Leonardo and His Cirlce: Painting Technique in the Light of Restorations and Scientific Studies, 2023
Observations on Leonardo's materials and painting technique discussed with reference to his notes... more Observations on Leonardo's materials and painting technique discussed with reference to his notes for a treatise on painting.
Berrie, Barbara H., John K. Delaney, Kathryn A. Dooley, and Lisha D. Glinsman. "Leonardo Da Vinci’s Ginevra De’ Benci: Technical Findings in Light of the Artist’s Notes on Painting." Leonardo and His Circle: Painting Technique in the Light of Restorations and Scientific Studies, Accademia Nazionale dei Lincei, Rome, Bardi Edizioni, Rome, 2023.
I n 1776 marie-daniel bourrée, chevalier de Corberon, secretary to the French minister at St Pete... more I n 1776 marie-daniel bourrée, chevalier de Corberon, secretary to the French minister at St Petersburg, wrote regarding a painting that he had studied in the Russian imperial collection: 'I saw, with sorrow, the Paralytique [Filial piety] by Greuze. It has lost its colour and its effect; it is now a small thing'. 1 Painted some thirteen years earlier by Jean-Baptiste Greuze (1725-1805), this depiction of an elderly patriarch on his sickbed surrounded by his loving family was one of the most celebrated paintings of its time (Fig.2). The rapturous response it elicited at the Salon of 1763 carried as far as the halls of Versailles and in 1765 it was brought to the Court for an official viewing. 2 Its subsequent purchase by Catherine II of Russia made it one of France's most famous artistic Greuze's greens: ephemeral colours, classical ambitions Jean-Baptiste Greuze was criticised in his lifetime for the unduly muted palette of some of his paintings. New technical analysis, combined with the recent discovery of a list in his handwriting of pigments he used, has revealed that his greens have faded because they incorporate fugitive yellow lakes, a practice Greuze continued even after its disadvantages were obvious. by yuriko jackall, barbara h. berrie, john k. delaney and michael swicklik
The use of microspectrophotometry to characterize cochineal in dyed wool is described. The effect... more The use of microspectrophotometry to characterize cochineal in dyed wool is described. The effect of mordants and adjuvants on the absorbance and emission spectra was measured. Chromium, copper, and iron mordants and bases cause a red shift in absorbance spectra while tin and aluminum mordants and acids cause a blue shift. Cochineal mor-danted with tin and aluminum fluoresces while chromium, copper, and iron mordants quench fluorescence. There is a great deal of overlap in the absorbance and emission spectra of the different formulations. A plot of all three emission peak maxima discriminates among substantive, mordanted, and acid-treated unmordanted cochineal. 1 Introduction Many natural organic red colorants have been used as dyes and pigments. Their chemical composition falls into several classes including xanthanes (e.g., rhubarb), flavonoids (e.g., weld), and quinones. Of the quinones, a subset of anthraquinone pigments and dyes can be prepared from either plant or animal sourc...
Formation and aggregation of metal carboxylates (metal soaps) can degrade the appearance and inte... more Formation and aggregation of metal carboxylates (metal soaps) can degrade the appearance and integrity of oil paints, challenging efforts to conserve painted works of art. Endeavors to understand the root cause of metal soap formation have been hampered by the limited spatial resolution of Fourier transform infrared microscopy (μ-FTIR). We overcome this limitation using optical photothermal infrared spectroscopy (O-PTIR) and photothermal-induced resonance (PTIR), two novel methods that provide IR spectra with ≈500 and ≈10 nm spatial resolutions, respectively. The distribution of chemical phases in thin sections from the top layer of a 19th-century painting is investigated at multiple scales (μ-FTIR ≈ 102 μm3, O-PTIR ≈ 10-1 μm3, PTIR ≈ 10-5 μm3). The paint samples analyzed here are found to be mixtures of pigments (cobalt green, lead white), cured oil, and a rich array of intermixed, small (often ≪ 0.1 μm3) zinc soap domains. We identify Zn stearate and Zn oleate crystalline soaps with characteristic narrow IR peaks (≈1530-1558 cm-1) and a heterogeneous, disordered, water-permeable, tetrahedral zinc soap phase, with a characteristic broad peak centered at ≈1596 cm-1. We show that the high signal-to-noise ratio and spatial resolution afforded by O-PTIR are ideal for identifying phase-separated (or locally concentrated) species with low average concentration, while PTIR provides an unprecedented nanoscale view of distributions and associations of species in paint. This newly accessible nanocompositional information will advance our knowledge of chemical processes in oil paint and will stimulate new art conservation practices.
