processes.

Although the to know based just on the P/S ratios is no always completely reliable for contemporary and modern oil paints <11, 13,14,15,16,17>, some indications about the type of oils have the right to be provided. The brown paints, having actually P/S ratios worths ranges in between 1.8 and also 1.9, were likely bound in linseed oil. Because that the whites, because of the calculate of P/S ratios and also the to know of particular fatty mountain (arachidic and also behenic acids), safflower and/or sunflower oils and also poppy seed oil were most likely detected in man with a Fruit Bowl and Woman on an Armchair, respectively. These findings concur with details literature reporting that, in general, white and also blue pigments were bound in poppyseed, safflower and also sunflower oils, to stop yellowing occurring in linseed oil during curing <33,34,35>. According to the derived A/Sub ratio <29>, the existence of a pre-heated linseed oil was figured out in sit Man: just in this case, in fact, the A/Sub worth was 1.4, introduce to a pre-treatment by food preparation or boiling the vegetables oil.

The red paint in Blanquita Suárez was bound in linseed oil. The white paint appeared to it is in a mixture the drying-semi-drying oil (safflower and sunflower oils, as viewed for various other white paints) include phthalic acid and also glycerol in a high amount. An explanation for the visibility of this compound has not however been determined: phthalic acid is indeed a an extremely common ecological contaminant and also not necessarily a repaint constituent, but its far-reaching presence can be concerned the usage of an alkyd-based compound. However, this needs further research as alkyd paints were introduced right into the art sector only later on in the 1930s <36,37,38,39,40>.

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Another important factor to consider related to the organic fraction is the detection that carboxylates, also known as metal soaps. In particular, lead soaps to be observed because of the common FTIR absorption peak at roughly 1530 cm−1: these carboxylates had actually likely developed as commodities after the reaction of metal ions (from command white pigment) and the carboxylic mountain after hydrolysis that the fatty acid moieties in the triglycerides of dry oils <41>. The the development of steel carboxylates has solid implications for the preservation of twenty century paintings is well known and, thus, more research is required to monitor eventual conservation problems which can occur in Picasso paintings.