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Abstract Korean hand papermaking is a renowned cultural tradition in the Korean peninsula. It is still practiced while scientific analysis of paper itself from a large data set is rare. In this study, a set of more than three hundred Korean handmade papers, collected in a reference collection book Hanji: Korean handmade paper, were chemically investigated, and their property data such as colour, pH, grammage, thickness, tensile strength, folding endurance were statistically analysed in order to determine general features for Korean papers. The influence of different paper sheet formation methods (Heullimtteugi vs Gadumtteugi) were revealed by multivariate data analysis and the chemical profiles of raw materials were studied by pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS). The Korean handmade paper samples display colour gamut in the colour space L* (69.9–95.9), a* [(−3)-3], b* (0–20), most have neutral/alkaline pH values. Paper density, fiber orientation and physical properties are influenced by the sheet formation techniques. For instance, Gadumtteugi tends to produce papers with strong fiber orientation while Heullimtteugi produces papers with more evenly distribution of fibers. In addition, Py-GC/MS analysis results show that paper mulberry fibers contain less intensity lignin monomers and more terpenic compounds in comparison with gampi and mitsumata fibers. This study provides paper analysis from large sample set, statistics reveal that the material preparing and making craft determined the paper structure which reflected in their physical properties. These properties influenced paper performance and applications in art creations as well as relics conservation and restoration. The characterized paper sample database could be used for handmade paper studies in East Asian region. Consequently, this study contributes to a better understanding of contemporary Hanji properties as well as improves knowledge on handmade papers from the Korean peninsula.

Abstract Natural yellow plant dyes and traditional medicines were used widely on historical papers in ancient China for religious reasons and conservation considerations. This study aims to evaluate some traditional yellow botanical sources of dyes that contain different chemical colorant compositions in order to understand their effects on the properties of traditional handmade paper. The physical and chemical changes in paper specimens treated with plant dyes were studied by examining properties such as the color, pH, thermogravimetric (TG) characteristics, tensile strength, folding endurance and microstructure by scanning electron microscopy (SEM). The results indicated that different colorants had different toning effects and that the main components, including carboxyl and ketone groups, could affect the paper stability at high temperatures. The results also revealed that the mechanical properties of paper specimens were improved after treatment with plant dyes. The significant improvements in the tensile strength and folding endurance and the slightly higher decomposition temperature of Amur cork tree-dyed paper could be ascribed to the strong interaction between the colorants’ main components and the fibers. The scientific evaluation of the property changes is therefore valuable information for weighing the advantages and disadvantages of the various yellow toning materials for paper conservation treatment.

Abstract Valvasor's library is a unique example of a Seventeenth century personal library, including over 7300 prints and 1530 books. Today, it is kept in the Metropolitan Library of the Zagreb Archdiocese which is part of the Croatian State Archives. In this study, we analysed a selection of papers from Valvasor's collection (VC) of unknown origin and composition. We used a dual approach, combining the results of the analyses of two sets of samples to find the most useful tools for the characterization of historical handmade papers. 144 randomly selected papers were included in the study. As the VC is a cultural heritage, only non-destructive analyses were used, such as visual inspection, surface imaging, measurements of thickness and the determination of optical properties (brightness, yellowness, opacity and gloss). According to the optical properties, papers from the VC could be characterized as yellowish and opaque, without gloss. Due to the fact that the VC papers could not be destroyed, we took another set of samples consisting of 10 historical papers (HP) from archival materials, dating from the 16th to nineteenth century, and subjected them to non-destructive, as well as micro-destructive analyses. This was done to supplement the findings of non-destructive analyses of the original collection. Initially, spot tests were performed to determine water absorbency and to identify the presence of lignin and starch in the paper samples. SEM–EDS and XRF were applied for the identification of inorganic elements. FTIR analyses were used to identify the chemical structures of the paper components. Microscopic analyses were performed in two ways: the paper surface was imaged with a digital microscope, and the morphological characteristics of the fibres were studied using an optical microscope. The dominant fibres present were flax and hemp, with a smaller proportion of cotton. Additionally, thick and thin light brown fibres resembling straw were detected. The presence of calcium-containing components, gelatine and alum could be confirmed with SEM–EDS, XFR and FTIR analysis. Comparing the results of analyses performed on two sets of samples a connection was explored by which it was possible to define the characterization of VC papers. The main goal of the study was to document and characterize a specific collection for the future use of researchers of handmade paper or paper conservators. Furthermore, the study may serve as a model approach for other researchers who seek to document the characteristics of paper in their collections.

