Search Results (45)

Dyed wool samples and lake pigments prepared from the same dyestuffs were exposed to light over the course of 14 months. Brazilwood or sappanwood, cochineal, madder, and weld were used for both wools and pigments, with the addition of dyer’s broom, indigo, and tannin-containing black dyes for the wools and eosin for the pigments. The wools were dyed within the MODHT European project on historic tapestries (2002–2005), using recipes derived from fifteenth- to seventeenth-century sources. The pigments were prepared according to European recipes of the same period, or using late nineteenth-century French or English recipes. Colour measurements made throughout the experiment allowed for overall colour difference (ΔE₀₀) to be tracked and half-lives to be calculated for some of the colour changes. Alterations in the samples’ hue and chroma were also monitored, and spectral information was collected. The results showed that, for both textiles and pigments, madder is the most stable red dye, followed by cochineal, and then brazilwood. Eosin was the most fugitive sample examined. Comparisons of textile and lake samples derived from the same dyestuff, whether red or yellow, indicate that the colourants are more stable when used as textile dyes than in analogous lake pigments. Full article

Rapeseed (Brassica napus L.) has been cultivated as an ornamental plant in recent years. However, the metabolic and regulatory processes involved in pigment accumulation in. B. napus flowers are poorly understood. To address this knowledge gap, we conducted a multi-omics analysis of the orange-red-flowered ‘OrP’ and the yellow-flowered ‘ZS11’ rapeseed cultivars. The total anthocyanin content of ‘OrP’ petals was 5.420-fold and 3.345-fold higher than ‘ZS11’ petals at the S2 and S4 developmental stages, respectively. The red coloration of ‘OrP’ flowers resulted primarily from the presence of anthocyanin pigment derivatives. The up-regulated differentially expressed genes (DEGs) of four stages in ‘OrP’ were found to be significantly enriched in phenylpropanoid, flavonoid, and anthocyanin metabolism-associated GO and KEGG terms. Weighted Gene Co-expression Network Analysis (WGCNA) revealed that 51 DEGs were linked to anthocyanin metabolism, including several structural genes such as BnaCHS, BnaF3H, BnaF3′H, BnaCHS, BnaDFR, BnaANS, BnaUGTs, and the transcription factor (TF) genes BnaHY5, BnaBBX22, BnaPIL1, BnaPAP2, BnaTT8, BnaTTG2, and BnaMYBL2. Furthermore, we found that three main factors affecting the relative content of anthocyanins in petals were likely responsible for the fading of ‘OrP’ petals, namely the significantly down-regulated expression of genes (BnaDFR, BnaANS, BnaPAP2, BnaTT8, and BnaTTG2) related to anthocyanin biosynthesis, the significantly up-regulated expression of genes (Bna.BGLUs, Bna.PRXs, and BnaMYBL2) related to anthocyanin degradation or the negative regulation of anthocyanin biosynthesis, and the rapidly increasing petals area. Full article

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

The emulsification of natural pigment is a widely utilized strategy to enhance its stability in the food industry. However, high turbidity in emulsions often causes color fading, limiting their application. Here, we developed a comprehensive Pickering emulsion (PE) system to improve the color intensity and stability of turmeric oleoresin (Tur) under various food processing conditions. Specifically, the effects of two encapsulation positions within the PE were compared: the inner oil phase (Tur-IPE) and the outer solid particle layer (Tur-OPE). Lysozyme and carboxymethyl cellulose nanoparticles (NPs) were used as natural solid particle surfactants, with their successful formation confirmed through physical property analysis and FTIR spectroscopy. The optimal oil fraction (φ) for suitable physical properties of PE was determined to be 0.2. Interestingly, Tur-OPE significantly exceeded Tur-conventional emulsions (Tur-CE) and Tur-IPE in terms of color vividness, exhibiting higher redness and lower lightness (p < 0.05). During thermal processing at 70 and 90 °C, all emulsions demonstrated significantly enhanced heat resistance, retaining 1.3 to 1.6 times more Tur, respectively, compared to unencapsulated Tur (free Tur) (p < 0.05). Furthermore, Tur’s pH instability was significantly overcome by encapsulation in all emulsion systems (p < 0.05). During 4 weeks of storage period, Tur-OPE demonstrated the highest retention rates, with the half-life of Tur increasing in the following order: free Tur < Tur-CE < Tur-IPE < Tur-OPE. Thus, we highlighted the important role of encapsulation position in PEs in improving and maintaining the color stability and vividness of natural pigments under various food processing conditions. Full article