Facture: Conservation Science Art History Volume 3: Degas, 2017
Degas's 'wax' sculptures had been analyzed and found to made from colored... more Degas's 'wax' sculptures had been analyzed and found to made from colored beeswax or a sulfur-based modeling clay, plastilina. This article explores further his use of these materials and compares their formulations to commercially available and artist-prepared modeling materials used by nineteenth-century artists.
Facture: Conservation Science Art History Volume 1: Renaissance Masterworks, 2013
ABSTRACT Giorgio Vasari (1511-1574), architect, painter, and connoiseur, assembled a remarkable c... more ABSTRACT Giorgio Vasari (1511-1574), architect, painter, and connoiseur, assembled a remarkable collection of drawings, referred to as the Libro de' Disegni. A rare and important example is in the collections of the National Gallery of Art, Washington, DC. It is a large, double-sided, richly embellished sheet with drawn frames for nine drawings attributed to the Italian masters Botticelli, Filippino Lippi, and a rare painted work on paper attributed to Rafaellino del Garbo (NGA accession 1991.190.1). This investigation reveals how Vasari constructed the sheet, addresses how it may have been bound, and offers a brief description of the materials used for creating the page and the ten works the comprise the page. Non-sampling methods used for the study include infrared imaging, x-ray fluorescence spectroscopy and optical microscopy.
Materials in the paint layers of an early sixteenth-century painted and glazed terracotta sculptu... more Materials in the paint layers of an early sixteenth-century painted and glazed terracotta sculpture by Giovanni della Robbia, Pietà were identified. The presence of the rare lead chloride salts, cotunnite (PbCl2) and challacolloite (KPb2Cl5), were confirmed using Raman spectroscopy and electron back scatter diffraction. Well-formed habit of large crystals of challacolloite indicates slow growth from solution. The stability and potential pathways for the in-situ formation of lead chloride compounds are discussed. The presence of lead chloride phases in the Pietà indicates conditions of high chloride ion concentrations (i.e., activities) and/or low pH led to the alteration of the pigment lead white (hydrocerussite, 2PbCO3·Pb(OH)2). This work highlights the role of ion transport in alteration of artists' materials and emphasizes the importance of considering the role of treatments and envi-ronmental factors in changes in materials, and reinforces our awareness of the on-going chemistry occurring in works of art.
Background: Color change in artworks has been commented on for centuries. Fading of watercolor pi... more Background: Color change in artworks has been commented on for centuries. Fading of watercolor pigments is a notable alteration. Pigments based on carminic acid are among those particularly prone to color loss, but the mechanism and factors are not well understood. Results: We painted out three pigments prepared from the aqueous extract of carminic acid (CA) from Dactylopius coccus: the uncomplexed, and aluminium-and tin-complexed lakes. These were applied in a 2% gum Arabic solution to papers that were acidic, neutral or alkaline pH and exposed to accelerated light aging in a weatherometer. The comparative rate of fading was dependent on the complexation and on the pH of the substrate. On alkaline paper, the Al complex was least light stable, on neutral paper the three colorants responded similarly, and on acidic paper the tin complex was the least light stable. This is discussed in light of the published information on reactions and mechanism of color loss of CA.
Single-sided NMR and gas chromatography were used in tandem to investigate the physical and chemi... more Single-sided NMR and gas chromatography were used in tandem to investigate the physical and chemical differences between traditional linseed oil paint and water-mixable oil paint. Water-mixable oil paints contain an emulsifier that confers water miscibility, but it may also affect the curing process and the intermolecular network formed in a cured paint film. Comparisons of paint samples of different compositions and ages show that the emulsifier changes both the chemical and physical properties of the paint films, though at different curing times and to different extents depending on the paint formulation. This research highlights the utility of NMR relaxometry in cultural heritage analysis, and suggests further study into the effects of agents affecting the curing process and reactions within a paint film.