Abstract An innovative survey was conducted of the collections of the historical Biblioteca Classense, located in the urban area of Ravenna (Northern Italy). The survey aimed to evaluate the current conservation state of the book collections, where 297 paper-based items, including incunabula, manuscripts and books, dating from the 14th to the 20th century, were selected for analysis. This innovative survey was carried out non-destructively by assessing degradation visually and by measuring NIR spectral data followed by multivariate data analysis. Chemical and physical paper properties, important for paper characterisation and implementation of conservation strategies were determined, including paper type, pH, degree of polymerisation (DP), tensile strength, lignin, protein, and rosin content. This survey provided a significant quantitative dataset for rag paper covering a 600-year period. The analysis of DP changes over time allowed the first experimental estimation of the rate constant for historical rag paper, i.e., (4.2 ± 0.6)·10−7 year−1, which was validated with predictions based on the Collections Demography dose response function for historic paper taking into account the past climate in Ravenna. Statistical methods were employed to describe the correlations between the measured variables and different features of the books, suggesting that the degree of polymerisation can be used as a general proxy for rag paper mechanical strength.

Abstract The coating technique, supposedly invented by Chinese papermakers no later than the 3rd century AD, greatly improved paper sheets’ qualities of color, texture, writability, and printability. Alongside the dispersal of papermaking and surface-treatment techniques beyond China, coated papers were manufactured and used in many other regions of the world. Understanding the manufacture of coated papers, therefore, is crucial for perceiving how surface treatments were developed to meet the need for paper with enhanced properties. However, the characterization of coating and coating pigments on ancient Chinese papers has long remained an unsolved issue, and previous studies on this topic have often produced inconclusive results. To explore a non-invasive methodology that can more reliably characterize coated papers and the coating pigment on them, this article presents the results of a pilot study that applied micro-computed tomography (micro-CT) and Raman spectroscopy to samples of three Qing Dynasty (1644–1911 AD) papers and two handmade papers manufactured in China in the 1990s. Micro-CT revealed the coating layer(s) on Lajian (waxed coated paper) and Lengjinjian (gold-dusted paper) of the Qing Dynasty and characterized the modern raw xuan and bamboo papers as uncoated. Raman spectroscopy, together with handheld X-ray fluorescence analysis, identified the mineral-based pigment in the coating layer, suggesting the use of lead white or kaolin as the coating pigment. Additionally, Raman analysis confirmed the use of other mineral pigments (red lead and cinnabar), beeswax, and organic dyes (gamboge, kermesic acid, and possibly purpurin) in the manufacture of Lajian and Lengjinjian papers. The combination of micro-CT and Raman spectroscopy, it is therefore suggested, is a practical, more reliable approach for non-invasive investigation of coating and coating pigments on ancient Chinese paper specimens.

Abstract The ancient technique employed to produce Lajian paper—a very famous Chinese traditional handmade paper—has been lost. However, widespread restoration of the traditional skills used in the paper’s production is emerging in China. A small piece of orange-red Lajian paper dating from the Qing dynasty and decorated with flecked Ag and Au was chosen as the subject of this study to investigate the paper’s composition and structure using optical microscopy (OM), SEM–EDS, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and FTIR spectroscopy. The results revealed that the raw materials constituting the Lajian paper were bast and bamboo fibers. Each of the two paper layers was treated differently. First, the upper orange-red layer was treated with kaolinite and organic turmeric. Next, inorganic minium nt was used to obtain an orange-red color. Animal glue was used as a binding medium. Finally, the dyed surface was waxed with Chinese insect wax and then polished with small stones to form a smooth coating. The same treatment, except for the intentional use of inorganic pigment, was applied to the backing layer. Turmeric dye, minium, and wax coating protected Lajian paper from humidity and mold growth while maintaining the stability of the paper.

