Catherine Higgitt

• Doctor of Philosophy
• National Gallery, London

High-quality element distribution maps enable precise analysis of the material composition and condition of Old Master paintings. These maps are typically produced from data acquired through Macro X-ray fluorescence (MA-XRF) scanning, a non-invasive technique that collects spectral information. However, MA-XRF is often limited by a trade-off betwee...

The anniversary in 2019 of Leonardo’s death prompted a new investigation of the Virgin of the Rocks now in the National Gallery in London. This built on a substantial foundation of earlier research, one past milestone being the discovery through infrared reflectography of an underdrawing for a completely different composition, showing a Virgin high...

During the conservation of easel paintings, black draperies or dark backgrounds often prove problematic to treat and understand in terms of condition. Despite most black pigments in Old Master paintings not intrinsically containing high atomic number elements, the investigation of black paints is one of the National Gallery's major uses and most he...

Macro X-ray Fluorescence (MA-XRF) scanning is increasingly widely used by researchers in heritage science to analyse easel paintings as one of a suite of non-invasive imaging techniques. The task of processing the resulting MA-XRF datacube generated in order to produce individual chemical element maps is called MA-XRF deconvolution. While there are...

This is our poster presented at ICASSP 2023 - 2023 IEEE International Conference on Acoustics, Speech and Signal Processing, for our paper titled 'Super-Resolution for Macro X-Ray Fluorescence Data Collected from Old Master Paintings'.

X-radiography (X-ray imaging) is a widely used imaging technique in art investigation. It can provide information about the condition of a painting as well as insights into an artist’s techniques and working methods, often revealing hidden information invisible to the naked eye. X-radiograpy of double-sided paintings results in a mixed X-ray image...

Macro X-ray fluorescence (MA-XRF) scanning is commonly used to non-invasively analyse Old Master paintings by mapping the distribution of the chemical elements present in the artworks. The visual quality of the element distribution maps is very important for characterising the materials and understanding the execution and condition of the painting....

Macro X-ray Fluorescence (MA-XRF) scanning is increasingly widely used by researchers in heritage science to analyse easel paintings as one of a suite of non-invasive imaging techniques. The task of processing the resulting MA-XRF datacube generated in order to produce individual chemical element maps is called MA-XRF deconvolution. While there are...

In recent decades, cultural heritage research – and in particular art investigation – has been undergoing a digital revolution. This is due both to improvements in the digitization and the acquisition of artefact's images generated using traditional 2D imaging methods as well as the growing adoption of a range of more recently introduced spectrosco...

Undertaking the conservation of artworks informed by the results of molecular analyses has gained growing importance over the last decades, and today it can take advantage of state-of-the-art analytical techniques, such as mass spectrometry-based proteomics. Protein-based binders are among the most common organic materials used in artworks, having...

X-ray fluorescence (XRF) spectroscopy is an analytical technique used to identify chemical elements that has found widespread use in the cultural heritage sector to characterise artists' materials including the pigments in paintings. It generates a spectrum with characteristic emission lines relating to the elements present, which is interpreted by...

In this paper, we focus on X-ray images (X-radiographs) of paintings with concealed sub-surface designs ( e.g. , deriving from reuse of the painting support or revision of a composition by the artist), which therefore include contributions from both the surface painting and the concealed features. In particular, we propose a self-supervised deep l...

Macro X-ray fluorescence (MA-XRF) scanning is commonly used to non-invasively analyse Old Master paintings by mapping the distribution of the chemical elements present in the artworks. The visual quality of the element distribution maps is very important for characterising the materials and understanding the execution and condition of the painting....

In this paper, we focus on X-ray images of paintings with concealed sub-surface designs (e.g., deriving from reuse of the painting support or revision of a composition by the artist), which include contributions from both the surface painting and the concealed features. In particular, we propose a self-supervised deep learning-based image separatio...

X-ray images are widely used in the study of paintings. When a painting has hidden sub-surface features (e.g., reuse of the canvas or revision of a composition by the artist), the resulting X-ray images can be hard to interpret as they include contributions from both the surface painting and the hidden design. In this paper we propose a self-superv...

This supplementary material includes the results produced by our proposed method with the MA-XRF dataset collected on another easel painting (Diana and Callisto created by Titian). In this dataset, the chemical elements that are difficult to be separated are iron (Fe) and cobalt (Co). With the results, we demonstrate that our proposed method is abl...

Macro X-ray Fluorescence (MA-XRF) scanning is an increasingly widely used technique for analytical imaging of paintings and other artworks. The datasets acquired must be processed to produce maps showing the distribution of the chemical elements that are present in the painting. Existing approaches require varying degrees of expert user interventio...