To investigate soap formation in drying oils in historic paints, the reaction between metal aceta... more To investigate soap formation in drying oils in historic paints, the reaction between metal acetates (K + , Zn 2+ , Pb 2+) and ethyl linoleate (EL) was studied using optical microscopy, X-ray powder diffraction, and electron microscopy. Pb(II) and Zn(II) react rapidly with EL to form highly structured, spherulitic, luminescent crystallites that aggregate. Evidence from Fourier transform infrared (FTIR) and scanning electron microscopy/energy dispersive X-ray analysis and high-resolution synchrotron powder X-ray diffraction indicates that these are organic−inorganic hybrid complexes or coordination polymers. FTIR absorbance peaks at ca. 1540 cm −1 for Pb(II) and ca. 1580 cm −1 for Zn(II) are consistent with the formation of carboxylate complexes. The complexes formed offer insight into the degradation processes observed in oil paint films, suggesting that soap formation is rapid when metal ions are solubilized and can occur with unsaturated fatty acids that are present in fresh oils. These complexes may account for the atypical luminescence observed in lead-containing cured oil paint films.
Chemphyschem : a European journal of chemical physics and physical chemistry, Jan 7, 2016
We report the influence of adding five short-chain glycol ethers (SCGEs) on the structure, stabil... more We report the influence of adding five short-chain glycol ethers (SCGEs) on the structure, stability, and viscoelastic properties of aqueous dispersions of partially hydrolyzed poly(vinyl acetate) and borax. The properties of these gel-like materials have been investigated as a function of the structure of the added SCGE both below and above the critical aggregation (or micellar) concentrations using (11) B and (13) C NMR, rheology, and small-angle neutron scattering. The results indicate that the SCGE aggregation behavior is not affected by incorporation into the gel-like network. However, changes in the viscoelasticity and structural properties of the dispersions were detected that can be correlated to the nature of the solvent system. Also, the ability of these materials to clean an unvarnished acrylic paint surface coated with synthetic soil has been evaluated using colorimetery, and the surface of the dispersion after cleaning was visualized with scanning electron microscopy.
Background: The important trecento Florentine artist Giotto (c. 1266-1337) is renowned for his na... more Background: The important trecento Florentine artist Giotto (c. 1266-1337) is renowned for his naturalistic and realistic works in tempera and fresco. His innovative paintng style involved painting expressive, emotive faces and use of pictorial devices for depicting space. This report focuses on the analysis of the materials and methods used in a panel in the collection of the National Gallery of Art, Madonna and Child (1310/1315). Results: Giotto used inky washes under thin layers of egg tempera paint. Yellow iron earth and lead tin yellow are present in the paint used to depict the lining of the Virgin's mantle. SEM-EDX of one of the yellow pigments confirmed it is lead tin yellow type II, PbSn 1-x Si x O 3. The ratio of colorant to the glassy phase indicates this material was produced for use as a pigment rather than as a glass. Ultramarine was not used in this painting, azurite is the blue pigment. The azurite used here does not contain elemental impurities, however malachite and the rare green-blue mineral mixite, BiCu 6 (OH) 6 (AsO 4) 3 (H 2 O) 3 , are found in the blue paint.
In the sixteenth century, the Erzgebirge mountains were mined for mineral ores of cobalt and anti... more In the sixteenth century, the Erzgebirge mountains were mined for mineral ores of cobalt and antimony that were used to make the blue pigment smalt, a potash glass, and yellow pigments based on lead-antimony oxides, respectively. By the beginning of the seventeenth century, these pigments had found a permanent place on the easel painter’s palette, smalt used in place of ultramarine and the antimonial compounds enlivening the yellows of the spectrum. Mining efforts also located sources for naphtha, and improvements in distillation would have allowed it (and other solvents) to be fractioned and purified for use as a solvent and diluent for oil paint. The mention of naphtha in treatises and color-sellers’ inventories attests to its use in color making. Thinning paint allowed artists to use glazes of paint to lively, luminous, coloristic effect and made blending easier. These three discoveries contributed to the saturated colors characteristic of seventeenth-century painting and offered...
Venice was renowned as a centre for the production of corrosive substances, including lead white.... more Venice was renowned as a centre for the production of corrosive substances, including lead white. Documentary evidence illustrate the large extent of production and exportation of these substances. Sixteenth- and seventeenth-century commentators provide anecdotal evidence for the superior quality of Venetian lead white. Analysis of the pigment in cross-sections provides evidence for at least two grades of lead white and careful and extensive processing of the product.
Leonardo and His Cirlce: Painting Technique in the Light of Restorations and Scientific Studies, 2023
Observations on Leonardo's materials and painting technique discussed with reference to his notes... more Observations on Leonardo's materials and painting technique discussed with reference to his notes for a treatise on painting.