Abstract Deacidification is an established conservation treatment for the prolongation of the acidic paper stability. Several different deacidification systems are in use today, such as the dispersions of alkaline nanoparticles in organic solvents. The aim of the study was to compare the effects of different calcium nanoparticle dispersions in alcohols on lignocellulosic paper. Commercially available nano calcium hydroxide dispersions for paper deacidification, and laboratory prepared nano calcium carbonate dispersions in ethanol and 2-propanol were investigated and compared as to their effectiveness in increasing the stability of paper. The FE-SEM analyses were used to determine the size of Ca(OH)2 and CaCO3 particles in the dispersions. The SEM–EDS analyses were performed both on the paper surface and its cross-section in order to ascertain the distribution of calcium ions following the deacidification treatment. An evaluation of the changes of color, molecular weight, pH and alkaline reserve on different lignocellulosic papers was performed. In comparison to untreated samples, our results indicate all the investigated deacidification treatments decrease the degradation rate constant of cellulose, as determined by accelerated degradation. However, the treatments involving nano calcium hydroxides in both alcohols noticeably affect the color of the treated lignocellulosic papers. According to the obtained results, nano calcium carbonate is therefore the more suitable deacidification agent for the lignin containing papers.

Korean hand papermaking is a renowned cultural tradition in the Korean peninsula. It is still practiced while scientific analysis of paper itself from a large data set is rare. In this study, a set of more than three hundred Korean handmade papers, collected in a reference collection book Hanji: Korean handmade paper, were chemically investigated, and their property data such as colour, pH, grammage, thickness, tensile strength, folding endurance were statistically analysed in order to determine general features for Korean papers. The influence of different paper sheet formation methods (Heullimtteugi vs Gadumtteugi) were revealed by multivariate data analysis and the chemical profiles of raw materials were studied by pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS). The Korean handmade paper samples display colour gamut in the colour space L* (69.9–95.9), a* [(−3)-3], b* (0–20), most have neutral/alkaline pH values. Paper density, fiber orientation and physical properties are influenced by the sheet formation techniques. For instance, Gadumtteugi tends to produce papers with strong fiber orientation while Heullimtteugi produces papers with more evenly distribution of fibers. In addition, Py-GC/MS analysis results show that paper mulberry fibers contain less intensity lignin monomers and more terpenic compounds in comparison with gampi and mitsumata fibers. This study provides paper analysis from large sample set, statistics reveal that the material preparing and making craft determined the paper structure which reflected in their physical properties. These properties influenced paper performance and applications in art creations as well as relics conservation and restoration. The characterized paper sample database could be used for handmade paper studies in East Asian region. Consequently, this study contributes to a better understanding of contemporary Hanji properties as well as improves knowledge on handmade papers from the Korean peninsula. [ABSTRACT FROM AUTHOR]

Abstract The study of micro-objects, both inorganic and organic, which can be found associated to parchment or cellulose fibres of books and documents, or in the inks and the dirt, accumulated over the centuries between the pages, can unravel important information on the manufacture of the ancient documents, on their past vicissitudes or on the causes of aging and deterioration of the materials they contain. The results of a critical observation of micrometric objects and structures with a diagnostic or archaeological significance have in some cases been surprising. Apart from the curiosity that certain findings may or may not raise, what needs to be discussed is the fact that some chemical components, usually attributed to the manufacture of materials or the inks may instead have a particular origin and nature, and therefore lead, if not properly highlighted, to some erroneous diagnostics. Examples are given where the information obtained by means of scanning electron microscope imaging and Raman microscopy were coupled with dispersive X-ray microanalysis and Fourier Transform Infrared Spectroscopy.