The fugitive nature of the colorants obtained from sappanwood (Caesalpinia sappan L.) or the South American species commonly known as ‘brazilwoods’ (including other Caesalpinia species and Paubrasilia echinata (Lam.)) makes the identification of brazilwood dyes and pigments in historic artefacts analytically challenging. This difficulty has been so...

X-radiography (X-ray imaging) is a widely used imaging technique in art investigation. It can provide information about the condition of a painting as well as insights into an artist's techniques and working methods, often revealing hidden information invisible to the naked eye. In this paper, we deal with the problem of separating mixed X-ray imag...

Macro X-Ray Fluorescence (XRF) scanning is an increasingly widely used imaging technique for the non-invasive detection and mapping of chemical elements in Old Master paintings. Existing approaches for XRF signal analysis require varying degrees of expert user input. They are mainly based on peak fitting at fixed energies associated with each eleme...

Vibration generated by use of masonry equipment can be a threat to wall paintings. Its assessment, mitigation and control is of critical importance to risk management and the safeguarding of works of art, particularly those which are immovable. The planned programme of window restoration in the Royal Gallery, Palace of Westminster, started in 2016,...

X-ray images of polyptych wings, or other artworks painted on both sides of their support, contain in one image content from both paintings, making them difficult for experts to “read.” To improve the utility of these x-ray images in studying these artworks, it is desirable to separate the content into two images, each pertaining to only one side....

Vincent van Gogh's Sunflowers are seen by many as icons of Western European art. Two of these masterpieces - the first version painted in August 1888 (The National Gallery, London) and the painting made after it in January 1889 (Van Gogh Museum, Amsterdam) - have been the subject of a detailed comparison by an interdisciplinary team of experts. The...

NOTE: this book can not be shared via Researchgate (also not via private mail) it is for sale via the DOI given above. Vincent van Gogh's Sunflowers are seen by many as icons of Western European art. Two of these masterpieces — the first version painted in August 1888 (The National Gallery, London) and the painting made after it in January 1889 (Va...

During the conservation treatment of Memling’s Christ with Singing and Music-making Angels, three panel paintings that are among the most monumental works in early Netherlandish art, the conservators came across insoluble surface layers containing calcium oxalates. A very thin and irregular layer of this type, hardly visible to the naked eye, was s...

Like many museums and galleries following a prolonged period of austerity, the National Gallery has increased its public, private and corporate activities on an unprecedented scale and embarked on an extensive building programme to develop the site and its heritage-listed building. Together with an expanding loans and exhibitions programme, institu...

Small workbaskets containing assemblages of tools and materials used in textile production are fairly common in later pre- Hispanic funerary contexts in Andean coastal regions. Many of these baskets that are now preserved in museum collections were collected in the late nineteenth and early twentieth century. Although most lack firm provenance and...

On 4 June 2014 the famous early Chinese painting, Admonitions of the Instructress to the Court Ladies (Nüshi zhen tu女史箴圖: British Museum OA 1903,0408.0,1), was redisplayed at the British Museum in a new purpose-built case. This marked the end of a five year period of investigation, consultation, conservation and rehousing of the handscroll, which h...

Textiles with exceptionally well-preserved colours were found associated with a naturally-mummified body from the medieval period (AD 600-1500) found in the Fourth Cataract region of the Nile in Sudan. The body and its wrappings are rare survivals, preserved due to their burial in consistently dry conditions. The textiles were investigated as part...

A collection of 1980s Mexican rubberised cotton garments was investigated in order to assess conservation treatment options, to improve their long term storage conditions and to investigate the origin of the strong odour associated with the garments. Chemical and mechanical deterioration of the rubber was confirmed by Fourier transform infrared (FT...

This paper describes the development of a novel non-invasive sampling and analysis method that can be used to assess the presence of volatile pesticides on objects held in heritage collections. Vapour phase sampling was conducted using sampling tubes loaded with Tenax-TA™ and trapped analytes were determined using thermal desorption-gas chromatogra...

The root of the madder plant (Rubia spp.) has been used for textile dyeing and pigment making for millennia and madder-derived dyes and pigments were widely used in antiquity. Pigments made from madder have been found on objects in the British Museum, particularly those from Greek, Roman, Parthian and Egyptian contexts, and the analyses of a number...

Since being recognised as a potential emissive source, plastics in heritage collections are being investigated to understand the chemical compounds they release and how they might affect the stability of other heritage objects. There is a requirement for non-invasive methods of analyses to identify unknown plastics and the emitted volatiles they ge...

A fifteenth-century decorative parade shield (1863,0501.1) held at the British Museum is a finely crafted, three-dimensional object thought to be of Burgundian origin. Little was known about its painting technique, construction, and function before the study presented in this paper. Concerns over the object's stability and specific mounting needs f...

In 2010 a group of 20 decorative ivory and bone plaques from the late first-century ad Kushan citysite at Begram, Afghanistan arrived on deposit at the British Museum (BM). The plaques had only recently been rediscovered after being looted from the National Museum of Afghanistan (NMA) in Kabul during the height of the Afghan civil war (1992–1994),...

