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In this research we proposed and tested a solution for improving lightfastness of paperboard electrophotographic prints – enhancing the printed material with inks containing pearlescent pigments. The goal was to analyze how pearlescent pigments’ composition and the size of their particles affect lightfastness, and to assess whether this important property is influenced by the tone value of the initial ink layer. Therefore, lightfastness of the unprinted paperboard and the paperboard printed in electrophotography with medium and full coverage of black ink was measured before and after overprinting with pearlescent inks. The results indicate that pearlescent pigments can be efficiently used to prevent light induced degradation of both paperboard and the corresponding prints. The most significant improvements in lightfastness were noticed when pearlescent inks were printed directly onto the paperboard and on the prints with 50 % black coverage. The best protection from light was achieved with pigments containing only two layers – mica and ferric oxide. Pigments containing mica, titanium dioxide, and tin oxide provided satisfactory lightfastness of the printed paperboard even with the small surface coverage. No significant correlation was found between the size of pearlescent pigment particles and the lightfastness of the paperboard prints to which they are applied. [ABSTRACT FROM AUTHOR]

Microfade testing (MFT) was used to examine standardized wool samples dyed with 14 natural historic dyes, each prepared with five different mordants, to determine whether the lightfastness and colourimetric properties of these dyes vary as a function of the mordant. The addition of mordants changed the original colour of the dyes as well as potential patterns corresponding to ΔL*, Δa*, and Δb* such that the variation of lightfastness ranges from 0.25–0.70 units of Blue Wool Equivalence (BWE). Disregarding the effect of mordants, MFT showed that all dyes have lightfastness equivalent to BW3, indicating that they belong in the category of 'high sensitivity to light'. All dye-mordant combinations vary in lightfastness, such that even the least lightfast dye will have a mordant combination that is more lightfast than the most lightfast dye combined with a mordant that renders it less lightfast. The effect of mordants varies by dye: while one dye may demonstrate a difference in lightfastness of 0.56 units of BWE between the least and most lightfast mordant combination, another may show little or no difference (as low as 0.07 units of BWE). Overall, alum based mordants tend to produce the least lightfast combinations, followed by tin and iron, with copper and chromium producing the most lightfast combinations. This paper shows that there are no simplistic patterns of lightfastness between mordant-dye combinations with these 14 natural dyes. Identifying both dye and mordant is useful to better estimate the lightfastness of a dyed textile. [ABSTRACT FROM AUTHOR]

• Chemical structure of dyes is fundamental to the ageing and degradation process. • Ink-jet printing is an established method for producing contemporary works of art. • Glass protection also affects the print's resistance to light. • The choice of substrate is also crucial for the protection of prints. Ink-jet printing has recently been increasingly used for professional and domestic purposes. However, the degradation of ink-jet prints under the influence of external factors, predominantly light, can cause unexpected problems and lead to the limited life span of a product. It is therefore essential to have in-depth knowledge about the materials, i.e. paper and ink, used for ink-jet printing and to consider their lightfastness to assure the resistance of a print as a whole. The aim of the present research was to study the lightfastness of ink-jet prints protected with glass. Using a printer with dye-based inks, samples of cyan, magenta, yellow and black were printed on different paper substrates. Prints and substrates alone were exposed to the radiation of xenon light for a limited time to simulate the action of average daylight. Some of the samples were exposed to radiation without protection, while others were covered with ordinary window glass or glass which ensured UV protection. Afterwards, the changes on samples were evaluated spectrophotometrically and colour differences were calculated using the CIEDE2000 equation. The results showed that glass effectively reduces the photodegradation of ink-jet prints. Protection with UV glass proved to be more effective than with ordinary glass. The substrate selection was also significant in achieving print lightfastness, as much smaller colour differences were observed on the prints made on photo paper than on those printed on plain office paper. [ABSTRACT FROM AUTHOR]

A comparative analysis of the quality properties of coating materials based on linseed oil and alkyd film formers is provided in the paper. The advantages and disadvantages of linseed oil-based and alkyd-based coating materials are explored. Protective materials such as alkyd coating material for wood and drying linseed oil were applied on the compared pine-wood samples. The authors determined the drying time of linseed oil and alkyd coating materials on pine wood, the thickness of the dry film, heat resistance, lightfastness, as well as water resistance of protective and decorative coatings. Linseed oil-based coating materials form thin-layer coatings on the surface of wood, unlike coatings based on alkyd materials. Alkyd coating materials transitioned into a solid state faster than the linseed oil-based ones. Coatings based on linseed oil have a higher moisture resistance. Higher indicators of heat resistance were observed in coatings based on linseed oil materials. [ABSTRACT FROM AUTHOR]

Many studies have investigated light-induced damage to colourants in heritage collections using prepared samples of materials such as artist paints and dyed textiles. The body of research focuses primarily on the response of virgin materials, where colour change is assessed with respect to the original colour as light dose increases. From a practical perspective, most objects in museum collections have accumulated a significant light dose from illumination before acquisition, and subsequent years of exhibit lighting. When considering the risk of further degradation, it is often stated by heritage professionals that fugitive colourants with past light exposure are no longer as sensitive due to the slowing rate of visual damage. This is evident by studying 'fading curves', where the rate of colour change typically diminishes with increasing light dose. It remains unclear, however, to what degree the lightfastness of remaining colour changes with ongoing exposure. To address the issue, the light sensitivity of residual colour was investigated as a function of prior dose using a published dataset of colour measurements from textiles dyed with early synthetic colourants in the period of 1874–1905. The CIELAB colour values (D65/2°) for each material and dose increment were used to determine the future dose that causes a just-noticeable difference (JND), ΔE00 = 1.7, starting at different amounts of past exposure. This involved resetting the reference CIELAB values to that of the residual colour after each prior dose. The analysis provides an extension of our earlier work, where only the initial lightfastness was reported. A summary of the findings illustrates the shifting distribution of lightfastness, toward higher Blue Wool (BW) ratings with increasing exposure. As the dose progresses, dyes that start at BW1 sensitivity progress to BW2, then BW3 and so on. The findings from this work may assist with boundary approximations of object sensitivity when prior light exposure is known, or a reasonable estimate is available. An analysis of experimental data is summarised as a tool for this type of decision-making process. [ABSTRACT FROM AUTHOR]