Abstract A scrapbook compiled between 1660 and 1687 by Gesina ter Borch (1631–1690), a female artist from the small town of Zwolle in the Netherlands, contains an intriguing painting on paper of a full-length portrait of a young Iranian. Although the figure wears the attributes in vogue at the Safavid court of Isfahan, certain elements seem rather incongruous and peculiar. The general composition appears static and rigid, an impression reinforced by an unusual black painted background. Stylistic differences within the painting were also observed, hinting at alterations to the original painting. To investigate the history of the painting and to reconstruct the original composition and identify the later additions, perhaps made by Gesina herself, the painting was examined with different imaging and analytic techniques available at the Conservation and Science Department of the Rijksmuseum. This allowed the research team to discriminate between pigments used for the original composition and pigments used to conceal damaged areas of the painting and added pictorial elements. After interpreting scientific results, as well as historical findings, it was possible to shed light on the use of specific pigments, namely lead white and smalt, and on the possible misinterpretation of some details, such as the cup held by the young man. The results of macro X-ray fluorescence scanning (MA-XRF) and lead isotope analysis, viewed in the light of information about the economic and cultural exchanges between Iran and the Netherlands in the seventeenth century, fed new theories about the origin and history of this painting. The painting, originally made in Iran in the style of Riza Abbasi, the head of the Emperor Shah Abbas’ library, ended up in Gesina ter Borch's workshop and may have been ‘restored’ by the artist to improve its condition and to match her tastes.

There are many paper manuscripts at museums, stores, and libraries that have different stains. The dust stains and soil remains played an important role in the degradation of these manuscripts. Therefore, the cleaning process for these stains is important to process. Unfortunately, the removal of stains by some traditional techniques can be hazardous to the paper's fibers. Therefore, this study aims to evaluate innovative nanoparticle gels in the cleaning process of dust stains from paper manuscripts. The synthesized nanomaterials [Fe3O4, TiO2, and ZnO]/Carbopol hybrid nanogel were examined in order to investigate the surface morphology, determine the physio-chemical properties, for phase structure, using scanning electron microscope (SEM), transmission electron microscope (TEM), AFM, DLS, XRD, and Zeta potential. Some stained paper samples were prepared and exposed to accelerated thermal aging at 100 °C for 72 h. The evaluation of the cleaning by nanogel was performed by different analytical procedures containing investigation with a USB digital microscope, SEM, color change, mechanical properties, and ATR-FTIR analysis. The results of this study showed that ZnO/Carbopol hybrid nanogel at high viscosity gave the best results in the cleaning process of mud stains through the ability to dismantle mud particles and increase surface contact with the solvent. The aged treated sample with high viscosity form of ZnO NPs/carbopol hybrid nanogel gave the highest tensile strength value of (56.0 N). The treated samples with the high viscosity form of ZnO NPs/carbopol hybrid nanogel gave the highest value of elongation (1.398%) before aging. It also does not affect the chemical composition of the paper after cleaning it, but rather on the whole, it bites the hydration of the paper, which positively affects the properties of the treated paper. [ABSTRACT FROM AUTHOR]

Abstract Historical papers are often locally damaged by exogenous influences and/or have endogenously degraded paper areas. The stabilization of such papers is very important because further use of the object can cause additional damage. Different types of nanocellulose are interesting as a novel stabilizing materials for paper due to their close structural relation to the paper matrix. Therefore, the present study investigated whether the treatment of historical papers with nanocellulose suspensions is a novel method for paper stabilization. Two different types of nanocelluloses, bacterial cellulose and a mechanically nanofibrillated cellulose based on wood pulp, were tested with regard to their performance in stabilizing fragile papers. Concerning material handling and application in conservation steps, different ways to modify the suspensions were tested. The resulting suspensions were applied to historical papers from several centuries with different extents of damage. The paper-nanocellulose composites were characterized with regard to their optical and microscopic integrity and by physical and chemical analyses. The treatment of mechanical damage and the consolidation of weakened paper areas could be realized by the application of a nanocellulose suspension without an additional adhesive. The results of the treatment depend on the type of nanocellulose, on the paper material, on processing and application techniques. The paper discusses the applicability and stability of the differently prepared nanocellulose suspensions, also with regard to their mode of application and long-term performance. Advantages and limitations are addressed in detail. Graphical abstract Bacterial nanocellulose and nano-fibrillated cellulose from pulp can be used to consolidate damaged historic papers without the application of additional adhesives

