Mihaela Olaru 1 , Bogdana Simionescu 2,3 and Lacramioara Stratulat 3

1. Analysis and structural characterization of pigments and materials used in NicolaeGrigorescu heritage paintings Mihaela Olaru1, Bogdana Simionescu2,3 and Lacramioara Stratulat3 1“Petru Poni” Institute of Macromolecular Chemistry, Iasi, Romania 2“Costin D. Nenitescu” Centre of Organic Chemistry, Bucharest, Romania 3“Moldova” National Museum Complex, Iasi, Romania

2. NicolaeGrigorescu (1838 – 1907) - one of the founders of modern Romanian painting NicolaeGrigorescu Ox cart The Smardan attack Woman on the seashore The little girl with red headscarf "Little peasant girl resting”, the most expensive work traded on the Romanian market Gypsy's head Peasant woman from Muscel Cheerful peasant girl

3. - a multi-technique approach regarding the identification and structural characterization of pigments and materials used by NicolaeGrigorescu in three heritage paintings, i.e., “Old Lady with Basket”, “The Shepherd” and “The Return from Fair” “Old Lady with Basket” “The Shepherd” “The Return from Fair” - X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), Near-infrared spectroscopy (NIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, IR reflectography, UV and optical microscopy Lapis lazuli - a sodic-calcicaluminosilicatesulphate compound with an approx. formula (Na, Ca)8(AlSiO4)6(SO4,S)2), with some of the silicon atoms substituted by sulphur anions - lazurite, pyrite, haüyne (sodalite), diopside, wollastonite, forsterite, calcite, muscovite, humite and other metamorphosed carbonate structures R.D. Rusu, B. Simionescu, A.V. Oancea, M. Geba, L. Stratulat, D. Salajan, L.E. Ursu, M.C. Popescu, M. Dobromir, M.Murariu, C. Cotofana, M. Olaru, Analysis and structural characterization of pigments and materials used in Nicolae Grigorescu heritage paintings, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 168 (2016) 218–229 M. Olaru, B. Simionescu, R.D. Rusu, A.V. Oancea, Examination of pigments and materials used by the Romanian painter Nicolae Grigorescu, Atlas of Science, 2017

4. “Old Lady with Basket” - presents subtle cracks and small abrasions of the paint layer - the varnish is slightly yellowed and matte “The Young Shepherd” - a thin layer of slightly yellowed varnish; a richly ornamented original painting frame “The Return from Fair” - significant cracks, small abrasions of the paint layer, slightly yellowed and matte varnish Analysed points (through optical microscopy and XRF) in the selected NicolaeGrigorescu’s canvases “Old Lady with Basket” - greenish-blue fluorescence of the varnish “The Young Shepherd” - previously cleaned; florescence of an old varnish; white regions and a whitish-yellow bright fluorescence “The Return from Fair” - previously cleaned; yellowing of the varnish layer; white-yellowish bright florescence Infrared (IR) reflectography - the ratio between black and white shades for all paintings; no precursory drawings; no ulterior restorations or interventions UV images IR reflectography images

5. List of identified pigments (by XRF investigations) and their chemical formulas a also confirmed by XPS, b FTIR;, c NIR, and d Raman Representative XRF spectra of the analysed paintings:a. “Old Lady with Basket”, b. “The Shepherd”, c. “The Return from Fair”

6. XPS spectra for C 1s, O 1s, Pb 4f, and S 2p for the prelevated sample taken from “Old Lady with Basket” C1 s spectra – C=C (282.78 eV), C–C/C–H (286.58 eV), C=O (286.11) and O–C=O (288.06 eV) functional groups belonging to linseed oil O 1 s spectra - Ca3(PO4)2 coming from carbon black pigment (530.1 eV), C=O from linseed oil and oxygen atom linked to lead carbonate from hydrocerussite (531.7 eV), O–C=O from the linseed oil; “The Young Shepherd” - O–Si (532.5 eV) from silicates of ochre pigments Si 2p for “The Young Shepherd” – shift of Si–O (101.82 eV, 102.47 eV) as compared to the ones belonging to “The Return from Fair” and “Old Lady with Basket” (102.1 eV), thus pointing out the different nature of the silicate species Pb 4f - Pb from hydrocerussite (138.6 eV), Ca from calcium phosphate (347.6 eV) S 2p3/2 - sulphate SO42− (168.38 eV), sulphite SO32− (166 eV), elemental or native sulphur S0 (164 eV) and polysulphides Sx2− (161.97 eV); the presence of native S0sulphur species points out the existence of natural ultramarine