Shear thickening fluids (STFs) are innovative materials that can find applications in smart body armor. However, the usage of STFs is limited by the aging of these materials. This work aims to analyze the influence of UV radiation on the aging process of STFs. The investigation was done experimentally, and artificial aging was applied to investigate the impact of UV radiation on the properties of STFs. The shear-thickening properties of obtained STFs were confirmed by viscosity measurements. The STFs based on PPG425, PPG2700, and KE-P10 exhibited a very high maximum viscosity of up to 580.7 Pa·s and 3313 Pa·s for the STF425 and STF2700, respectively. The aging of the obtained STFs caused the liquid matrix degradation, causing damage to the STFs and their change from liquid into solid. Furthermore, the FT-IR, 1H NMR, and 13C NMR spectroscopies were used for the confirmation of the breakdown of STFs. The FT-IR spectroscopy revealed the appearance of carbonyl groups in STFs after aging. Moreover, 1H NMR and 13C NMR spectroscopy confirmed the formation of the typical groups containing carbonyl groups. Our results demonstrate that STFs are UV light-sensitive and may lose their properties during storage. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to investigate the changes in the performance of ink formulations caused by the addition of compounds that improve the ink's physical properties to achieve an optimum formulation for inkjet printing, because of the importance and simplicity of this method. Design/methodology/approach: Ink samples were formulated using Acid Red 14 as ink colorant, different percentages of polymeric compounds including polyvinyl alcohol (PVA), polyvinylpyrrolidone and Carboxy methyl cellulose (CMC) as viscosity modifier compounds and surfactant as the surface tension enhancer. Formulated samples were adjusted in terms of fluid physical properties e.g. viscosity, density and surface tension, and the effect of used compounds on the improvement of both physical and colorimetric properties such as viscosity, surface tension, colorimetric coordinates and lightfastness has been evaluated to achieve the optimum printing inks to be printed on three different substrates. Findings: The experimental observations showed that CMC was the most compatible compound as the viscosity modifier as its viscosity value was in the printable range of 2–22 cP. Moreover, a flow-curve test was applied to the ink samples and their Newtonian behavior was approved. Based on the spectrophotometric test results of printed samples, the samples containing PVA provided acceptable lightfastness in comparison to other ink samples on every used substrate. Originality/value: An optimum relation between colorimetric coordinates of the printed samples and ink formulation could be considered and achieved. [ABSTRACT FROM AUTHOR]

From the invention of Perkin's Mauve in 1856, to publication of the first edition of the Colour Index in 1924, more than 1200 synthetic organic colourants were introduced. Some achieved commercial success, while others were rarely used for reasons such as high cost, low fastness, and toxicity. This turbulent period of innovation was largely driven by demand of the textile industry; however, synthetic colourants were subsequently adopted in many other applications. An understanding of the most common materials and their properties is therefore important to the study of heritage collections and their preservation. The risk of light damage during exhibition of objects is often a concern due to the fugitive nature of many synthetic colourants. To provide a foundation for focused research on synthetic dye identification and lightfastness, work was carried out to identify the most prominent of these colourants used in North America up to the year 1924 when the first edition of the Colour Index was published. Information was compiled and analysed from several sources including multiple editions of the Colour Index, and government documents related to the manufacture and trade of synthetic dyes that provide data from 1914 onwards. Cross-referencing between the information sources provided a summary of parameters for each colourant including the date of introduction, number of manufacturers, lightfastness, and quantity produced or imported in the United States. A document published in 1916 by the US Department of Commerce listed 259 colours with Schultz number imported during the 1913–1914 fiscal year, in quantities above 10,000 lb (4536 kg). Adding domestic products to the list, and removing duplicates, gave 289 individual colours with Schultz number imported and/or produced in the US. In addition, there were some imports of unknown composition: 96 azo, 23 sulphur, and 68 unclassified. Further review of census data from 1917 through the 1920's suggested that less than one quarter of the dyes listed in the Colour Index were imported or manufactured in significant amounts. The results of this analysis are presented as summary statistics, which are complemented by an open dataset publication to facilitate future research. [ABSTRACT FROM AUTHOR]

The lightfastness of prints is an important property for assessing their print stability. The objective of this study is to determine the lightfastness rate of printed films due to long‐time exposure by applying artificial neural network (ANN). Package printing is gradually becoming extremely important because its color and quality increase the marketability of the product. Sometimes it has been observed that the initial print quality is bright and attractive. However, with time, it degrades the exposure of light, water, or other external parameters. Thus, it reduces the marketability if its color degrades before its expiration. Therefore, the lightfastness of prints may be considered for the authenticity or validity of the product. The plastic film substrate is chosen because it has extensive usage in food and other packaging industries. The samples printed in the gravure process are exposed in artificial lightfastness tester BGD 865/A Bench Xenon Test Chamber (B‐SUN) for assessing the lightfastness of prints. The ocean optics spectroradiometer (DH2000BAL) is used to measure the spectrophotometric properties of prints before and after exposure. The obtained reflectance spectra are modeled by applying an ANN technique that is proposed to predict the fading rate of the printed film. The optimal model gives excellent prediction with the minimum mean square error for each color and a correlation coefficient of 0.80 to 0.99. ANN model and a Regression model (assuming first‐order kinetic equation) are compared for predicting the lightfastness properties of prints. The results show that the ANN has better prediction capability than the regression model. [ABSTRACT FROM AUTHOR]