The British Museum houses a significant collection of organic material from prehistoric Swiss lake dwellings (c.4000 to 500 bc) excavated in the late nineteenth century. The waterlogged, anaerobic, alkaline burial environment provided conditions suitable for the preservation of a range of organic materials including many textiles. The textiles, whi...

Iron gall inks are of extraordinary historical significance considering their widespread use for over a millennium. Due to their corrosiveness, which is a consequence of their acidity and content of transition metals, iron gall inks accelerate the degradation of the writing or drawing support, which in this study is rag paper. Characterisation of a...

The unique nature and typically small size of samples, the effects of time and past treatment and the diverse range of potential biological sources make identification of the natural organic colorant source for dyes and pigments in cultural heritage contexts highly challenging. Selection of the most appropriate extraction method to solubilise the c...

An Ethiopian mural painting on a cotton support, The Crucifixion of Christ (Af1893,1112.1), was donated to the British Museum in 1893. The preparations for its exhibition brought together a multidisciplinary team of British museum professionals and community advisors from both the UK and Ethiopia to research, analyse and conserve the painting, whic...

Naples yellow-containing oil paints aged under natural and artificial conditions were investigated as model systems to evaluate the potential of secondary ion mass spectrometry (SIMS) when used in combination with other mass spectrometric and spectroscopic analytical methods. Although the advantage of SIMS is the simultaneous detection of organic a...

The aging of natural triterpenoid resins used as varnishes on paintings is still insufficiently understood. Although progress has been made, questions concerning the aging pathways in light vs. darkness, or the correlation of oxidation with yellowing, remain open. The influence of aging conditions, primarily the amount of light, but also resin comp...

Using pyrolysis-gas chromatography/mass spectrometry and Fourier transform infrared spectroscopy, the authors show that amber was imported into Late Bronze Age Syria and used for making the prestige artefacts found in a Royal tomb of c. 1340 BC. The objects included beads and a unique vessel in the form of a lion, likely fashioned in Syria from raw...

An unusual green pigment was found on a seventeenth-century kuan cai (Coromandel) lacquer screen at the Victoria and Albert Museum, London. The particles are perfectly spherical and translucent, with the appearance of green fish roe. Analysis revealed that the pigment is a copper resinate, produced by reacting a copper salt with a resin, probably o...

Cochineal and, later, madder were the most important natural dyes used for red lake pigments in the eighteenth and nineteenth centuries. However, as a result of developments in the technology of the dyestuffs and in the processes involved in pigment making, eighteenth- and nineteenth-century lakes show important differences to those made from the s...

Vasari listed Giannicola di Paolo (active 1499; died 1544) as one of Perugino's discepoli, that is, someone trained in his workshop. The technical examination of the National Gallery's Annunciation (NG 1104) of around 1500 attributed to Giannicola is presented, and the insight the study gives into the operation of Perugino's workshop is discussed....

The substrate of a traditional red lake pigment, usually assumed to be a form of hydrated alumina, is as important a constituent as the dyestuff, influencing its colour, transparency, working properties and permanence. Analysis of both inorganic and organic constituents was carried out on lake pigments made in the laboratory following historical re...

The results of examination of paintings in the National Gallery in which the blue cobalt glass pigment smalt has degraded are presented. The appearance on the paint surface is described; the smalt does not only lose its colour but also causes yellowing of the oil so that the paint appears brownish-yellow or greenish grey. Other paint defects are di...

This article represents a major survey of new results of paint medium analyses for a range of Italian paintings of the fifteenth and sixteenth centuries in the National Gallery collection using, principally, FTIR spectrometry and gas-chromatography linked to mass-spectrometry. The results are divided between Florentine, Sienese, Umbrian, North Ital...

The tiny white inclusions that appear in the surface of old-master oil paintings are discussed. These inclusions consist of lead soaps which are formed by the reaction of metal-based pigments with the oil used to make paints. They indicate that the paintings are undergoing serious deterioration process, different from the usual changes that occur w...

Lead(II) carboxylate soaps of two fatty acids, palmitic (C15H31COOH) and stearic acids (C17H35COOH), and a dicarboxylic acid, azelaic acid (HOOCC7H14COOH), have been synthesised and characterised by FTIR spectroscopy. These acids are all encountered in aged traditional oil paint, the azelaic acid resulting from the oxidative degradation of unsatura...

Translucent white lumps or inclusions in red lead and lead-tin yellow type I paint layers are discussed in detail. These lumps are described as varying in size. Most often visible under the microscope and sometimes to the naked eye, the inclusions impart a gritty texture to paint films. Inclusions are found to be ubiquitous in European oil painting...

