Search Results (36)

The artisanal production of paints using inorganic pigments from the Cusco Valley is considered a sustainable alternative to the use of synthetic industrial paints. This approach not only helps reduce the environmental footprint associated with the use of volatile organic compounds (VOCs) but also utilizes local materials. The present study evaluates the physical and mechanical properties of paints obtained from natural pigments through standardized tests based on the American ASTM standards, focusing on adhesion (ASTM D-3359), drying time (ASTM D-1640), surface hardness (ASTM D-3363), and the performance of the paints when exposed to the environmental factors of Cusco (under real conditions). In this regard, the pigments were extracted from traditional quarries and processed through the sedimentation method (MS) and ball milling (MG). The produced paints were formulated with the addition of polyvinyl acetate (PVA) as a binder and water as a solvent and were applied to standardized panels. The results show that all samples meet the requirements of the technical parameters, demonstrating good adhesion, appropriate drying times, and acceptable hardness for architectural coatings, Chromatic variations (ΔE*) were recorded depending on the processing method and the level of environmental exposure, with paints containing ground pigments (MG) being more resistant to fading. This study concludes that these artisanal formulations represent a technically viable and culturally relevant alternative to industrial coatings, especially in contexts of heritage restoration or sustainable architecture. Full article

This paper presents numerical studies of the viscous droplet impact on dry and wetted solid walls for spray painting applications, focusing on air entrapment, film structure, and flake (flat pigment) orientation. The results were compared with experimental observations using various high-speed camera arrangements. For paint droplet impact on dry substrates, a dynamic contact angle model was developed and used in numerical simulations. This contact angle model was verified with experimental observations. For the droplet impact on wet surfaces, characteristic crater sizes (diameter and depth) were defined considering also the effect of the film thickness. A strong correlation with the droplet impact Reynolds number was observed. In addition, a user-defined 6DOF (6-degrees-of-freedom) solver was implemented in a CFD program to perform calculations of rigid body motions within the impacting droplet, technically relevant for the resulting effect of flakes in metallic effect paints. The developed models were applied in parameter studies to further clarify the existing dependencies on application and fluid parameters more quantitatively. The simulation results are helpful to understand and to improve painting processes with respect to the final quality parameters. Full article

This study focuses on investigating the stability of modern and contemporary paints based on manganese violet pigment PV16 (NH₄MnP₂O₇) when exposed to atmospheric pollutants, specifically sulfur dioxide (SO₂) in the presence of high relative humidity. In particular, this study aims to investigate the role of PV16 in increasing the degradation processes of various modern binders. Therefore, the objectives of this research can be divided into (i) evaluating the chemical modifications involving PV16, (ii) investigating the degradation processes that occur in different organic matrices (i.e., drying oil, alkyd resin, and acrylic and styrene–acrylic emulsions), and (iii) comparing the chemical stability of model and commercial paints. The paints were analyzed by 3D Optical Microscopy, Attenuated total Reflection–Fourier-Transform Infrared spectroscopy (ATR-FTIR) and μ-Raman Spectroscopy, Scanning Electron Microscope coupled with Energy Dispersive X-Ray spectroscopy (SEM-EDX), X-Ray Powder Diffraction (XRPD), Fiber Optic Reflectance Spectroscopy (FORS), Pyrolysis–Gas Chromatography–Mass Spectrometry (Py-GC/MS), and Thermally assisted Hydrolysis and Methylation (THM) of Py-GC/MS (THM-Py-GC/MS). The results show that when exposed to high relative humidity and SO₂, PV16 presents a colorimetric change from violet to grey; several compounds crystallize on the surface; and, depending on the binder, various degradation reactions occur. This study highlights the susceptibility of manganese violet pigment PV16 under certain environmental conditions, which may be considered to define adequate conservation strategies for works of art containing this specific pigment. Additionally, the results obtained within this investigation point out the need to expand the chemical knowledge of this material for engineering, sensing, and industrial applications. Full article