Purpose: Stimulant-sensitive materials exhibit physical or chemical reversible changes in their properties as a result of environmental variables. One of these materials is thermochromic materials. Materials with thermochromic sensitivity change their color with heat exchange. For this reason, it can be used in many different fields such as security inks. Such substances decompose rapidly by being affected by weather conditions. Furthermore, the particle sizes are larger than normal pigments, and therefore, it is difficult to stabilize thermochromic dyes. Because of all these adverse conditions, thermochromic colorants must be protected before use in the ink. This protection is planned to be provided by the microcapsulation technique. The purpose of this study is to determine the thermochromic printing inks that can be stored stably by microcapsulation technique, to protect it from environmental conditions and the determination of printability parameters. Design/methodology/approach: In this study, capsules with a core material of thermochromic dyeing with polyurea formaldehyde (PUF) or poly-phenolmelamine formaldehyde (PMF) shell were synthesized at appropriate pH and temperature using the appropriate solvent and mixing speed. The chemical structure and dimensions of the obtained capsules were examined by ATR-FTIR and scanning electron microscopy, respectively. The produced thermochromic microcapsules were mixed with alkyd resin and mineral oil and screen printing ink was obtained. Printability tests such as surface morphology, color, gloss and light fastness were applied. Findings: As a result, it was determined that PMF is not a suitable encapsulation technique for thermochromic dyes under suitable conditions and eliminates thermochromic property by providing heat stability. It was found that PUF microcapsulation can be used in thermochromic dyestuff encapsulation and does not lose the thermochromic property. It has also been found that PUF microcapsules increase the lightfastness and stability of thermochromic dye ink. Originality/value: This study provides experimental research on the encapsulation of a thermochromic dye and its use in ink. [ABSTRACT FROM AUTHOR]

This study describes the lightfastness properties of printed foil samples due to long‐time exposure. Lightfastness is an important property for any kind of print products to assess their print stability. The fastness properties of prints can be described in terms of print durability and image stability. It may also be used for verification of printed expiry date and authenticity or validity of the product. Moreover, any kind of deterioration in package print quality will affect the product's sale adversely. Little work has been conducted to study the fastness properties of printed films and foils. In this work, blister foils printed in the gravure printing process have been taken as the sample as they have extensive usage in food and medicine packaging. An artificial lightfastness tester BGD 865/A Bench Xenon Test Chamber (B‐SUN) is used to study the light fastness of Cyan, Magenta, Yellow, and Black inks on the foil. The spectral curves and colorimetric values are measured using an Ocean Optics Spectroradiometer (DH2000BAL) before and after exposure. A kinetic model is proposed to predict the fading rate of the printed foil. The optimal model has given excellent prediction with a correlation coefficient of 0.90 to 0.93 for Cyan, Magenta, Yellow, and Black prints, respectively. The largest color difference ΔE00 is achieved for Yellow print followed by Magenta. Cyan and Black prints have shown small changes with time when the gravure prints are exposed to the artificial aging chamber. [ABSTRACT FROM AUTHOR]

Abstract The digitisation of an old inscription, lettering, calligraphy or handmade typography (i.e. metal or wood typeface) represents an important procedure for the permanence of cultural heritage. It can contribute to the national awareness, local economy or even add international recognition. The old typography from the 19th century used by the prominent Slovenian printer Jožef Blaznik was analysed. It was digitised with some optimisations for contemporary use. Moreover, its usability was tested, since this typeface had an important contribution to the use and preservation of the Slovenian language by means of advanced printing technology and high quality of the work. In order to study the differences among various typefaces, the digitised typeface was compared with the other two widely used in printed publications. The influence of type size, substrate and digital printing (NIP) technology on legibility and preserved information was compared by analysing chemical, physical and colorimetric properties of the paper and prints, along with the typographic properties and legibility testing, using standard methods and the unconventional non-invasive testing methods, e.g. image analysis. The results show that the digitisation of old typography from the 19th century was an appropriate method, and that it is necessary to consider the chosen typeface and its size to ensure information permanence and legibility of a text. The selected (Blaznic) typeface could be used in printed publications, still ensuring satisfied legibility. Furthermore, information permanence was satisfactory even when this typeface was used in small type sizes. Therefore, the Blaznic typeface could be recommended even today for the use in different graphic design solutions. [ABSTRACT FROM AUTHOR]

Purpose. The purpose of the work is to determine the dependence of the lightfastness of colours obtained on wool fabric with acid dyes on their chemical structure, namely, the chemical class, the structure of chromophore and the number of sulfo groups. Methodology. The study was carried out using seven acid dyes with a different structure of the chromophore and the number of sulfo groups in the molecule. All-wool fabric previously prepared by peroxide bleaching was subjected to dyeing. Dyeing of wool textile material was carried out in a method that was determined by the leveling power of each dye. The insolation of the dyed samples was carried out on a device with a mercury-tungsten lamp. The light fastness of the samples was evaluated according to BS 1006 UK/TN standard by determining color differences using a colorimeter. Findings. The article presents the results of a study of the effect of the structure of acid dyes on the lightfastness of the colours obtained. It is established the chemical structure of chromophore and the required number of sulfo groups in the acid dye molecule to provide light resistant colors on wool fabric. It has been proven that the number of sulfo groups is decisive for acid dyes from the point of view of chemical structure. It has also been established that azo dyes that have an oxy group at ortho-position to azo group form the light-resistant colours. Originality. The influence of the chemical structure of acid dye molecules — the chemical class of chromophore and the number of sulfo groups — on the lightfastness of the colours obtained on wool fabric has been studied. Practical value. The chemical structure of acid dyes, providing colours with high resistance to light exposure, was determined. [ABSTRACT FROM AUTHOR]