Berrie, Barbara H., John K. Delaney, Kathryn A. Dooley, and Lisha D. Glinsman. "Leonardo Da Vinci’s Ginevra De’ Benci: Technical Findings in Light of the Artist’s Notes on Painting." Leonardo and His Circle: Painting Technique in the Light of Restorations and Scientific Studies, Accademia Nazionale dei Lincei, Rome, Bardi Edizioni, Rome, 2023.
I n 1776 marie-daniel bourrée, chevalier de Corberon, secretary to the French minister at St Pete... more I n 1776 marie-daniel bourrée, chevalier de Corberon, secretary to the French minister at St Petersburg, wrote regarding a painting that he had studied in the Russian imperial collection: 'I saw, with sorrow, the Paralytique [Filial piety] by Greuze. It has lost its colour and its effect; it is now a small thing'. 1 Painted some thirteen years earlier by Jean-Baptiste Greuze (1725-1805), this depiction of an elderly patriarch on his sickbed surrounded by his loving family was one of the most celebrated paintings of its time (Fig.2). The rapturous response it elicited at the Salon of 1763 carried as far as the halls of Versailles and in 1765 it was brought to the Court for an official viewing. 2 Its subsequent purchase by Catherine II of Russia made it one of France's most famous artistic Greuze's greens: ephemeral colours, classical ambitions Jean-Baptiste Greuze was criticised in his lifetime for the unduly muted palette of some of his paintings. New technical analysis, combined with the recent discovery of a list in his handwriting of pigments he used, has revealed that his greens have faded because they incorporate fugitive yellow lakes, a practice Greuze continued even after its disadvantages were obvious. by yuriko jackall, barbara h. berrie, john k. delaney and michael swicklik
The use of microspectrophotometry to characterize cochineal in dyed wool is described. The effect... more The use of microspectrophotometry to characterize cochineal in dyed wool is described. The effect of mordants and adjuvants on the absorbance and emission spectra was measured. Chromium, copper, and iron mordants and bases cause a red shift in absorbance spectra while tin and aluminum mordants and acids cause a blue shift. Cochineal mor-danted with tin and aluminum fluoresces while chromium, copper, and iron mordants quench fluorescence. There is a great deal of overlap in the absorbance and emission spectra of the different formulations. A plot of all three emission peak maxima discriminates among substantive, mordanted, and acid-treated unmordanted cochineal. 1 Introduction Many natural organic red colorants have been used as dyes and pigments. Their chemical composition falls into several classes including xanthanes (e.g., rhubarb), flavonoids (e.g., weld), and quinones. Of the quinones, a subset of anthraquinone pigments and dyes can be prepared from either plant or animal sourc...
Formation and aggregation of metal carboxylates (metal soaps) can degrade the appearance and inte... more Formation and aggregation of metal carboxylates (metal soaps) can degrade the appearance and integrity of oil paints, challenging efforts to conserve painted works of art. Endeavors to understand the root cause of metal soap formation have been hampered by the limited spatial resolution of Fourier transform infrared microscopy (μ-FTIR). We overcome this limitation using optical photothermal infrared spectroscopy (O-PTIR) and photothermal-induced resonance (PTIR), two novel methods that provide IR spectra with ≈500 and ≈10 nm spatial resolutions, respectively. The distribution of chemical phases in thin sections from the top layer of a 19th-century painting is investigated at multiple scales (μ-FTIR ≈ 102 μm3, O-PTIR ≈ 10-1 μm3, PTIR ≈ 10-5 μm3). The paint samples analyzed here are found to be mixtures of pigments (cobalt green, lead white), cured oil, and a rich array of intermixed, small (often ≪ 0.1 μm3) zinc soap domains. We identify Zn stearate and Zn oleate crystalline soaps with characteristic narrow IR peaks (≈1530-1558 cm-1) and a heterogeneous, disordered, water-permeable, tetrahedral zinc soap phase, with a characteristic broad peak centered at ≈1596 cm-1. We show that the high signal-to-noise ratio and spatial resolution afforded by O-PTIR are ideal for identifying phase-separated (or locally concentrated) species with low average concentration, while PTIR provides an unprecedented nanoscale view of distributions and associations of species in paint. This newly accessible nanocompositional information will advance our knowledge of chemical processes in oil paint and will stimulate new art conservation practices.
Facture: Conservation Science Art History Volume 3: Degas, 2017
Degas's 'wax' sculptures had been analyzed and found to made from colored... more Degas's 'wax' sculptures had been analyzed and found to made from colored beeswax or a sulfur-based modeling clay, plastilina. This article explores further his use of these materials and compares their formulations to commercially available and artist-prepared modeling materials used by nineteenth-century artists.
