Search Results (237)

Ironing is an effective process for precisely finishing a formed product at the final stage of a series of forming processes. Generally, a high-performance lubricant oil with high viscosity is used to prevent galling under severe forming conditions, but high-viscosity oil is difficult to remove from the workpiece after the forming process. Residual oil can interfere with subsequent processes such as welding, heat treatment, and painting. Therefore, low-viscosity oils with excellent cleanability are desirable under severe ironing conditions. In this study, differential lubrication was applied to ironing to enable the use of low-viscosity lubricant oil. The results showed that severe galling occurred on the inner surface of the workpiece when a low-viscosity oil was used. However, no galling was observed when low- and high-viscosity oils were applied to the inner and outer surfaces of the workpiece, respectively. These results indicate that differential lubrication enables the use of a low-viscosity lubricant oil without galling while maintaining high surface quality. Full article

Four unvarnished oil paintings by the abstract expressionist artist Joan Mitchell were studied and conserved at the Carnegie Museum of Art (CMOA) and the Indianapolis Museum of Art at Newfields (IMA). These paintings, Sans Neige, Sans Neige II, Low Water, and Diabolo (neige et fleurs), all dating to 1969, share a similar color palette and degradation phenomenon in thickly applied cadmium yellow brushstrokes. Samples from three works were studied using Raman and FTIR spectroscopies, stereo microscopy, and scanning electron microscopy with energy dispersive spectrometry. A protocol was developed at CMOA for the consolidation of the crumbling yellow matte impasto through the careful application of funori with gentle manipulation of the paint. Acrylic fills were used to mimic Mitchell’s paint handling in areas of loss, and the fills were textured and inpainted using funori with ground original paint samples that had detached and could not be reattached to the painting’s surface. The treatment was successfully repeated at the IMA through online collaboration with CMOA during the COVID-19 pandemic. Samples were analyzed to identify, for the first time, the artist’s late 1960s palette. Waxy nodules observed in cross sections of the crumbling yellow paint were determined to be zinc stearate agglomerates, focused along break edges and incipient cracks, strongly suggesting a relationship between the instability of the paint and these zinc soaps. Full article

This research provides new insights into the materials, methods of application and modification of the black lines used by Piet Mondrian (1872–1944) in his Neoplastic works. Interesting information was gained from letters and studio photographs, the making of mock-ups and reconstructions, and the in-depth study of four paintings, dated between 1921 and 1938, in the collection of Fondation Beyeler (Riehen/Basel, Switzerland)—Tableau I (1921–1925), Composition with yellow and blue (1932), Composition with double line and blue (1935) and Picture no. III (1938)—as well as the examination of an unfinished painting, Composition with red (1934, private collection). The four paintings were investigated with high-magnification stereomicroscopy, technical photography in transmitted light and raking light, X-rays and infrared reflectography. Detailed information about the buildup and composition of the layers was gathered with the study of cross sections and microsamples, using optical microscopy and chemical analyses. It was shown that Mondrian frequently moved the lines and changed their width up to the very last working phase and, probably, did not use a ruler in the traditional sense to achieve straight lines. In one of the works, Mondrian even employed a pencil, tracing a groove in the wet paint to accentuate straight edges. The black lines consist of multiple paint layers of diluted bone black oil paint, added with small amounts of coloured paint, alternated with thin oil-resin layers, sometimes containing lead white particles. Finally, a thin (pigmented) oil-resin finish was applied on top of the black line. Full article

Modern oil paintings are characterized by the extensive use of industrial pigments, synthetic binders, and chemical additives introduced during the late nineteenth and twentieth centuries. While these innovations enabled significant artistic experimentation, they also introduced new conservation challenges due to the chemical instability of many modern paint formulations. As a consequence, modern oil paintings frequently exhibit degradation phenomena such as efflorescence, yellowing, blistering, peeling and cracking, and high sensitivity to water and organic solvents. A comprehensive understanding of the materials used in modern oil paintings—including pigments, binders, and additives—is therefore essential for developing effective conservation strategies. In this context, electromagnetic (EM) diagnostic techniques represent powerful tools for the noninvasive or minimally invasive investigation of artworks. These techniques allow researchers to characterize the chemical composition, morphology, and degradation processes affecting paint layers and substrates. This paper provides an overview of the EM techniques most commonly used in the conservation of modern oil paintings. Particular attention is devoted to spectroscopic and imaging methods such as scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, UV-Vis spectroscopy, and X-ray-based techniques, as well as to the laser technique for the delicate cleaning process. Through selected case studies reported in the literature, this review highlights the role of these techniques in pigment identification, degradation analysis, and the development of more effective conservation strategies for modern oil paintings. Full article