Purpose. The goal of the work is to determine the dependence of lightfastness of colours obtained by reactive dyes on the interlacing of cotton knitted fabrics. Methodology. The study was carried out using cotton knitted fabrics of various interlacing: plain, rib knitted fabric 1×1 and pique. Samples of knitted fabric were previously prepared by the combined method of washing and peroxide bleaching. Dyeing was carried out by reactive dyes brand Bezaktiv Cosmos periodically. The insolation of the dyed samples was carried out on a device with a mercury-tungsten lamp. The lightfastness of the samples was evaluated according to BS 1006 UK/TN standard by determining color differences at regular intervals using a colorimeter. Findings. The paper presents the results of a study of the effect of interlacing of cotton knitted fabric on the resistance of colours obtained by reactive dyes to light. It is established that the surface structure of knitted fabric affects the fading of colours with reactive dyes to varying degrees. It has been proven that a knitted fabric with a uniform smooth surface loses colour less under the action of light due to its ability to evenly distribute energy and reflect incident light compared to knitted fabrics with an uneven and rough surface. Based on the data obtained, the mechanism of the effect of light on knitted fabrics of various interlacing is given. Originality. The influence of the interlacing of cotton knitted fabric on the lightfastness of colours obtained by reactive dyes was studied. Practical value. According to the results of the study, interlacing of cotton knitted fabric were determined, which provide colours with reactive dyes with high resistance to light exposure, as well as interlacing, which require light-shielding treatment under the same conditions. [ABSTRACT FROM AUTHOR]

Background: Paper is one of the important inputs for the printing industry, and the most important leading parameter in the printing process is its brightness. Brightness can be brought to paper using coatings and sizing. Desired surface properties and, most importantly, surface roughness can be achieved by changing the contents of the coating and sizing of the materials it contains. The use of biomaterials is becoming more important in the paper industry, as they represent substances with a lower carbon footprint. Fish scales are already used as a filling material, cosmetic material and fish food, as well as for determining the age of fish. Methods: Fish scales were brought to different sizes by a milling process. Paper formulations including different amounts of fish scales were prepared with fish scales, and coatings on raw paper were subjected to test printings in IGT-C1, with formulations and physical characteristics of coatings such as brightness, lightfastness, strength, adhesion etc. being determined. Results: Regarding the value of yellowness, mixtures of 2.5%-10% can be used. The maximum value of brightness was obtained from a mixture of 10%. Aging visibly changed the colors. Conclusions: The coatings obtained were brighter than the initial coating compositions. The top quality formulation was the coating with 5% medium-sized fish scale particles. [ABSTRACT FROM AUTHOR]

Direct disazo dyes, R-salt derivatives, were synthesized and examined. The dyes were prepared by coupling of appropriate components with tetrazotized diacyl derivatives of aromatic diamines. Derivatives of dicarboxylic acids with the general formula HOOC―(CH2)n―COOH (n = 0 ÷ 4) were used as acylating agents. Photochemical degradation rates of dyes on dyed cotton fabric were studied. Compositions of azo-hydrazone tautomers, their aggregates, and their decay rates in UV-Vis light were determined. It was assumed that the length of aliphatic chain in the molecule affects the rate of its photochemical degradationT1/2, tautomeric composition, and dyes aggregation in azo and hydrazo forms. [ABSTRACT FROM AUTHOR]

An investigation for light exposure on pigments in low-oxygen environments (in the range 0-5% oxygen) was conducted using a purpose-built automated microfadometer for a large sample set including multiple samples of traditional watercolour pigments from nineteenth-century and twentieth-century sources, selected for concerns over their stability in anoxia. The pigments were prepared for usage in watercolour painting: ground and mixed in gum Arabic and applied to historically accurate gelatine glue-sized cotton and linen-based papers. Anoxia benefited many colorants and no colorant fared worse in anoxia than in air, with the exception of Prussian blue and Prussian green (which contains Prussian blue). A Prussian blue sampled from the studio materials of J.M.W. Turner (1775 − 1851) was microfaded in different environments (normal air (20.9% oxygen) 0, 1, 2, 3.5, or 5% oxygen in nitrogen) and the subsequent dark behaviour was measured. The behaviour of the sample (in normal air, anoxia, and 5% oxygen in nitrogen) proved to be consistent with the 55 separately sourced Prussian blue samples. When exposed to light in 5% oxygen in nitrogen, Prussian blue demonstrated the same light stability as in air (at approximately 21°C and 1 atmosphere). Storage in 5% oxygen is proposed for 'anoxic' display of paper-based artworks that might contain Prussian blue, to protect this material while reducing light-induced damage to other components of a watercolour, including organic colorants and the paper support. [ABSTRACT FROM AUTHOR]

Abstract: The fading characteristics of the AATCC Blue Wool L2 and L4 lightfastness standards were examined from the standpoint of wavelength sensitivity. Experiments were carried out by exposing a specimen to a narrow monochromatic band isolated from the dispersed polychromatic light emitted by a Xe lamp source. The wavelength sensitivity characteristics of Blue wool L2 and L4 lightfastness were determined on a radiant energy basis. Both Blue Wool Standards displayed peak maxima at 245 and 294 nm. The results indicated that UVA and UVB had a significant fading effect, whereas visible light caused fading to a small extent. Specific wavelengths caused Blue wool to significantly fade, suggesting that the total irradiated UV energy may not be an appropriate index. In addition, their spectral reflectances did not directly explain these characteristics of the standards. [Copyright &y& Elsevier]