Building and finishing materials are among the main sources of indoor air pollution and can provide ideal substrates for microbial growth. Environmental factors can induce physico-chemical aging of these materials, altering their composition and increasing their vulnerability to microbial growth. To mitigate this risk, manufacturers are increasingly adding biocidal agents to these materials to prevent microbial contamination. The aim of this project was to study the sensitivity of two different acrylic paints to fungal growth, before and after an aging process, and to assess the impact of aging on the effectiveness of the biocides contained in these materials. To do this, two paints (antifungal and normal paint) were applied to a wall covering (polyester-cellulose) before being subjected to accelerated aging. The later process was based on the addition of detergent or water and exposing the material to a visible light spectrum, moderate temperature (38 ± 6 °C), and ambient relative humidity (25 ± 17%). Prior to 30 days of incubation, the aged and unaged (“native”) materials were inoculated with fungal spores using a dry aerosolization system. Fungi behavior was then evaluated by the culture method. The results showed that the native and water-aged normal acrylic paint supported fungal growth at 95 ± 5% relative humidity. However, the use of the cleaning product during the aging process provided additional resistance of the materials against fungal growth. On the other hand, the antifungal paint showed no visible growth due to its biocide content. The accelerated aging and incubation processes led to the depletion of the biocides and thus a decrease in their effectiveness against mold development. Full article

The need for ending plastic waste and creating a circular economy has prompted significant interest in developing a new family of composite materials through recycling and recovery of waste resources (including bio-sourced materials). In this work, a family of natural fiber-reinforced plastic composites has been developed from paint pail waste recycled polypropylene (rPP) and waste wool fibers of different diameter and aspect ratio. Composites were fabricated by melt processing using polypropylene-graft-maleic anhydride as a compatibilizer. The internal morphology, interfacial and thermal characteristics, viscoelastic behavior, water sorption/wettability, and mechanical properties of composites were studied using electron microscopy, high-resolution synchrotron Fourier transform infrared microspectroscopy, thermal analysis, rheology, immersion test, contact angle measurement, tensile test and flexural test. The composite matrix exhibited an internal morphology of coalescent micro-droplets due to the presence of polyethylene and dry paint in the rPP phase. In general, the rheological and mechanical properties of the composites comprising higher-aspect-ratio (lower diameter) fibers exhibited relatively superior performance. About an 18% increase in tensile strength and a 39% increase in flexural strength were measured for composites with an optimal fiber loading of 10 wt.%. Interfacial debonding and fiber pull-out were observed as the main failure mechanism of the composites. The developed composites have potential for applications in automotive, decking, and building industries. Full article

This work explores a new application of titanium nitride nanoparticles (TiN NPs) as efficient photothermal materials in enhancing the greenhouse effect. We demonstrate that a simple greenhouse using TiN NPs-embedded black paint boasts several advantages in solar drying technology, which are indicated by the drying of red chilli. In particular, the greenhouse using TiN NPs significantly improves the drying efficiency, which reduces the mass of red chilli by approximately four times and results in dried chilli with a moisture content of 10% within two days. In addition, by conducting long experiments in various environments, we found that the relative humidity can have a predominant role over the temperature in the solar drying of red chilli and observed that the re-adsorption of moisture can take place during the drying process, which prolongs the drying time and reduces the quality of the dried products. Full article

Traditional wood protection methods involving fire retardants and preservative paints have limitations, requiring periodic renewal during a building’s lifecycle and generating hazardous waste post-use. This study aims to achieve a multifaceted solution, simultaneously enhancing wood’s resistance to fire, fungi, and insects using natural and/or recycled mineral waste components containing lime that react with pozzolanic additives. Additionally, organic humates provide protection against pests (fungi and insects). Following the crystallization processes within the wood’s structure, it exhibits increased resistance to fire, as demonstrated by tests involving seven species. The study also describes wood tolerance tests against termites (Reticulitermes flavipes) that yielded promising results, indicating that the treated wood is an unsuitable habitat for these pests. An additional advantage for the timber industry is that the crystallized composite filling the wood’s pores minimizes wood stitching and reduces internal stresses during the drying process. This property enhances the utility of timber in frame structures and carpentry joints, which are less susceptible to moisture-induced movements. The timber impregnated by our method can also be repurposed or disposed of as non-hazardous waste. This research thus offers an eco-friendly and effective approach to wood protection. Full article

This paper investigates the oil on canvas painting Boat scene (1974) by Liu Kang (1911–2004), belonging to the National Gallery Singapore (NGS). The focus is on disfiguring paint protrusions in a specific area and colour in the composition. Moreover, in search of the possible factors responsible for the creation of the protrusions, the structure and composition of the paint layers were determined. Three possible reasons were put forward to explain this phenomenon: deliberate textural effects, the expansion of metal soaps and unintentional paint contamination during the artistic process. Investigative techniques such as technical photography, digital microscopy, optical microscopy (OM), polarised light microscopy (PLM), field emission scanning electron microscope (FE-SEM-EDS) and attenuated total reflectance micro-Fourier transform infrared spectroscopy (ATR μ-FTIR) were employed to analyse paint layers, including protrusion samples. The analyses revealed that the protrusions resulted from an unintentional contamination of the oil paint during the artistic process by dry fragments of different pigment mixtures bound in drying oil. Zinc soaps were found in significant concentrations within the protrusions and other parts of the painted scene. Nevertheless, the metal soaps do not pose a direct risk to the integrity of the paint layers at the time of this research. The analyses highlight the potential challenges caused by the protrusions that conservators may face while caring for the painting. The research contributes to our ongoing comprehension of the artist’s working process. Full article