Abstract Because of its acidic and oxidative nature, iron gall ink promotes the endogenous degradation of paper manuscripts. Mechanical damage in areas of concentrated ink application or along mechanically stressed edges or folds results in problems during storage and handling. So far, such strongly degraded areas have usually been stabilized locally with thin Japanese paper and adhesives. A new and innovative material—nanocellulose—is being evaluated as a stabilizer for manuscripts that have been degraded by iron gall ink. The aim of this study is to integrate the nanocellulose application into a multi-stage calcium phytate/calcium hydrogencarbonate treatment to combine deacidification and stabilization, thus avoiding an additional stabilization and drying step. Two different types of fibrillated nanocelluloses were applied on manuscripts damaged by iron gall inks in different treatment steps. The newly formed, interlinked network of nanocellulose and paper was characterised before and after accelerated degradation in closed vials. The effects on the paper cellulose were studied by size exclusion chromatography and light scattering with carbonyl group profiling to follow cellulose hydrolysis and oxidation pathways. In addition, the migration behavior of iron ions was examined by laser ablation coupled with metal analysis (ICP-MS). This paper discusses the applicability and stability of nanocellulose on paper damaged by iron gall ink with regard to its long-term performance. Advantages and limitations are covered in detail.

The chemical and physical properties of 19th and 20th century Chinese papers were investigated using a variety of material characterisation methods. A reference collection of 178 Chinese papers, dating from 1799 to 1990 was used, and properties such as pH, degree of polymerisation (DP), lignin content, and tensile strength (zero-span) were determined. Most of the papers were of approximately neutral pH, had a low lignin content and DP similar to pre-19th century European rag paper. It was found that the high inhomogeneity and the typical paper thinness affected tensile testing and as a result, a modified method for zero-span tensile strength test was developed. Using near infrared spectroscopy (NIR), proof-of-concept partial least squares (PLS) applications were developed for determination of tensile strength, pH, DP and for dating of the samples. For the latter, using post-1900 papers, the error of cross validation was 13 years. The presence of lignin was modelled using linear discriminant analysis (LDA), where the model could distinguish between high and low lignin content with 88% accuracy. Using one or multiple sheets for transmission NIR spectroscopy led to PLS results of similar quality, which was attributed to material inhomogeneity. [ABSTRACT FROM AUTHOR]

In the restoration of ancient Chinese books, handmade starch paste serves as a paper adhesive, distinguished from traditional starch paste preparation methods. It involves special processes such as starch washing and aging, relying entirely on the artisanal expertise throughout the entire process. The study recreates the process of making handmade starch paste for the restoration of traditional ancient books and investigates the effects of aging time on the apparent viscosity, rheological properties, and adhesive performance of the paste. The results indicate that during aging, the pH of the starch paste decreases significantly, but it has a minimal impact on its apparent viscosity, rheological properties, and paper softness. However, it notably enhances the adhesive performance, with the optimal results observed after 3 days of aging. This is attributed to the decrease in residual protein content in the starch, as well as the significant improvement in swelling power and solubility of the starch. The results of infrared spectroscopy and XRD testing reveal that there are no significant changes in the molecular and crystalline structures of starch during the aging process. The acidic environment produced by starch fermentation promotes protein hydrolysis, emerging as the primary reason for the improved adhesive performance of the paste. [ABSTRACT FROM AUTHOR]