Two easy laboratory methods for preparation of rare-earth orthophosphates (crystallisation from phosphoric acid solution and solid-state reaction with (NH4)2HPO4) were compared on the basis of the products’ properties with a focus on their application as new inorganic pigments. The preparation method has a significant influence on optical properties. The samples prepared by crystallisation have lighter and less rich colour and also change colour more under sunlight irradiation. The surface properties analysed by SEM and presence of a greater amount of phosphoric acid in the crystallisation procedure influence the pH and resistivity of aqueous extract of products and thus their corrosion-inhibition properties. The optical properties of rare-earth orthophosphates and their preliminary corrosion tests show their potential application as highly efficient corrosion-inhibition pigments. [ABSTRACT FROM AUTHOR]

9-arylated acridine-based derivatives (AUPAO & AUEA) with high visibility, fluorescence, and excellent lightfastness were synthesized in good yield. The molecules were characterized by 1H NMR, 13C NMR, HRMS and further investigated for photophysical properties. Initially, absorption and emission studies were carried out in wide-ranging polarity solvents to choose a solvent of interest for further investigations. Concentration-dependent studies were carried out in ethanol to determine an optimized concentration to study lightfastness studies. These molecules showed excellent lightfastness properties in solution form when compared to commercially available acridine orange. pH-dependent studies were also carried out to observe the behavior of cationic dyes in a wide range of pH to optimize pH for dyeing. The presence of extended conjugation at the 9th position and additional four methoxy groups resulted in highly fluorescent dyes with excellent quantum yield. The steric interactions, higher twist, and unrestricted rotation of the conjugation pathway between the aromatic ring at the 9th position and the acridine core decreased the transition probability and energy transfer that helped improve the lightfastness. The introduction of a hydroxyl group in AUEA increased the solubility and helped in controlled dispersion while dyeing. Further, they were dyed on modacrylic fabric as high visibility fluorophores, and later the color coordinates, color strengths were measured. • 9-arylated acridine-based high visible fluorophores (AUPAO & AUEA) were synthesized in good yields. • These molecules showed a high molar absorption coefficient and fluorescence with more quantum yield. • These molecules are promising candidates with improved lightfastness when compared to acridine orange (AO). • The presence of aromatic ring at 9th position and four methoxy groups helped in increased fluorescence and quantum yield. • The presence of the hydroxyl group gave AUEA an advantage over AUPAO in solubility and diverse pH conditions. • These molecules also demonstrated good dyeing properties on modacrylic fibers. [ABSTRACT FROM AUTHOR]

Abstract: The photoexcited state of linear trans-quinacridone pigment nanoparticles, prepared by a reprecipitation method, was analyzed by time-resolved spectroscopy. The analysis showed that the S1 state of the linear trans-quinacridone nanoparticles undergoes a quantitative, non-radiative relaxation to the ground state with a time constant of about 100ps. By contrast, the S1 state of the molecular dispersion state (dilute solution state) was relatively long-lived (21ns). This, together with the intersystem crossing to T1 observed in the molecular dispersion state, clearly distinguished the nanoparticles from the molecular dispersion state. By comparing the two in terms of lightfastness, the nanoparticles were found to be much more lightfast than the molecular dispersion state. It was speculated that the superior lightfastness of the linear trans-quinacridone pigment nanoparticles was not due to the molecular structure but the facilitated S1 relaxation by the aggregation of the molecules. [Copyright &y& Elsevier]

In this study, a renewable polymeric material, refined oriental lacquer (ROL), used as a wood protective coating, and the Acacia confusa Merr. heartwood extractive, which was added as a natural photostabilizer for improving the lightfastness of ROL, were investigated. The best extract conditions for preparing heartwood extractives and the most suitable amount of addition (0, 1, 3, 5, and 10 phr) were investigated. The lightfastness index including brightness difference (ΔL *), yellowness difference (ΔYI), and color difference (ΔE *), and their applied properties of coating and film were measured. In the manufacture of heartwood extractives, the yield of extractives with acetone solvent was 9.2%, which was higher than that from toluene/ethanol solvent of 2.6%, and also had the most abundant total phenolic contents (535.2 mgGAE/g) and total flavonoid contents (252.3 μgRE/g). According to the SEM inspection and FTIR analysis, the plant gums migration to the surface of films and cracks occurred after UV exposure. The phenomena for photodegradation of ROL films were reduced after the addition of heartwood extractives. Among the different amounts of the heartwood extractives, the 10 phr addition was the best choice; however, the 1 phr heartwood extractive addition already showed noticeable lightfastness improvement. The drying times of ROL were extended and film performances worse with higher additions of heartwood extractives. Among the ROL films with different heartwood extractive additions, the ROL film with 1 phr addition had superior films properties, regarding adhesion and thermal stability, compared with the films of raw oriental lacquer. [ABSTRACT FROM AUTHOR]

Abstract: A series of new coumarin fluorescent dyes derived from arylsulfonation of the parent benzothiazole, benzimidazole and benzoxazole dyes have been synthesized in high yield. The dyes were successfully applied to polyester fabrics to give highly fluorescent greenish-yellow shades. Improvements in fastness to sublimation, washing and perspiration (both acidic and alkaline) were observed but there was no general improvement in lightfastness compared with the parent compounds. Molecular modeling studies (AM1, MM2, ZINDO calculations) were used to investigate relationships between the chemical structures, spectral properties and technical performance. [Copyright &y& Elsevier]