Facture: Conservation Science Art History Volume 1: Renaissance Masterworks, 2013
ABSTRACT Giorgio Vasari (1511-1574), architect, painter, and connoiseur, assembled a remarkable c... more ABSTRACT Giorgio Vasari (1511-1574), architect, painter, and connoiseur, assembled a remarkable collection of drawings, referred to as the Libro de' Disegni. A rare and important example is in the collections of the National Gallery of Art, Washington, DC. It is a large, double-sided, richly embellished sheet with drawn frames for nine drawings attributed to the Italian masters Botticelli, Filippino Lippi, and a rare painted work on paper attributed to Rafaellino del Garbo (NGA accession 1991.190.1). This investigation reveals how Vasari constructed the sheet, addresses how it may have been bound, and offers a brief description of the materials used for creating the page and the ten works the comprise the page. Non-sampling methods used for the study include infrared imaging, x-ray fluorescence spectroscopy and optical microscopy.
Materials in the paint layers of an early sixteenth-century painted and glazed terracotta sculptu... more Materials in the paint layers of an early sixteenth-century painted and glazed terracotta sculpture by Giovanni della Robbia, Pietà were identified. The presence of the rare lead chloride salts, cotunnite (PbCl2) and challacolloite (KPb2Cl5), were confirmed using Raman spectroscopy and electron back scatter diffraction. Well-formed habit of large crystals of challacolloite indicates slow growth from solution. The stability and potential pathways for the in-situ formation of lead chloride compounds are discussed. The presence of lead chloride phases in the Pietà indicates conditions of high chloride ion concentrations (i.e., activities) and/or low pH led to the alteration of the pigment lead white (hydrocerussite, 2PbCO3·Pb(OH)2). This work highlights the role of ion transport in alteration of artists' materials and emphasizes the importance of considering the role of treatments and envi-ronmental factors in changes in materials, and reinforces our awareness of the on-going chemistry occurring in works of art.
Background: Color change in artworks has been commented on for centuries. Fading of watercolor pi... more Background: Color change in artworks has been commented on for centuries. Fading of watercolor pigments is a notable alteration. Pigments based on carminic acid are among those particularly prone to color loss, but the mechanism and factors are not well understood. Results: We painted out three pigments prepared from the aqueous extract of carminic acid (CA) from Dactylopius coccus: the uncomplexed, and aluminium-and tin-complexed lakes. These were applied in a 2% gum Arabic solution to papers that were acidic, neutral or alkaline pH and exposed to accelerated light aging in a weatherometer. The comparative rate of fading was dependent on the complexation and on the pH of the substrate. On alkaline paper, the Al complex was least light stable, on neutral paper the three colorants responded similarly, and on acidic paper the tin complex was the least light stable. This is discussed in light of the published information on reactions and mechanism of color loss of CA.
Single-sided NMR and gas chromatography were used in tandem to investigate the physical and chemi... more Single-sided NMR and gas chromatography were used in tandem to investigate the physical and chemical differences between traditional linseed oil paint and water-mixable oil paint. Water-mixable oil paints contain an emulsifier that confers water miscibility, but it may also affect the curing process and the intermolecular network formed in a cured paint film. Comparisons of paint samples of different compositions and ages show that the emulsifier changes both the chemical and physical properties of the paint films, though at different curing times and to different extents depending on the paint formulation. This research highlights the utility of NMR relaxometry in cultural heritage analysis, and suggests further study into the effects of agents affecting the curing process and reactions within a paint film.
To investigate soap formation in drying oils in historic paints, the reaction between metal aceta... more To investigate soap formation in drying oils in historic paints, the reaction between metal acetates (K + , Zn 2+ , Pb 2+) and ethyl linoleate (EL) was studied using optical microscopy, X-ray powder diffraction, and electron microscopy. Pb(II) and Zn(II) react rapidly with EL to form highly structured, spherulitic, luminescent crystallites that aggregate. Evidence from Fourier transform infrared (FTIR) and scanning electron microscopy/energy dispersive X-ray analysis and high-resolution synchrotron powder X-ray diffraction indicates that these are organic−inorganic hybrid complexes or coordination polymers. FTIR absorbance peaks at ca. 1540 cm −1 for Pb(II) and ca. 1580 cm −1 for Zn(II) are consistent with the formation of carboxylate complexes. The complexes formed offer insight into the degradation processes observed in oil paint films, suggesting that soap formation is rapid when metal ions are solubilized and can occur with unsaturated fatty acids that are present in fresh oils. These complexes may account for the atypical luminescence observed in lead-containing cured oil paint films.