Abstract Folk contract documents (FCD) are valuable materials for studying social history, and the paper they use reflects the social realities of different eras and social classes. Research and scientific analysis of numerous FCD samples after the fourteenth century are rare. We conducted a study on 96 Tianshui folk contract documents (TFCD, 107 paper samples) from the Tianshui area of Gansu Province, Northwest China, taking into account both the textual content and the materiality of paper carriers, and interpreted the results from multiple lines of evidence and discussion. Physical performance analysis revealed that the paper used by the northern folk exhibits a lower apparent density, which is not conducive to the long-term preservation of paper. The preservation status investigation, curtain pattern analysis, and fiber analysis show that the paper used in the TFCD differs from traditional cultural paper regarding disease types, production precision, and fiber materials, providing a basis for its protection and restoration. The analysis of chemical components indicated that the aging and yellowing of paper can be correlated with the content of sulfur and carbonyl groups. The feasibility of using pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) analysis to quickly identify papermaking fibers in a large number of paper samples was proposed. By utilizing various techniques to inspect the paper of documents, this study helps to enhance the academic understanding of FCD materials. In addition, it expands the knowledge base of Northwest handmade paper.

Abstract The chemical and physical properties of 19th and 20th century Chinese papers were investigated using a variety of material characterisation methods. A reference collection of 178 Chinese papers, dating from 1799 to 1990 was used, and properties such as pH, degree of polymerisation (DP), lignin content, and tensile strength (zero-span) were determined. Most of the papers were of approximately neutral pH, had a low lignin content and DP similar to pre-19th century European rag paper. It was found that the high inhomogeneity and the typical paper thinness affected tensile testing and as a result, a modified method for zero-span tensile strength test was developed. Using near infrared spectroscopy (NIR), proof-of-concept partial least squares (PLS) applications were developed for determination of tensile strength, pH, DP and for dating of the samples. For the latter, using post-1900 papers, the error of cross validation was 13 years. The presence of lignin was modelled using linear discriminant analysis (LDA), where the model could distinguish between high and low lignin content with 88% accuracy. Using one or multiple sheets for transmission NIR spectroscopy led to PLS results of similar quality, which was attributed to material inhomogeneity.

Abstract Prior studies have shown the improved ability to identify artists’ pigments by combining results from X-ray fluorescence (XRF), which provides elemental information, with reflectance spectroscopy in the visible to near infrared (400–1000 nm) that provides information on electronic transitions. Extending the spectral range of reflectance spectroscopy into the UV, 350–400 nm, allows identification of several white pigments since their electronic transitions occur in this region (e.g., zinc white and rutile and anatase forms of titanium white). Extending the range further into the infrared, out to 2500 nm, provides information on vibrational transitions of various functional groups, such as hydroxyl, carbonate, and methyl groups. This allows better identification of mineral-based pigments and some paint binders. The combination of elemental information with electronic and vibrational transitions provides a more robust method to identify artists’ materials in situ. The collection of both sets of spectral information across works of art, such as paintings and works on paper, allows generating a more complete map of artists’ materials. Here, we describe a 2-D scanner that simultaneously collects XRF spectra and reflectance spectra from 350 to 2500 nm across the surfaces of works of art. The scanner consists of a stationary, single pixel XRF spectrometer and fiber optic reflectance spectrometer along with a 2-D position-controlled easel that moves the artwork in front of the two detection systems. The dual-mode scanner has been tested on a variety of works of art from illuminated manuscripts (0.1 × 0.1 m2) to paintings as large as 1.7 × 1.9 m2. The scanner is described and two sets of results are presented. The first is the XRF scanning of a large warped panel painting by Andrea del Sarto titled Charity. The second is a combined XRF and reflectance scan of Georges Seurat’s painting titled Haymakers at Montfermeil. The XRF was collected at 1 mm spatial sampling and the reflectance spectral data at 3 mm. Combining the results from the data sets was found to enhance the identification of pigments as well as yield distribution maps, in spite of the relatively low reflectance spatial sampling. The elemental and reflectance maps allowed the identification and mapping of lead white, cobalt blue, viridian, ochres, and likely chrome yellow. The maps also provide information on the mixing of pigments. While the reflectance image cube has 10–20× larger spatial samples than desired, the elimination of having to use two hyperspectral cameras to cover the range from 400 to 2500 nm makes for a low cost dual modality scanner.