Abstract: As a new model system of dye-containing oil droplet of color paper, the dispersion of dye-containing oil droplet in water was successfully prepared by reprecipitation method, and was used for the analysis of photo-excited states of dyes used for color image formation in silver halide color photography. This model was applied to analysis of photo-excited states of yellow dye aggregates of 1,1-dioxo-1,2,4-benzothiadiazine series. It was found that the lightfastness of the yellow dye of this series is controlled by the degree of aggregation and the lifetime of S1 state of the aggregate. Based on the finding, we have succeeded in improvement of lightfastness of the dye by sterically hindering the aggregation and reducing the lifetime of the excited state. [Copyright &y& Elsevier]

Abstract: This paper explores some possibilities of using UV absorbers to improve lightfastness of inkjet prints. Up to 1-class increase in AATCC lightfastness was obtained by adding a UV absorber onto a printed fabric. This means that a designer, an artist or a textile/apparel producer can double the fading resistance of inkjet printed textiles to light by a simple treatment. Both water soluble and insoluble UV absorbers with benzophenone structures were examined. The effects of UV absorbers, their concentrations and application conditions on lightfastness improvement of reactive inkjet prints are discussed. [Copyright &y& Elsevier]

Photofading of 15 reactive azo dyes derived from H- (seven), J-, L-, R-, 2R-, γ-acids (three), pyrazoline and a reactive copper-complex dye on cellophane under wet conditions was examined to estimate the essential properties: photo-oxidisability (k0: the reactivity with molecular singlet oxygen), photosensitising ability (f) and photo-reductivity. The relationships between the essential properties of these dyes and the lightfastness (LF) as well as the perspiration-lightfastness (PLF) on cotton fabrics are discussed. A linear correlation between the logarithmic product, log (f k0), and the LF ratings of dyes on dry cotton fabric was found when plots of reactive dyes with low LF and those of the vat dyes examined in a previous paper were added because the ratings of 11 red dyes out of 15 dyes examined had a narrow range. It showed that LF of monoazo red reactive dyes on dry cotton fabric is very dependent on photo-oxidative fading. A linear correlation was also found between logarithms of f-values and the relative initial rates of photo-reductive fading, except for dyes with very high photosensitising ability. A conflicting relationship between the k0-values and the photo-reductivity could be shown for dyes derived from H- and γ-acids, an unsolved restriction on synthesis of azo dyes with excellent LF as well as PLF. Azo dyes derived from γ- and 2R-acids possess smaller f but larger k0 values than those derived from H-acids. The photofading of dyes on cotton fabrics in the presence of artificial perspiration was explained in terms of the essential properties. The substrates promoted photo-reduction and suppressed photo-oxidation. [Copyright &y& Elsevier]

Photodegradation characteristics of selected natural dyestuffs were investigated on the basis of solar radiant energy. UVA and UVB fluorescent lamps were also applied to examine wavelength dependencies on the fading characteristics. The natural dyestuffs were observed to have poorer lightfastness in the comparison with AATCC Blue Wool L2. The order of fading susceptibility to solar radiation is as follows: Turmeric > Weld > Madder > L2. Moreover, It was concluded that the natural dyestuffs were strongly sensitive to visible light as well as to UV rays and L2 would be faded by visible light to the small extent. These results provide an important key to understanding the poor lightfasteness of some natural dyestuffs. [Copyright &y& Elsevier]

Copper (II) salts were used as metallizing agents in the synthesis of new direct dyes for cotton. In this regard, direct dyes possessing ortho-propoxy, ortho′-hydroxy-substituted systems formed the corresponding dye–metal complexes. The complexes were characterized by neutron activation and spectrometric analyses and evaluated on cotton for color fastness. [Copyright &y& Elsevier]

Photostability of nine (seven anthraquinone and two thioindigoid) vat dyes on cellulosic films was examined. The ease (k0) with which the dyes were photo-oxidized was estimated by the relative fading of vat dyes on cellophane immersed in aqueous Rose Bengal solution on exposure, a condition resulting in only the photo-oxidative fading. The photosensitivity (f) was estimated by the relative fading of an aminopyrazolinyl azo vinylsulfonyl dye on cellophane dyed in admixture with vat dyes examined under the same conditions as above. The values of k0 were small, compared with those of reactive dyes, while those of f comparable. The lightfastness of nine vat dyes on dry cotton fabric had close correlation with log (f k0). This fact shows that the fading of vat dyes on dry cellulose occurs mainly by photo-oxidation on exposure in air. On exposure of vat dyes on cellulosic substrate in an aqueous anaerobic dl-mandelate solution, a condition resulting in only the photo-reduction, vat dyes displayed a colour change in the direction of the acid leuco-compounds, many of which returned to the original dyes by re-oxidation. Vat dyes with high photoreductivity showed the same colour change on dry cellulose by long exposure, implying that photo-oxidation occurs in the superficial part of fibre substrate and photo-reduction in the inner part. The photofading properties of anthraquinone vat dyes were attributed to the excited triplet T1(nπ*) state of the carbonyl groups. The quantum yields to T1(ππ*) was very small by an effective internal conversion of the exited singlet states. Since the ππ* absorption of the annelated anthraquinones with the large extinction coefficients shielded the carbonyl groups with the small coefficients from the nπ* absorption, the photofading of the vat dyes with the highest lightfastness became very small. As a result, those vat dyes perform the highest lightfastness. [Copyright &y& Elsevier]