Indigo leaves from various plant species are sources of dyes/pigments, not fully exploited for making sustainable textiles. Blue indigo vat dye extracted from indigo leaves yields high wash color fastness but fades slowly with light, and is not easily used for direct printing. Indigo leaves can be used to produce textiles of various color shades, while light-resistant Mayan-inspired hybrid pigments have not yet been used for textile coloring. Using blue indigo dyes from three plant species, with exhaustion dyeing, intense wash-resistant blue-colored textiles are produced, and in the case of Indigofera Persicaria tinctoria, textiles have antibacterial activity against S. epidermis and E. coli. A 100% natural Mayan-inspired blue indigo pigment, made from sepiolite clay and natural indigo dye, was used both in powdered and paste forms to perform pigment textile dyeing by pad cure process, and direct screen printing on textiles. A water-based bio-binder was used efficiently for both padding and printing. Bio-based Na Alginate thickener allowed to produce prints with good color-fastness on both polyester and cotton fabrics, while bio-based glycerin produced excellent print color fastness on polyester only: wash fastness (5/5), dry and wet rub fastness (5/5) and light fastness (7/8). Full article

The wood of Scots pine (Pinus sylvestris), silver birch (Betula pendula), and European aspen (Populus tremula) was thermally modified in nitrogen under pressure. Three commercial linseed oil-based coatings without or with brown and grey pigments were applied to the specimens. Specimens were placed outside, and weathering stability was assessed for 3 months. The test measured total surface colour change (ΔE) and colonization by wood dicolouring fungi. Following the test, all uncoated specimens demonstrated poor colour fastness and resistance to fungal growth. All tested coatings were unsuitable for protecting untreated wood from dicolouring fungi. The transparent coating was inefficient since it did not significantly prevent untreated or TM wood from fading, and fungal resistance was increased only for a few TM regimes. The colour fastness of specimens with pigmented coatings was enhanced. Specimens with a grey coating exhibited the lowest ΔE and remained consistent throughout the test period. TM specimens with coloured surfaces exhibited greater fungal resistance. However, not all TM aspen and birch regimes had a sufficient growth mark (rating 0 or 1). TM aspen was less resistant to fungi, whereas TM pine displayed very strong fungal resistance across all TM regimes. Full article

The pigments of cultural color paintings have faded with the passage of time. Color segmentations are essential for digital color reconstruction, but the complexity of color paintings makes it challenging to achieve high-precision segmentation using previous methods. To address the challenges of color painting segmentation, an optimized strategy based on U-Net is proposed in this paper. The residual blocks of a residual network (ResNet) are added to the original U-Net architecture, and a UR-Net is constructed for the semantic segmentation of color paintings. The following steps are taken. First, datasets of color paintings are obtained as training and test samples and are labeled with the two following pixel colors: earth red and ultramarine blue. Second, residual blocks are improved and added to fit the U-Net architecture. Then, a UR-Net is constructed and trained using the samples to obtain the semantic segmentation model. Finally, the effectiveness of the trained UR-Net model for segmenting the test samples is evaluated, and it is compared with the K-means clustering algorithm, ResNet, and U-Net. Data from several studies suggest that the segmentation accuracy of the UR-Net model is higher than that of other methods for the color segmentation of painted images, and the IoUs of the segmented earth red and ultramarine blue pixels are 0.9346 and 0.9259, respectively, achieving the desired results. The proposed UR-Net model provides theoretical and methodological support for further in-depth research on color recognition and segmentation of cultural color paintings. Full article

Cultural heritage digitization is of great significance for the protection, restoration, and rejuvenation of cultural relics. In particular, the investigation of fading mechanisms is essential for virtual restoration to accurately recreate the original appearance of artifacts and facilitate humanistic and historical research. For the purpose of investigating the color fading mechanism of pigments, we propose a color fading time series model using a combined long short-term memory recurrent neural network modified by the gray wolf optimization algorithm (GWOAD-LSTM). First, the general gray wolf algorithm was scaled up to two dimensions and combined with an LSTM model for optimal parameter search. Second, six pigments commonly used in painted artifacts were subjected to simulated aging experiments. Third, by applying the experimental data to different predictors, the results of the Back Propagation Neural Network (BPNN), Long Short-Term Memory (LSTM), Long Short-Term Memory on Gray Wolf Optimizer (GWO-LSTM), and GWOAD-LSTM models were compared. The results showed that our proposed GWOAD-LSTM model outperformed other models in terms of accuracy and generalization ability, especially in predicting hLC color attributes. Our study aimed to provide a new application tool for the restoration and rejuvenation of painted artifacts. Full article