In order to control the production cost of lacquer products, Cu–ethanolamine nanozymes were synthesized to simulate laccase to catalyze the oxidation and polymerization of urushiol. First-principles calculation results indicate that the D-band center of Cu center in the nanozymes was closer to the Fermi level than that of laccase, so Cu–ethanolamine was more conducive to the adsorption of substrate. The activation energy of Cu-ethanolamine catalyzed the oxidation of urushiol was significantly lower than that of laccase. Therefore, we inferred that the synthesized Cu–ethanolamine had a better catalytic effect on urushiol and was more conducive to paint film drying. By comprehensive comparison, the drying characteristics of the Cu–ethanolamine and raw lacquer with a 1:20 ratio are found to be closest to those of the raw lacquer, and the drying time is significantly shortened. The reaction results of the drying process performance test on the sample indicate that the composite lacquer can achieve the market-desired effect and performance requirements of the paint process. Full article

In the ancient Chinese recipe for composite mortar used in the construction of ground layers for architectural painting, the mixture of porcine blood and lime water is one of the constituent materials. Herein, according to the traditional recipe, the interaction between porcine blood and lime water was systematically and deeply investigated. The experimental investigation demonstrated that porcine blood mixed with lime water at the ratio found in the recipe can form a hydrogel with a hydrophobic surface. During air-drying, the lime water in porcine blood hydrogel can react with CO2 to form calcium carbonate. The crystal morphology of the formed calcium carbonate depends on the surrounding micro-environment of calcium ions in the porcine blood hydrogel. The formed morphology of calcium carbonate includes small calcite crystallites, small graininess calcite crystals with round features, calcite aggregates with layered ladder-like structures, and amorphous calcium carbonate (ACC). Interestingly, the calcium carbonate formed in the inner part of the porcine blood hydrogel exhibits lamellar distribution due to a Liesegang pattern formation. Based on the findings that the porcine blood hydrogel has surface hydrophobicity and brittleness, it can be predicted that in the preparation process of composite mortar for ancient building color painting base course, porcine blood used in the form of a hydrogel is not only easier to be dispersed in hydrophobic tung oil than in liquid porcine blood but also the affinity between porcine blood gel and tung oil is enhanced. As constituent material dispersed in the composite mortar, the layered distribution of calcium carbonate in the porcine blood hydrogel may presumably be beneficial to reduce the internal stress of the composite mortar material. Full article

Affected by the improper operation of the workers, environmental changes during drying and curing or the quality of the paint itself, diverse defects are produced during the process of ship painting. The traditional defect recognition method relies on expert knowledge or experience to detect defects, which is not conducive to ensuring the effectiveness of defect recognition. Therefore, this paper proposes an image generation and recognition model which is suitable for small samples. Based on a deep convolutional neural network (DCNN), the model combines a conditional variational autoencoder (DCCVAE) and auxiliary conditional Wasserstein GAN with gradient penalty (ACWGAN-GP) to gradually expand and generate various coating defect images for solving the overfitting problem due to unbalanced data. The DCNN model is trained based on newly generated image data and original image data so as to build a coating defect image classification model suitable for small samples, which is conducive to improving classification performance. The experimental results showed that our proposed model can achieve up to 92.54% accuracy, an F-score of 88.33%, and a G mean value of 91.93%. Compared with traditional data enhancement methods and classification algorithms, our proposed model can identify various defects in the ship painting process more accurately and consistently, which can provide effective theoretical and technical support for ship painting defect detection and has significant engineering research value and application prospects. Full article