We have examined the effect of two different classes of photostabilizers, UV absorber and hindered amine light stabilizer (HALS) on Nylon 66 to prevent the photo-oxidation of the polymer matrix and colour fading of the dye. Acid blue dyes, UV absorber and HALS were observed to impart photostability to Nylon 66. UV absorber and HALS showed photostability directly proportional to their relative concentration in the polymer whereas in case of dye, 0.2% w/w concentration was observed as the optimum concentration. Loss of UV absorber with photo-irradiation time was found to be inversely proportional to the UV absorber concentration in the polymer whereas the fading of the dye was directly proportional to its concentration in the polymer. UV absorber imparted higher lightfastness to the dye as compared to HALS. No influence of the substitution on pendant phenyl ring of anthraquinone acid blue dyes was observed for their photostabilizing efficiency. [Copyright &y& Elsevier]

Dyed polymers are prepared by mixing a polymeric material and a dye. For uniform dyeing it is necessary to grind a dye. Some dyes have such properties as hydrophilicity and tendency of dyes to form agglomerates, which negatively affect the dyeing process, require additional equipment. The method of structural polymer dyeing can eliminate these difficulties. The aim of our research is to study regularities of producing structurally-dyed alkyd resin, modified by oil. The scheme of obtaining the structurally-dyed resin, modified by oil can be represented as follows. Firstly, the reesterification of pentaerythritol by oil is carried out. At the second stage, azopigment is added to interesterificator. Then, we add the phthalic anhydride and glycerol and conduct the polycondensation up to the specified acid number. The possibility of obtaining structurally-dyed alkyd resin, modified by oil was shown. Structurally-dyed alkyd resin has high pigment properties and can be used as an oligomeric dye. [ABSTRACT FROM AUTHOR]

Pacific Islanders have traditionally used plants and other natural resources to craft paints, dyes, and other colorants. However, much of society today has transitioned to more accessible, inexpensive colorants, which oftentimes contain toxic pigments and harmful solvents that can be detrimental to human health and the environment. This study will explore using phytochemicals of plants indigenous to the Pacific as safe, natural watercolor paints. The objective of this study is to test the lightfastness of watercolors made from roots of the langiti (Ochrosia mariannensis), roots of the ladda (Morinda citrifolia), cambium of the binalo (Thespesia populnea), and aerial roots of the kaffo' (Pandanus tectorius). In this experiment, water-soluble pigments were extracted from the plant materials through solvent extraction, rotary evaporation, and freeze-drying. The extracted compounds were then bonded to a colorless mordant, potassium aluminum sulfate, through chemical precipitation. The resulting lake pigment was then dried and made into traditional natural watercolors using a mixture of gum arabic and honey. To test for lightfastness, natural watercolors and name-brand ASTM compliant watercolors were subjected to an accelerated UVA exposure test for 14 days. Furthermore, sections of the color swatches were covered to analyze color intensity without exposure to UVA light. Color differences were measured in CIE L*a*b* coordinates in two-day intervals using a spectrocolorimeter. Data obtained from the triplicated samples were compared by analysis of variance and mean and standard deviation were calculated. Research is currently being conducted and results will be examined and published at a later date. [ABSTRACT FROM AUTHOR]

Refined oriental lacquer (ROL) is a natural polymeric material with a satiny texture, elegant beauty, and high durability for wood furniture and handicraft finishing. However, its poor lightfastness, which results from the photo-degradation or photo-oxidation of its main component, catechol derivatives, must be improved for its widespread utilization. In this study, two experiments were performed. First, five types of antioxidants, including three primary antioxidants, such as 2,2′-methylenebis(6-nonyl-p-cresol) (coded as AO-1), 2,2′-methylenebis(6-tert-butyl-4-methylphenol) (AO-2), and bis [4-(2-phenyl-2-propyl) phenyl] amine (AO-N), and two secondary antioxidants, such as tris (2,4-ditert-butylphenyl) phosphite (AO-P) and dilauryl thiodipropionate (AO-S), were investigated to determine which is the most effective for improving the lightfastness of ROL. Secondly, the appropriate quantity of the best antioxidant, including 0, 1, 2, 3, 5, and 10 phr, was also determined. The lightfastness parameters, such as brightness difference (ΔL*), yellowness difference (ΔYI), and color difference (ΔE*), as well as other coating and film properties, were assessed. The results showed that the primary antioxidants had higher efficiency than secondary antioxidants for improving the lightfastness of ROL. Among the primary antioxidants, the 5 phr AO-N was the most effective at improving the lightfastness of ROL; however, 1 phr addition had already shown significantly improved efficiency. In addition, the drying time of ROL was extended and film properties decreased when increasing the content of AO-N, but the 1-phr-containing ROL displayed superior film properties, especially adhesion and bending resistance, compared with the raw ROL film. [ABSTRACT FROM AUTHOR]

Wet-white tanning system for chrome-free leather processing has been deemed as a feasible alternative from the source to effectively eliminate potential environmental and human health risks of conventional chrome tanning. This work presents a novel sustainable chrome-free leather processing based on lightfast wet-white tanning system of hydrolysable Tara tannins synergized with synthetic clay nanoplatelets (Laponite) and active aluminium salts (Lutan@ BN). The results show that the introduction of BN can significantly enhance the hydrothermal stability of wet-white leathers. The novel wet-white tanning system selected as 10% Tara–1% Laponite–3% BN for 2 h can endow the wet-white leathers with a shrinkage temperature (T s) above 95 °C. Moreover, Tara–Laponite–BN complexes can be in-situ formed on the surface of the collagen fibers or between collagen fibrils within the collagen fiber strands, stabilizing primary and conformational structures of the collagens. Notably, the incorporation of BN within the collagens can increase the isoelectric point (IEP) of the leather matrix and facilitate exhaustions of anionic post-tanning chemicals in chrome-free leather processing. The resultant leather exhibits pleasant pastel color, favorable light-fastness, and reasonable physical performances without containing restricted hazardous Cr(VI) and free formaldehyde in accordance with current Chinese standard requirements for furniture leather and European Union Eco-label criteria. These results will provide more perspectives for designing and rationalizing sustainable chrome-free leather processing towards eco-leather manufacture. Image 1 • A novel sustainable chrome-free leather processing has been developed. • The introduction of aluminium salts enhances exhaustions of anionic chemicals. • The resulting chrome-free leather exhibits improved physical properties. [ABSTRACT FROM AUTHOR]