Caisson paintings are an integral part of the unique interior decoration ceiling of traditional Chinese architecture. There are a large number of Yuan Dynasty caisson paintings in the Puzhao Temple, in Hancheng, Shaanxi Province, China. These caisson paintings have exquisite patterns and rich colors, which are rare artistic treasures of the Yuan Dynasty. In the history of nearly 700 years, due to various environmental and human factors, the caisson paintings have experienced various degradation; for example, the paper of the caisson paintings is acidified, the surface is polluted, the color is faded, mottled, and it is difficult to identify. Therefore, their protection is vital. In order to ensure the scientific and targeted development of the protection scheme, this study conducted a comprehensive and in-depth analysis of the paper fibers, pigments, adhesives, wood supports, and pollutants of the caisson paintings and carried out a series of protection experiments in the field and laboratory, providing a step-by-step review of the protection treatment application for the caisson paintings. Mechanical and wet cleaning were used to remove the pollutants. The caisson painting was deacidified with a barium hydroxide ethanol solution, and the paper and pigments of the caisson painting were strengthened with water-based fluorine. Several conservation problems, such as the removal of pollutants, the deacidification of acidified paper, and the reinforcement of flaking paper and pigments, were solved. Meanwhile, good conservation and restoration results for caisson paintings were obtained. This research method of combining theory and practice has greatly improved the scientificity and success rate of conservation work. These research results provide valuable experience and reference for other caisson paintings in similar environments. Full article

Colored asphalt pavements have been implemented in South Korea to enhance visibility and lane distinction; however, color fading, accelerated deterioration, and increased pothole occurrence have been noticed. As a solution, alternative materials that can be used for the construction of colored asphalt pavements are being explored. This study evaluates the feasibility of using mudstone aggregate in constructing colored asphalt pavement in South Korea. Initially, aggregate quality tests were conducted on mudstone samples to assess their suitability compared to standard criteria. To enhance the visibility and color retention of colored asphalt, addition of pigment in the colored asphalt pavement mixture was considered and evaluated. The asphalt mixtures were evaluated for deformation, crack and viscoelastic properties using the Kim test, indirect tensile (IDT) strength test, and dynamic modulus test, respectively. Results showed that mudstone aggregate exceeded quality standards and the colored asphalt mixtures demonstrated superior deformation strength and crack resistance compared to typical SMA. However, the addition of pigment slightly reduced these properties. Overall, the findings suggest mudstone aggregate as a viable alternative for constructing colored asphalt pavements, offering potential improvements in durability and color retention. Full article

A group of wall painting fragments discovered at Ulpia Traiana Sarmizegetusa, an important Roman archeological site located in the former Roman province of Dacia (Romania), have been investigated with the aim of defining the material composition of their pictorial layers and exploring the pictorial technology used. In order to preserve the integrity of the murals and minimize sampling, an array of non- and micro-invasive techniques has been employed, including X-ray fluorescence, laser-induced breakdown spectroscopy, Fourier transform infrared spectroscopy, and hyperspectral imaging. In accordance with previous studies, the identified color palette was mainly based on iron-rich earth pigments (red and yellow ochres, green earth) and carbon-based blacks (soot/charcoal, bone black). Egyptian blue, lazurite, some lead-based pigments, and potentially indigo were also identified (in complex mixtures) on the uppermost paint layers, typically applied a secco over the a fresco background. The presence of expensive pigments and the existence of a red preparatory drawing, documented for the first time in the region, indicate that the original wall paintings had elaborate schemes and, secondly, reflect the patron’s wealth and social status. Hyperspectral imaging was able to retrieve some faded paint layers in certain cases, helping to recover lost decorative details, an indicator of a more complex polychromy compared to what we see today. The obtained results add important contributions to the limited corpus of data regarding the technical know-how of decorative polychrome painting on plaster found in Roman archeological sites in Romania. Full article