UV irradiation of [(η5-C5Me5)Re(CO)2N2] in neat 1,4-C6H4F2 generates a mixture of the C–H activation product trans-[(η5-C5Me5)Re(CO)2(2,5-C6H3F2)H] 1a and the η2-arene complex [(η5-C5Me5)Re(CO)2(2,3-η2-1,4-C6H4F2)] 2a, identified on the basis of their IR and NMR spectra. Reaction of the mixture with CHBr3 allowed the isolation of trans-[(η5-C5Me5)R...

Reaction of [Ni(COD)2] with PEt3 and octafluoronaphthalene yielded the complex [Ni(η2-1,2-C10F8)(PEt3)2] 1, which was converted thermally into the C–F activation product trans-[NiF(2-C10F7)(PEt3)2] 2. The crystal structure of 1 shows asymmetric η2 coordination with significant distortions of the naphthalene unit compared to the “ free” ligand; DFT...

Complexes of naphthalene and phenanthrene with rhodium( 5 -cyclopentadienyl)(trimethylphosphine) have been studied by quantitative two-dimensional nuclear Overhauser (NOESY) and exchange spectroscopy (EXSY). Naphthalene coordinates in the 2 -1,2-mode as ( 5 -C5H5)Rh(PMe3)( 2 -C10H8). At 260 K, NOESY peaks establish that the solution conformer has t...

Complexes of naphthalene and phenanthrene with rhodium( 5-cyclopentadienyl)(tri- methylphosphine) have been studied by quantitative two-dimensional nuclear Overhauser (NOESY) and exchange spectroscopy (EXSY). Naphthalene coordinates in the 2-1,2-mode as ( 5-C5H5)Rh(PMe3)( 2-C10H8). At 260 K, NOESY peaks establish that the solution conformer has the...

UV Irradiation of [Re(η5-C5R5)(CO)3] (R = Me or H) in the presence of C6F5H or 1,2,4,5-C6F4H2 effected intramolecular C–H activation, generating the hydrido complexes trans-[Re(η5-C5R5)(CO)2(Ar)FH] [(Ar)F = C6F5 or 2,3,5,6-C6F4H] as the principal photochemical products. The identities of the hydrido complexes were confirmed by independent thermal s...

Bis(η6-benzene)chromium reacts with hexafluorobenzene to yield a red charge-transfer complex [Cr(η6-C6H6)2•C6F6] which contains stacks of alternating donor and acceptor molecules with close inter- and intrastack contacts; in addition to the charge-transfer complex, formation of [Cr(η6-C6H6)2]+ is demonstrated by EPR and IR spectroscopy.

The unsaturated PCP-type complexes Rh(L){2,6-(CH2PtBu2)2C6H3}X (L = Et, nPr; X = Cl, I) complexes convert upon heating to the corresponding Rh(III)−hydride complexes Rh(H){2,6-(CH2PtBu2)2C6H3}X (X = Cl, I) and ethylene or propylene, products indicative of a β-H elimination process. The iPr analogue is observed upon reaction of Rh(η1-N2){2,6-(CH2PtB...

The UV irradiation of [Re(η5-C5Me5)(CO)3] in the presence of C6F6 effected intermolecular C–F and intramolecular C–H activation generating [Re(η6-C5Me4CH2)(CO)2(C6F5)] 1a in two isomeric forms. In the major isomer the CH2 group lies trans to the C6F5 group both in solution and in the crystal. In the minor isomer the CH2 lies cis to the C6F5 group....

Reaction of hexafluorobenzene with Ni(COD)2 (COD = 1,5,-cyclooctadiene) in the presence of triethylphosphine or with Ni(PEt3)4 at room temperature results in very slow formation of trans-Ni(PEt3)2(C6F5)F (1). The X-ray crystal structure reveals a molecular complex with approximately square-planar coordination at nickel, a Ni−F distance of 1.836(5)...

Photolysis of [Re(η 5 -C 5 H 4 R)(CO) 3 ] (R = H or Me) in hexafluorobenzene yielded [Re(η 5 -C 5 H 4 R)(CO) 2 ( η 2 -C 6 F 6 )] containing the η 2 -co-ordinated arene. The complex containing η 5 -C 5 H 5 has been characterised crystallographically. It forms monoclinic crystals in space group P2 1 /n with Z = 4, a = 7.926(2), b = 12.179(4), c = 13....

Photolysis of [Re(η5-C5H4R)(CO)3] (R = H or Me) in hexafluorobenzene yielded [Re(η5-C5H4R)(CO)2(η 2-C6F6)] containing the η2-co-ordinated arene. The complex containing η2-C5H5 has been characterised crystallographically. It forms monoclinic crystals in space group P21ln with Z = 4, a = 7.926(2), b = 12.179(4), c = 13.675(4) Å and β = 102.91(2)°. Th...

Thesis (Ph. D.)--University of York, 1998.