In this study, we examine the chemical stability of two disazo dyes, namely Solvent Red 19 and 23 (SR 19 and SR 23), under simulated conditions. Both dyes are considered to be chemically stable under normal exploitation conditions and therefore, are used extensively as excise duty components that enable a rapid visual verification of the tax levels that were imposed on fuel products as well as identifying fuel usage. However, the results from this study confirmed that the colour of the samples that had been fortified with either SR 19 or SR 23 fades under the influence of external conditions such as UV-A irradiation and temperature over time. The UV-A irradiation was the dominant factor that was responsible for the colour of the samples to fade in two designed experiments that were carried out independently for two model systems. The analysis of the UV/Vis and fluorescence spectra as well as the interpretation of the changes that were observed in the chromatographic profiles provided substantial evidence that the colour fading was caused by the photodegradation of the disazo dyes, which also occurs in non-polar media including fuel products. SR 19 is more stable than SR 23. • Solvent Red 19 and 23 are unstable when exposed to UV-A irradiation. • Solvent Red 19 and 23 undergo photoinduced degradation. • Solvent Red 19 is more stable than Solvent Red 23. • Recommended spectrophotometric method cannot settle the fuel counterfeiting problem. [ABSTRACT FROM AUTHOR]

Five azo dyes with ESIPT unit were used to study their application properties. These dyes were used for coloration on polyester (PET), acrylic (AC) and nylon (NY) fabrics. The various properties of fastness, UV blocking, UV protection properties were investigated. Elecrophilicity index was calculated for comparing with the trends in lightfastness properties on PET, NY and AC fabrics. The azo disperse dyes containing electron withdrawing group in 3d and 3e showed the highest electrophilicity index (7–7.05) and lightfastness (6–7 and 7). The electrochemical characteristics of these dyes were calculated using cyclic voltammetry (CV) and density functional theory. Oscillator strength, vertical excitation, orbital contribution, HOMO-LUMO, and MEP were calculated from experimental and theoretical results (time-dependent density functional theory). Dye 3a shows the highest band gap (2.88 eV) and dyes 3b, 3c, 3d, 3e showed the lowest band gap (2.60 eV, 2.66eV, 2.72eV, 2.72eV) respectively. • Dyes 3a-3e were successfully applied on polyester, nylon, acrylic fibres. • Lightfastness properties correlated well with electrophilicity index. • Dye 3a shows the highest band gap (2.88 eV). • Electrochemical properties were calculated by cyclic voltammetry. [ABSTRACT FROM AUTHOR]

Introduction: Paper is the most important material of the printing industry and is being improved due to the increasing needs of industry. The most important process to improve the optical and physical properties of paper is the surface coating. Paper has a smoother and opaquer surface with surface coating. In addition, brightness, whiteness, and yellowness values are improved with surface coating. Ultraviolet (UV) light in sunlight causes changes in the structure of the paper and coating chemicals and accordingly causes yellowing. Para-amino benzoic acid (PABA), due to its chemical structure, is a UV-blocking agent used in sunscreen creams. Methods: The effect of PABA on paper gloss, yellowness, and lightfastness values was investigated by adding it into the surface coating formulation. For this purpose, coating formulations were prepared with cationic starch and 3%, 5%, and 7% PABA; coatings were applied to the paper according to laboratory condition standards. Coated papers were printed with an IGT-C1 lab-type offset printability device with magenta ink. The printed papers were then exposed to a light fastness test with Solarbox. The color, brightness, and yellowness values of all samples before and after lightfastness were measured with an X-Rite spectrophotometer. The gloss of coated and printed paper sample values was measured with a BYK-Gardner glossmeter. Results: The gloss values of paper to which PABA was added, increased; however, it was determined that these gloss values decreased after the lightfastness test. Conclusions: PABA-added cationic starch coatings are more affected by UV light than cationic starch coatings. [ABSTRACT FROM AUTHOR]

Introduction: Paper is the most important material of the printing industry and is being improved due to the increasing needs of industry. The most important process to improve the optical and physical properties of paper is the surface coating. Paper has a smoother and opaquer surface with surface coating. In addition, brightness, whiteness, and yellowness values   are improved with surface coating. Ultraviolet (UV) light in sunlight causes changes in the structure of the paper and coating chemicals and accordingly causes yellowing. Para-amino benzoic acid (PABA), due to its chemical structure, is a UV-blocking agent used in sunscreen creams. Methods: The effect of PABA on paper gloss, yellowness, and lightfastness values   was investigated by adding it into the surface coating formulation. For this purpose, coating formulations were prepared with cationic starch and 3%, 5%, and 7% PABA; coatings were applied to the paper according to laboratory condition standards. Coated papers were printed with an IGT-C1 lab-type offset printability device with magenta ink. The printed papers were then exposed to a light fastness test with Solarbox. The color, brightness, and yellowness values   of all samples before and after lightfastness were measured with an X-Rite spectrophotometer. The gloss of coated and printed paper sample values was measured with a BYK-Gardner glossmeter. Results: The gloss values   of paper to which PABA was added, increased; however, it was determined that these gloss values   decreased after the lightfastness test. Conclusions: PABA-added cationic starch coatings are more affected by UV light than cationic starch coatings. [ABSTRACT FROM AUTHOR]