Oil paintings, sketches, and printed works on paper frequently exhibit characteristic forms of deterioration caused by the absorption of linseed oil binders into the paper substrate. This study investigates for the first time the factors influencing the resulting volatile organic compound (VOC) emissions from oil-impregnated papers upon ageing and explores VOC quantifiable metrics suitable for condition assessment. Headspace Solid-Phase Microextraction coupled with Gas Chromatography-Mass Spectrometry (HS-SPME–GC-MS) was employed to sample and analyse VOCs from mock-ups made of three types of paper (a pure cellulosic, lignin-free and lignin-containing lignocellulosic papers with alkaline buffer), three pure linseed oil formulations (cold-pressed and alkaline-refined linseed oil, and stand oil), and oil-impregnated paper mock-ups, all subjected to controlled artificial ageing. The results showed a clear difference in VOC profile emissions between pure papers and linseed oil formulations, while oil-impregnated mock-ups emitted compounds matching those of the linseed oil formulations; however, the emissions followed a different trend. Statistical analysis (PCA) demonstrated that both paper pulp content and oil formulation significantly influence VOC emission patterns, highlighting the compounds that produce higher and most characteristic emissions. Ratios of specific compounds—such as formic to acetic acid—showed consistent trends across materials, indicating their potential as markers for distinguishing stages of deterioration. Full article

In this paper, we present the result of the study conducted on aging tests carried out by the artist Emile Claus (1849–1924), composed of oil paint samples from three manufacturers: Blockx, Lefranc Bourgeois and Fritz Behrendt. These colors were applied neat and mixed with white on wooden panels prepared with white ground layer. A non-invasive analytical protocol, combining imaging techniques and physico-chemical analyses, was used to characterize potential differences between manufacturers for nominally identical colors. The differences highlight in this study include variations in nickel content in cobalt blue colors and aluminum content in madder lakes. It also discusses the intrinsic and extrinsic factors that led to the degradation of certain colors. Hyperspectral imaging further demonstrated that the addition of lead white induces a systematic shift of spectral inflection points toward shorter wavelengths, consistent with the optical dilution effect in pigment-white mixtures, while the altered colors do not follow the same trend. Full article

Removing altered varnishes and retouching from oil paintings is a delicate and irreversible procedure in the conservation of cultural heritage. Surfactant-free gelled o/w emulsions containing dibasic esters (DBE) provide a green, safe, and environmentally friendly alternative to traditional solvent methods. The use of Xanthan gum and polyacrylate as thickening agents successfully restricted solvent diffusion, thereby minimizing the risk of interaction with water-sensitive substrates. Spectroscopic and microscopic analyses (FTIR and SEM) were employed to evaluate the cleaning efficacy and to assess the morphological integrity of the paint surface post-treatment, detecting potential inhomogeneities, erosion, or pigment loss. Determination of surface conductivity has allowed us to verify the degree of removal of any residues that could have undesirable long-term effects. Fatty acid leaching was quantified by gas chromatography-mass spectrometry (GC/MS): the use of free DBE resulted in a loss of up to 60% of the lipid component, while for surfactant-free gelled o/w emulsions with DBE, this figure was significantly reduced, with no observable surface damage. The tests were performed at both neutral pH and pH 8.5. The pH change was consistent with expected values: alkaline and ionizing conditions enhanced the emulsifying and removal effect, as well as the interaction with the painting medium. These results suggest that surfactant-free gelled o/w emulsions represent a promising alternative to conventional solvent-based systems, offering effective varnish removal while minimizing risks to both artifacts and restorers. Full article

Radiocarbon dating of lead white has progressed considerably in the last decade. Today, the protocol enables the analysis of various types of samples: pure lead white in cosmetics, ancient and modern paint layers containing lead white and oil, and mixtures of lead white and calcite. However, it has also been shown that the presence of a large amount of calcite in lead white paint can alter the radiocarbon result through contamination with dead carbon. To overcome this problem, careful characterization of samples must be carried out prior to dating. Lead white paint layers from the Queen’s apartment at the Palace of Versailles were observed by electronic microscopy and analyzed by Synchrotron X-ray-based diffraction to discriminate the different layers of paint in order to minimize contamination. Chemical analysis and ¹⁴C dating were used to document the implementation of the decorations in Queen Marie-Antoinette’s library. Full article