This paper presents research on the degradation processes of the fresco painting in the cave church of Corbii de Piatră Hermitage under the influence of meteoric infiltration water and environmental factors. The medieval fresco dates from the end of the 13th century and the beginning of the 14th century, being painted on a sandstone wall. The infiltration of meteoric water through this wall, the temperature variations, the environment and the repeated wetting/drying processes determined the degradation of the fresco, resulting in its detachment from large surfaces. This research established correlations between the processes that take place, the structural transformations, the changes in composition and the adhesion of the fresco to the sandstone wall. The results have been made available to conservation and restoration specialists, in order to choose appropriate materials and technologies. This paper presents findings regarding the pictorial material and introduces new analysis techniques in research on the degradation processes of the fresco painting in the cave church of Corbii de Piatră Hermitage under the influence of meteoric infiltration water and environmental factors. Full article

This article presents results on the use of a new material as a solidifying agent and/or color-fixing agent. A special polysaccharide material extracted from the prickly pear cactus (Opuntia ficus indica) was tested on historical materials and modern papers. An old book from the 18th century was chosen as historical material. From the mentioned book 42 pages were taken, on which a conservation and restoration pretreatment was performed before applying the polysaccharide material: sampling, fiber analysis, dry cleaning, ink solubility, pH test, thickness measurement and wet cleaning. The paper sheets provided for the test were divided into 4 groups, 3 of which were treated with gel and one left untreated as a reference. The division into groups is not only due to the different method of application, but also due to the process of gel extraction. The effect of the treatment was analyzed using FTIR-ATR. To test the mucilage as color-fixing agent 2 samples were prepared using watercolor papers colored with 6 different watercolors applied to 2.5 cm² samples for each color in two rows of different intensity. One of the 2 samples was treated with gel, but both were immersed for 3 times in a water-ethanol solution for approximately 20 min as is standard practice in conservation and restoration. After washing, both specimens were subjected to colorimetric analysis to assess their differences. The results provided satisfactory evidence for the protection of paints sensitive to aqueous treatments and suggest the use of mucilage as a new material in cleaning method for water-soluble media. Full article

The economic viability of guayule as an industrial crop for natural rubber production depends largely on the potential valorization of these co-products. According to the studies carried out on the subject, there is a broad consensus on the added value of the resin and bagasse in different fields of application. The process of extracting natural rubber from guayule produces mainly bagasse (±80% of the total dry mass) and resin (±10% of the total dry mass). According to guayule research, high-value co-products significantly improve the economic viability of guayule as an industrial crop and offset a substantial portion of the cultivation and processing costs. According to studies, resin remains the most fluctuating value; reducing this uncertainty, through future research on resin applications, it is essential to the success of guayule as a natural rubber raw material. It finds applications in different industrial fields, such as coatings, varnishes, paints, treated wood, biocontrol agents and controlled-release formulations. Bagasse is composed primarily of cellulose, hemicellulose, lignin and resin, and has a high calorific value, making bagasse a suitable fuel for on-site combustion to produce electricity and thermal energy. Bagasse combustion in this scenario is less complex than the logistics of biofuel production. Resin-containing guayule bagasse has been combined with a plastic binder to make high-density composite panels resistant to termite degradation. In addition, the resinous material can be solvent-extracted and used to impregnate wood with raw resin extract so that the wood is protected from destructive organisms. Guayule bagasse containing resin can modify the soil nature and improve the growth of vegetables compared to de-resinated bagasse. Full article

The fringe projection (FP) method is an outstanding tool for reconstructing painted surfaces. This technique, which has been used for conservation and digitization, does not damage the artwork and can reach sub-millimeter accuracy. To carry out this type of analysis, it is necessary to achieve the most accurate measurements possible. Measuring the precision that a projector-camera-object arrangement can achieve is a complex task. In this paper, we show an experimental method used to measure the accuracy of this technique with instrumentation within the reach of most conservation laboratories. The method consists of capturing, as a reference model, a stepped cylindrical Nylamid^® pyramid, as a construction whose shape, size, and manufacturing accuracy are known with high precision. The pyramid has eight well-defined steps, which are fashioned with an accuracy more exact than that of the fringe projection method. The height of each step was measured, obtaining the mean and variance of the height measurements fitted to a Gaussian distribution. In this work, we show the measured heights of the steps, obtained by varying the period of the fringes. The smallest detectable step height was less than 44.1 µm; however, this was obtained with a variance in the order of the step height. The smallest detectable step height with a small variance was 0.1008 mm. In addition to this accuracy measurement, a qualitative evaluation of a painting was carried out, finding the presence of possible superimposed thin layers, fabric, and microcracks, which commonly occur in the drying and aging processes. Further research would provide an experimental measurement of the method’s accuracy and its variance as essential for obtaining a confidence criterion that could then be applied to the model of the painting’s surface. Full article