Knowledge of salt and moisture distribution is a key factor for understanding rock decay at cultural heritage sites. The cave town of Uplistsikhe in Georgia, carved from sandstone in late bronze age to medieval times, suffers from progressive scaling and flaking processes. Multi-method investigations of rock moisture and salt distribution were carried out in order to better understand the patterns of decay. Salt distribution was investigated using drill dust samples and paper pulp poultices; moisture was determined by 2D-resistivity and handheld microwave sensors, supplemented by infrared thermography. The combined results from the different methods revealed a complex pattern of salt and moisture distribution. At most sites, K2SO4 (arcanite) and its hydrates dominate, sometimes in combination with CaSO4 (gypsum). At one site (Grandhall), halite (NaCl) and niter (KNO3) prevail. Sulphates are assumed to be a legacy of air pollution; origin of halite and niter remains unsolved but might be due to concrete reinforcements. Two main sources of moisture were evidenced depending on season and spatial situation: (1) Condensation of air humidity at cool cave backwalls in spring (combined with and aided by salt hygroscopicity), evidenced by 2D-resistivity and infrared thermography; (2) seepage along joints particularly at the cave backwalls and roofs, evidenced by handheld microwave sensors. Further investigations should focus on identifying seepage pathways and on clarifying the origin of destructive halite and nitrates. [ABSTRACT FROM AUTHOR]

Abstract Background Infrared reflectography (IRR) remains an important method to visualize underdrawing and compositional changes in paintings. Older IRR camera systems are being replaced with near-infrared cameras consisting of room temperature infrared detector arrays made out of indium gallium arsenide (InGaAs) that operate over the spectral range of ~900 to 1700 nm. Two camera types are becoming prevalent. The first is staring array infrared cameras having 0.25–1 Megapixels where the camera or painting is moved to acquire tens of individual images that are later mosaicked together to create the infrared reflectogram. The second camera type is scanning back cameras in which a small InGaAs array (linear or area array) is mechanically scanned over a large image formed by the camera lens to create the reflectogram, typically 16 Megapixels. Both systems have advantages and disadvantages. The staring IR array cameras offer more flexible collection formats, provide live images, and allow for the use of spectral bandpass filters that can provide reflectograms with better contrast in some cases. They do require a mechanical system for moving the camera or the artwork and post-capture image mosaicking. Scanning back cameras eliminate or reduce the amount of mosaicking and movement of the camera, however the need to minimize light exposure to the artwork requires short integration times, and thus limits the use of spectral bandpass filters. In general, InGaAs cameras are not sensitive in the 1700 to ~2300 nm spectral region, which has been identified in prior studies as useful for examining paintings with copper green pigments or thick lead white paints. Prior studies using cameras with sensitivity from 1000 to 2500 nm have found in general the performance at wavelengths longer than 1700 nm degraded relative to the performance at shorter wavelengths. Thus, there is interest in a camera system having improved performance out to 2500 nm that can utilize spectral bandpass filters. Methods Design requirements for such an improved IRR camera system were determined by first re-examining the optimal spectral window for detecting underdrawing. Thus the wavelength dependence of the clarity of carbon black underdrawings on a chalk ground covered by various paint swatches was measured from 750 to 2500 nm. Second, analysis of the loss of light transmission (1000–2500 nm) and the impact of thermal radiation (3000–5000 nm) on the performance of IR arrays sensitive to the 1000–5000 nm region was analyzed. From the results of these studies, a high sensitivity, near-infrared (1000–2450 nm) indium antimonide (InSb) staring array camera with a cold filter that blocked light >2450 nm was constructed with a color-corrected macro lens capable of holding interference filters. The camera system was characterized in three spectral bands (1100–1400, 1500–1800, and 2100–2400 nm) using test targets and art objects. Results The experimental results of the contrast difference between the model underdrawing on the chalk ground showed the optimal spectral window for a given pigment varied over the range from 700 to 2300 nm. The contrast in all cases was found to be low from 2300 to 2600 nm and even lower from 2600 to 5000 nm. This is attributable in part to broad absorption by the drying oil paint binder. Performance testing of the IRR camera found high signal-to-noise was observed in all three spectral bands due to the optimized macro lens having high transmission from 1000 to 2600 nm, a 100% efficiency cold stop, and a cold filter that blocks light >2450 nm. The camera was found to have high light sensitivity, requiring only ~30 to 50 lx from incandescent lamps having a color temperature of ~2060 K. The images produced in each spectral band were sharp, and the modulation at Nyquist (1/2 the sampling frequency) was 20%. IRR images of Old Master paintings, works on paper, and a warped panel painting were collected to test the practical utility of the camera system. Conclusions The IR camera system presented here was found to produce a variety of high-resolution image products. The ability to extend image collection over the 1700–2450 nm spectral range was found in some examples to provide improved visibility of underdrawing. The ability to register the resulting multi-band IRR images with the color image offers opportunities to produce new image products such as false-color images and principal component images. These image products were found to give new insights into the construction of works of art. A collection scheme based on a ‘Z-stack’ method was found to solve the problem of producing high-resolution IRR images of highly warped panel paintings.