Iron Age settlements in the Salento peninsula (Southern Italy, 8th–6th century BC) underwent fundamental transformations in social organization, marked by the emergence of local elites through trade development and intense contacts with the Greek world. This study examines organic residue assemblages from 99 ceramic sherds from one key Iron Age site to clarify the role of locally produced ceramics—both coarse ware containers and Japigian matt-painted vessels—in commensal and beverage production practices. Chromatographic analyses identified a wide variety of animal and plant by-products, including fats, oils, waxes, and resin compounds. Integrated phytolith and starch analysis revealed evidence consistent with fermentation processes, particularly through the identification of fungal remains and damaged starch granules suggesting brewing activities in a subset of vessels. Matt-painted pottery forms—characterized by conical rims, funnel-shaped necks, bowls, and jugs—show distinctive use-alteration patterns and residue profiles associated with fermented beverage consumption and preparation in approximately 26% of the analyzed assemblage. Integrating organic residue analysis, experimental archaeology, and microfossil investigation suggests the central role of locally produced pottery in Iron Age commensal activities and status display, though alternative interpretations for some biomarker profiles cannot be excluded. This multiproxy approach demonstrates functional differentiation and consumption practices, refining interpretations of vessel use and providing new insights into food economies and social life during the Iron Age in southern Italy. Full article

Biofouling, the formation of a biofilm on submerged surfaces, is a widespread problem affecting all of the maritime industries and ecosystems. Historically, antifouling solutions have included toxic compounds, such as heavy metals and tributyl tin. Recently, less-toxic antifouling paints have been explored, including paints made from antioxidant-rich plants, and a study measured the effectiveness of polymer blends containing Aronia mitschurinii extracts. This new study will compare those results with polymer blends made from extracts of juvenile ginger and holy basil, two plants rich in antioxidants and essential oils. Extracts were assessed for antioxidant and essential oil content. Then, slides coated with a polymer-extract blend were exposed to freshwater and saltwater for three weeks and assessed by contrast microscopy. For freshwater and saltwater analysis, holy basil extracts had a minimum precipitation count of 3.40 ± 0.4 and 22.4 ± 6.0 for non-stained slides and 58.3 ± 7.3 and 9.3 ± 1.0 for stained. Ginger extracts had a minimum precipitation count of 3.9 ± 0.8 and 87.1 ± 17.3 for non-stained slides, and 5.4 ± 1.8 and 9.5 ± 0.3 for stained slides. All minimum precipitation counts for ginger and holy basil were less than those measured by controls and Aronia mitschurinii, showcasing the antifouling potential of ginger and holy basil extracts at a compatible but slightly lower level, but one that is much higher than was reported for other plant materials. Full article

This study investigates water-based gel and gel-like cleaning treatments on Superficie 553, an oil painting on canvas by Giuseppe Capogrossi, using portable NMR to assess their impact. The objective was to evaluate the effects of four cleaning systems composed of a buffer solution released in free form and combined with xanthan gum, a cross-linked silicone polymer gel, and an agar gel matrix. Two distinct NMR experiments were conducted. The first involved the acquisition of ¹H depth profiles to detect the distribution of the cleaning solution within the painted layer and the thickness variations resulting from cleaning procedures. The second employed the acquisition of relaxation times, facilitating the investigation of molecular mobility within the organic components of the paint layer. NMR results indicated that the agar gel system caused negligible structural changes, whereas the silicone gel induced rigidification, and the other systems permanently increased molecular mobility. These measurements provided insights into alterations in the dynamic behavior of the polymerized oil. A key strength of this investigation lies in the direct application of diagnostic methods on Superficie 553, made possible by the non-invasive nature and portability of the NMR-MOUSE system. Additionally, portable FTIR was used to detect residues and obtain chemical information, confirming that the silicone gel left detectable residues and identifying the agar gel as the most conservative cleaning method. This enabled in situ analysis of the original artwork without sampling or relocation—a crucial advantage given the difficulty of replicating the complex physicochemical conditions of historical paint surfaces under laboratory constraints. Such real-time, on-site monitoring ensured an authentic evaluation of the treatment effects, preserving the integrity of the artwork throughout the conservation process. Full article