7. - the only analysed sample evidencing the presence of natural ultramarine was • collected from “The Return from Fair” • - haüyne - absorption bands at 1167 cm−1 (ν3 antisymmetric SO42- ), 665, 693 cm−1 (ν4 antisymmetric SO42 −), 1028, 984 cm−1 (Si–O–Si antisymmetric stretching) • 1007, 665 and 693 cm−1 (Si–O–Al antisymmetric stretching) • Kaolinite - absorption bands located at 3699, 3669, 3657 cm−1 (outer hydroxyl ions), 3620 cm−1 (inner hydroxyl ions), 1028, 1007 cm−1 (Si–O–Si and Si–O–Al, overlapping with the ones from lazurite and haüyne), 938, 909 cm−1 (OH deformation, linked to 2Al3−) Calcite – absorbtion bands from 1401 cm−1 (ν3 antisymmetric CO32– stretching, verlapping with the one from hydrocerussite), 1082 cm−1 (C–O stretching), 874 cm−1 (ν2 out-of-plane bending of CO32–) kaolinite and/or quartz sand – absorption bands from 797 and 779 cm−1 (Si–O–Si inter tetrahedral bonds) Kaolinite - impurity in natural ultramarine, white lead, hematite or green earth; calcite - impurity of lapis lazuli, cinnabar, red ochre or component of the grounds used for the application of oil paints FTIR spectra of the samples collected from the analysed paintings: - The Return from Fair; -The Sheppard; -Old Lady withy Basket.

8. - broad Raman bands between 1320–1340 and1600–1612 cm−1 - presence of amorphous carbon, i.e., carbon black as black pigment - Raman bands from 254, 285 and 342 cm−1 - mercury sulphide (HgS) - hydrocerussite - 1040–1057 cm−1 (ν1 CO32– symmetric stretching vibrations) and 1362–1380 cm−1 (ν3 CO32– antisymmetric stretching vibrations) 245–253 cm−1 peak - main lepidocrocite (γ–FeOOH) Raman band, a component of some natural types of yellow ochres - 835 cm−1 - ν1 stretching vibration of CrO42 − from chrome yellow

9. Near-infrared (NIR) reflectance spectra – presence of linseed oil, proteinaceous materials, as well as some pigments linseed oil, proteinaceous binding: 5687–5717, 5804–5831 cm−1 (1st overtone of symmetric and antisymmetric stretching vibrations of CH2 groups), 4246–4259 cm−1, 4319–4336 cm−1 (symmetric and antisymmetric stretching and bending vibrations of methylenic CH, overlapping with the methylenic CH recombination bands, i.e., stretchings and bendings from lipids constituents of the binder) NIR spectra of “The Young Shepherd” (a) “Old Lady with Basket”, (b) and “The Return from Fair” (c) - shellac - 4246–4259, 4319–4336 cm−1 (stretching and bending vibrations of methylenic CH groups), 5536–5559, 4632–4683 cm−1 (stretching vibrations of OH and CH groups, as well as stretching vibration of carbonyl and methylenic groups) - lead white - 4246–4253 cm−1 (2nd overtone of CO32- groups and stretching and bending vibration of OH groups), 4319–4325 cm−1 (stretching vibration of OH groups and deformation vibrations of Pb–OH groups) - lapis lazuli - 5191–5237 cm−1 (water combination band), and 4532–4559 cm−1 (1st overtone of deformation vibration of SH groups), 4319–4336 cm−1 and 4244–4259 cm−1 (deformation vibration of O–H and Si–O groups) - Kaolinite - 4628–4685, 4525–4567 cm−1 - stretching and bending vibration of coupled OH groups - Burnt amber - 5181–5247 cm−1 (combination of stretching and bending vibrations of OH groups, 4526–4567 cm−1 (stretching vibrations of OH and Si-O groups)

10. - lapis lazuli – presence of blue cubic crystals EDX investigation - compositional information regarding the alumino-silicate nature of the blue pigment, i.e., ultramarine, as well as the presence of Fe and Ca impurities that could arise from red ochres and calcite SEM-EDX microscopies on a sample taken from under the frame of “The Return from Fair” - presence of Fe and Ca in several other areas of the sample that do not contain ultramarine - occurrence of one or more of the other identified pigments containing Ca and Fe-based impurities, i.e., vermillion, red ochre (calcite), white lead (gypsum), as well as red or yellow ochres (Fe)

11. Conclusions - the painter's predilection for a limited group and variety of pigments, common to impressionist painters - the combination of several pigments in each analysed microscopic fragment evidenced that each hue is the result of a mixing process of different proportions of several, diverse pigments - the presence of both carboxylic acids and lead carboxylates evidenced the occurrence of a degradation process in the analyzed paintings - first article to discover and prove the use of natural ultramarine by a painter belonging to the impressionist school - discrepancies between the obtained results, i.e., identification of natural ultramarine in one (by FTIR), two (by XPS) or in all three analyzed heritage canvases (by NIR) can be assumed on the basis of the author's technique and on the specifications of each investigation method - XPS spectroscopy proved to be a valuable tool in identifying the nature of ultramarine (when it was possible to prelevate samples from under the picture frames)