Chemphyschem : a European journal of chemical physics and physical chemistry, Jan 7, 2016
We report the influence of adding five short-chain glycol ethers (SCGEs) on the structure, stabil... more We report the influence of adding five short-chain glycol ethers (SCGEs) on the structure, stability, and viscoelastic properties of aqueous dispersions of partially hydrolyzed poly(vinyl acetate) and borax. The properties of these gel-like materials have been investigated as a function of the structure of the added SCGE both below and above the critical aggregation (or micellar) concentrations using (11) B and (13) C NMR, rheology, and small-angle neutron scattering. The results indicate that the SCGE aggregation behavior is not affected by incorporation into the gel-like network. However, changes in the viscoelasticity and structural properties of the dispersions were detected that can be correlated to the nature of the solvent system. Also, the ability of these materials to clean an unvarnished acrylic paint surface coated with synthetic soil has been evaluated using colorimetery, and the surface of the dispersion after cleaning was visualized with scanning electron microscopy.
Background: The important trecento Florentine artist Giotto (c. 1266-1337) is renowned for his na... more Background: The important trecento Florentine artist Giotto (c. 1266-1337) is renowned for his naturalistic and realistic works in tempera and fresco. His innovative paintng style involved painting expressive, emotive faces and use of pictorial devices for depicting space. This report focuses on the analysis of the materials and methods used in a panel in the collection of the National Gallery of Art, Madonna and Child (1310/1315). Results: Giotto used inky washes under thin layers of egg tempera paint. Yellow iron earth and lead tin yellow are present in the paint used to depict the lining of the Virgin's mantle. SEM-EDX of one of the yellow pigments confirmed it is lead tin yellow type II, PbSn 1-x Si x O 3. The ratio of colorant to the glassy phase indicates this material was produced for use as a pigment rather than as a glass. Ultramarine was not used in this painting, azurite is the blue pigment. The azurite used here does not contain elemental impurities, however malachite and the rare green-blue mineral mixite, BiCu 6 (OH) 6 (AsO 4) 3 (H 2 O) 3 , are found in the blue paint.
In the sixteenth century, the Erzgebirge mountains were mined for mineral ores of cobalt and anti... more In the sixteenth century, the Erzgebirge mountains were mined for mineral ores of cobalt and antimony that were used to make the blue pigment smalt, a potash glass, and yellow pigments based on lead-antimony oxides, respectively. By the beginning of the seventeenth century, these pigments had found a permanent place on the easel painter’s palette, smalt used in place of ultramarine and the antimonial compounds enlivening the yellows of the spectrum. Mining efforts also located sources for naphtha, and improvements in distillation would have allowed it (and other solvents) to be fractioned and purified for use as a solvent and diluent for oil paint. The mention of naphtha in treatises and color-sellers’ inventories attests to its use in color making. Thinning paint allowed artists to use glazes of paint to lively, luminous, coloristic effect and made blending easier. These three discoveries contributed to the saturated colors characteristic of seventeenth-century painting and offered...
Venice was renowned as a centre for the production of corrosive substances, including lead white.... more Venice was renowned as a centre for the production of corrosive substances, including lead white. Documentary evidence illustrate the large extent of production and exportation of these substances. Sixteenth- and seventeenth-century commentators provide anecdotal evidence for the superior quality of Venetian lead white. Analysis of the pigment in cross-sections provides evidence for at least two grades of lead white and careful and extensive processing of the product.
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Papers by Barbara Berrie
Berrie, Barbara H., John K. Delaney, Kathryn A. Dooley, and Lisha D. Glinsman. "Leonardo Da Vinci’s Ginevra De’ Benci: Technical Findings in Light of the Artist’s Notes on Painting." Leonardo and His Circle: Painting Technique in the Light of Restorations and Scientific Studies, Accademia Nazionale dei Lincei, Rome, Bardi Edizioni, Rome, 2023.
Berrie, Barbara H., John K. Delaney, Kathryn A. Dooley, and Lisha D. Glinsman. "Leonardo Da Vinci’s Ginevra De’ Benci: Technical Findings in Light of the Artist’s Notes on Painting." Leonardo and His Circle: Painting Technique in the Light of Restorations and Scientific Studies, Accademia Nazionale dei Lincei, Rome, Bardi Edizioni, Rome, 2023.