Three painted valuable wood sculptures from conventual collections in Apulia (Southern Italy), made between the beginning of the 17th century and the first half of the 18th century, were studied to shed light on the pictorial materials and techniques of the Neapolitan Baroque sculpture in Southern Italy. A multi-analytical approach was implemented using integrated micro-invasive techniques, including polarized light microscopy (PLM) in ultraviolet (UV) and visible (VIS) light, scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), Fourier-Transform Infrared (FTIR) spectroscopy, and pyrolysis–gas chromatography/high-resolution mass spectrometry (Py-GC/HRMS). The stratigraphic sequences were microscopically identified, and the pictorial layers were discriminated on the basis of optical features, elemental compositions, and mapping. Organic components were detected by FTIR as lipids and proteinaceous compounds for binders, while terpenic resins were detected as varnishes. Accordingly, PY-GC/HRMS identified siccative oils, animal glue, egg, and colophony. The results allowed the identification of the painting techniques used for the pictorial films and the ground preparation layers and supported the distinction between original and repainting layers. The results of this multi-analytical approach provide insights into Baroque wooden sculpture in Southern Italy and offers information to support restorers in conservation works. Full article

Biofouling is the accumulation of marine organisms on submerged surfaces and has negatively impacted several industries while aiding in the spread of invasive species. Traditional antifouling paints, such as tributyltin and copper-based paints, have proven toxic to marine environments, necessitating the use of novel, less toxic alternatives. Previous research has shown that antifouling paints made from essential oil-rich superfruits and medicinal herbs have been effective in preventing precipitation accumulation, including bacterial and mineral accumulation. This study examined the antifouling potential of spirulina and fucus, two algae rich in antioxidants and essential oils. Extracts were analyzed for antioxidant and essential oil content before being subjected to a three-week-long antifouling test. A post-test surface analysis was then performed, and the precipitation count per mm of slide was calculated, followed by a comparison with previous extracts from superfruits and medicinal herbs. After testing, fucus has a minimum bacterial count of 41.4 ± 2.0 per mm in freshwater and 14.0 ± 0.7 per mm in saltwater. Spirulina had a minimum precipitation count of 13.9 ± 2.8 per mm for freshwater and 6.6 ± 1.3 per mm for saltwater. As such, spirulina performed better than fucus, superfruits, and medicinal herbs in both saltwater and freshwater, except for when compared to results from ginger extracts in saltwater. Full article

Titanium compounds are an integral component for paint pigments, food additives (E171), catalysts, precursors for resistant structural materials, medicine, and water, and air purification and disinfection processes. A new and rather promising trend for titanium dioxide production is obtaining it from minerals with magnesium titanium structure. Magnesium titanates obtained by pyrometallurgical processing of quartz–leucoxene concentrate (oil sandstones). It was found that the optimal pyrometallurgical processing conditions were 4 h and a temperature of 1425–1450 °C, with TiO₂ → Mg_XTi_YO_Z conversion exceeding 95%, and that sulfation of the magnesium titanate mixture with 60–70% H₂SO₄ for 150–210 min allows a 95% extraction of titanium compounds into solution. Investigation of the mechanism of titanium compound precipitation from Mg-Ti-containing sulfuric acid solutions revealed that in the pH range from 3 to 6, only titanium compounds were extracted from solution, while coprecipitation of magnesium compounds begins only at pH above 6.5. The product obtained by precipitation is titanium dioxide with an anatase structure, with particle distribution ranging from 0.8 to 5.0 µm and a developed surface area over 250 m²/g with mesopores characteristic of sorption materials. Full article

LACMA’s 19th-century Tibetan Altar Table with Auspicious Symbols is characterized by a complex stratigraphy comprising animal glue-based ground and paint layers, a presumably original tung oil-based varnish, and a dark surface layer composed of a complex mixture of paraffinic wax, shellac, and rapeseed oil, which obscures the object’s original decorative scheme. This study examines the use of nanostructured fluids and organic solvents confined within hydrogels and organogels for the selective removal of the dark surface layer while preserving the underlying paint and varnish. Following the analysis of the artwork’s constituent materials, cleaning tests were conducted and evaluated using visible and ultraviolet fluorescence (UVF) imaging, spectrophotometry, and digital microscopy. The homogeneous absorption of solvent mixtures by the organogels was assessed through gas chromatography–mass spectrometry (GC–MS). Results indicate that confining cleaning fluids within the gels’ porous networks significantly improved solvent retention and control of fluid release. While conventional cleaning methods proved insufficiently selective, the gradual release of a nanostructured fluid containing a small amount of benzyl alcohol, combined with the nanostructural properties of the poly(vinyl alcohol)–sebacic acid (PSA2) hydrogel, enabled targeted removal of the surface layer while preserving the integrity of the underlying layers. Full article