Permanent makeup (PMU) is a popular form of tattooing applied to the eyebrows, eyelids, and lips for corrective and aesthetic purposes. It also has medical applications, such as reconstructing the breast areola, mimicking hair follicles on the head, and covering scars and vitiligo. Unlike body tattoos, PMU often requires reapplication to maintain color density and shape, as the pigments fade over time. This fading is likely due to the characteristics of PMU colorants rather than the application methods or apparatuses. The aim of our study was to assess the application depth of PMU colorants and tattoo ink after procedures. PMU colorants typically contain larger pigment particles in their composition compared to the nanoparticles found in traditional tattoo inks. We applied both tattoo ink and PMU colorants on SKH-1 mice using a PMU apparatus and a tattoo apparatus. To clarify the semi-permanent nature of PMU compared to the more permanent body tattoos, skin biopsies were performed at various intervals throughout this study. The results showed that PMU and tattoo ink were placed at approximately the same depth but exhibited key differences in behavior. PMU with larger inorganic pigments fades over time, while tattoos with smaller, stable organic pigments ensure permanence. Full article

As a representative genetic and economic trait, pigmentation has a strong impact on speciation and adaptation. However, information and reports on microRNAs (miRNAs) associated with pigmentation remain limited. The Midas cichlid fish, with three typical distinct stages of body color pattern, “black-gray-gold”, is an ideal model system for investigating pigmentation traits. In this study, miRNA libraries from scale tissues with the attached epidermis of Midas cichlids at three distinct stages of color transformation, black (B), transition (T), and gold (G), were sequenced using Illumina sequencing technology. In total, 53 (B vs. G), 88 (B vs. T), and 57 (T vs. G) miRNAs were differentially expressed between the respective groups. Target genes of the identified miRNAs were predicted, and the results showed that multiple target genes were related to pigmentation and pigment–cell differentiation. The miRNA–mRNA regulatory network suggests that miR-183-x and miR-133-x were predicted to be involved in regulating morphological color changes in Midas cichlids. The results advance our understanding of potential functions of miRNAs in skin pigment differentiation and early skin color fading of fishes. Full article

Long-term aging has traditionally been associated with issues such as color fading and oxidation; therefore, it limits grape wine production. Here, we analyzed 90 bottles of mulberry wine aged for various periods (up to 12 years) and observed unique trends in color, flavor, and aroma compounds during prolonged aging. Results from Somers and methylcellulose precipitation (MCP) assays indicated that the tannin and anthocyanin concentrations in newly fermented mulberry wines were 167 to 216 mg/L and 1.04 to 1.37 g/L, respectively. The total phenolics, tannins, and anthocyanin contents exhibited significant negative correlations with aging years, while the non-bleachable pigment content and hue showed positive correlations with aging times. High-performance liquid chromatography–electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) analysis further revealed a positive correlation between the content of pyranoanthocyanins (including cyanidin-3-O-glucoside-pyruvic acid, cyanidin-3-O-glucoside-acetaldehyde, cyanidin-3-O-glucoside-4-vinocatechol, and cyanidin-3-O-glucoside-4-vinophenol) and aging times, whereas the impacts of aging on the polymeric pigment (cyanidin-3-O-glucoside-epicatechin) were not observed. This suggests that the anthocyanins in mulberry wine primarily transformed into pyranoanthocyanins rather than polymeric pigments during aging. The aging-induced reductions in protein, polysaccharide, and key aroma compounds (contributing to the fruity, sweet and floral odors) remained unaffected by prolonged aging. Full article

Structural hydroxide groups in layered magnesium–aluminum double hydroxides were partially replaced by fluoride ions. Fluorinated and fluorine-free materials were used as hosts for two dyes, carminic acid and hydroxyl naphthol blue, resulting in a hybrid pigment color palette. The pigments were produced by two ways, either incorporating chromophore during the synthesis of the layered double hydroxide or in a post-synthesis step through the memory effect of the LDHs. Additionally, the pigments were protected with a magnesium hydroxide phase to prevent the color from fading over time. The pigments were stable for periods as long as 10 years. The color properties of the pigments were significantly influenced by the host of dye since the presence of fluorine directly influences the acid–base properties of the layered double hydroxides. The pigments conferred their color to white cream in the preparation of colored creams. The colored creams acquired the color of the layered pigment. Full article