The fossils of Hamipterus tianshanensis (Wang et al. in Curr Biol 24:1323–1330, 2014) and their eggs have important scientific significance because they can provide unique information about the reproduction, development, and evolution of pterosaurs. The fossils and the rock surrounding them have, however, been weathered, which including powdering and flaking, since they were relocated from Xinjiang to Beijing. The high content of soluble salts is a significant factor in fossil deterioration because the dissolution–recrystallization process can generate tremendous pressure and lead to decreased mechanical strength. This study evaluated the electrokinetic desalination performance for the fossils, and two types of poultices employed including paper pulp from Bioline® and CKS121 (cellulose: kaolin: sand = 1:2:1, w/w). Mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), ion chromatography (IC), and other methods were applied to evaluate the desalination effect. The surface salt content reduction by applied direct current (DC) was about 70%, and the inner salt content reduction was about 80%. The experimental results suggest that the electrokinetic method is a promising way to desalinate fossils. Nonetheless, cracks appeared in the surrounding rock crack after electrokinetic desalination, which can be explained by the montmorillonite swelling-induced stresses. Pre-consolidation, especially for electro-chemical method may solve the cracking problem for the clay-rich sandstone desalination. [ABSTRACT FROM AUTHOR]

Abstract This paper presents the use of X-ray computed tomography and X-ray fluorescence in the analysis and expert research of the seventeenth century printed book "Eukhologīon albo Molitoslov, ili Trebnik" from Kiev. The main purpose of the survey was to confirm whether the book binding is original or whether it is a rebinding, and whether there are any fragments of the hidden older texts. Commonly used radiography is usually not able to provide sufficient information for these purposes. On the other hand, computed tomography allows a detailed and three-dimensional documentation of the bookbinding technology and the structure of the materials used, including the wooden boards. It will be presented that all elements of the weave are clearly visible, making it possible to show that there are no internal defects in the stitching and materials. It has also been convincingly shown that there are no fragments or layers of older texts in the binding, so no further invasive intervention will be necessary regarding this aspect. The paper also demonstrates the possibility of reading the text in a closed book utilising X-ray computed tomography data; this option may be advantageous for massively damaged manuscripts. It will also be shown, that thanks to detailed tomographic imaging of the wood structure of the boards, a dendrochronological survey can be successfully carried out without invasive intervention into their outer layers. From the CT data it was also found that the pigments of the letters have significantly different densities. Therefore, as part of the survey, elemental analysis of the writing was also carried out using a portable X-ray fluorescence spectrometer to confirm and clarify this finding.