Dry Pigment Research Articles

An Investigation into the Suitability and Stability of a New Pigmented Wax-Resin Formulation for Infilling and Reintegration of Losses in Paintings

ABSTRACT A new Pigmented Wax-Resin (PWR) formulation for infilling and reintegration of losses in paintings is introduced and tested for its suitability and stability. It consists of a mixture of Cosmoloid H80 microcrystalline wax and Regalrez 1126 hydrogenated hydrocarbon resin with dry pigments and/or fillers. Unlike other PWR formulations, including those sold by Gamblin Conservation Colors, it does not contain beeswax. Beeswax is reported to develop bloom and to corrode copper supports. The authors share methodologies and techniques used to characterize and assess the suitability of the new formulation in terms of its physical and optical properties, and to assess its stability to fluctuating relative humidity and temperature, particularly high temperatures. The new formulation was evaluated for its workability, opacity, and flexibility and for its compatibility with a selection of varnish coatings and inpainting media. Results showed that 1.5 parts of Cosmoloid H80 to 1 part of Regalrez 1126 (by weight), mixed with pigments and/or fillers, is a viable alternative to other infilling and inpainting media. It has good optical and working properties, a suitable degree of hardness, and remains stable during fluctuations in relative humidity and temperature, as well as to temperatures as high as 70°C.

Alkyds with artistic applications based on drying oils, multifunctional polyalcohols and different polybasic acids

AbstractToday's requirements in the art field have challenged researchers to create artistic paintings with attractive appearance and long‐term color stability. Alkyd‐based art mediums have become an important group in the art field, because of their similar characteristics to traditional oils and exceptional drying properties. In this work, high solid alkyd‐based art mediums have been synthesized by the monoglyceride and acidolysis processes. Multifunctional polyols and high unsaturated fatty acid sources were compared and used for alkyd synthesis. The use of a non‐traditional oil of Peruvian origin is proposed. Resins have been characterized according to their physicochemical (acid number, viscosity, color and density) and drying properties. Drying tendencies were verified with the use of quartz crystal microbalance. Also, the behavior of the art mediums mixed with commercial oil paintings and a dry pigment, have also been evaluated. Results indicate that resins containing the polyol with the highest functionality are more viscous and have fewer tendencies to yellowing, while non‐traditional Peruvian oil is the best option for creating light‐colored art mediums. Alkyd mediums prepared by the monoglyceride method gave to oil paintings better characteristics and drying behavior on canvas.

Tolerance of metal halide perovskites to mechanical treatment enables the fabrication of patterned luminescence nano- and microstructures

The ancient technology of colouring by mechanical rubbing of a dry pigment onto surfaces can be applied to metal halide perovskites, enabling the fabrication of highly luminescent templated micro and nano arrays.

Biological activity of Arum Cyreniacum (Araceae) and potential use as Bioherbicide

The present investigation aims was carried out to study the biological activity of aqueous extract and shoot crude powder of Arum cyreniacum (ACSAE and ACSCP) on some germination and growth parameters (germination bioassay experiment) besides major physiological, and biochemical processes (pot experiment) In Hordeum vulgare (crop species) and Phalaris minor (weed species) of different concentrations of A. cyreniacum on germination percentage (GP), coleoptile (CL) and radicle (RL) lengths, seedling shoot and root length seedling fresh and dry weight, some nutrients (N, K, Na, Cu, Fe, and Ni ), and photosynthetic pigments .Generally, the effect of the all concentrations levels of the extract on (GP), (CL) and (RL) on H. vulgare seeds was ineffectively decreased with increasing the concentrations of A. cyreniacum while the percentage was significantly decreased with increasing the concentrations of the with P. minor. All concentrations levels of the extracts reduced coleoptile (CL) and radicle (RL) lengths of H. vulgare. Likewise, the reduction in the two parameters was documented in P. minor. Were more affected in P. minor compared to H. vulgare. There was a significant within the concentration of micronutrients as well as the entire photosynthetic color substance of P. minor seedlings grown in ACSCP. Treatment with ACSCP had a more negative effect on total nitrogen in P. minor than on H. vulgare. Keywords: R Hordeum Vulgare; Growth Parameters; Nutrient Content; Photosynthetic Pigments

Shedding Light on Daylight Fluorescent Artists’ Pigments, Part 1: Composition

ABSTRACT The vivid colors and luminosity of daylight fluorescent pigments have secured them a spot on the artists’ palette since their inception in the 1930s. However, these colorants pose unique challenges to conservators due to their complex formulations consisting of a mixture of dyes and optical brighteners impregnated in a formaldehyde-rich polymer resin. Furthermore, these pigments are often intended for display under blacklights, which accelerate fading and polymer degradation reactions and pose demanding inpainting requirements of conservators. This research provides a comprehensive report on the dye composition of pigments made by the major European and American manufacturers, as well as those sold as artists’ dry pigments. Differences in the dyes and additives were identified for the first time using liquid chromatography with mass spectrometry, while subtle variations in the resin matrix were revealed using infrared spectroscopy. Specific identification of the dye and matrix components can differentiate the pigment sources and be taken advantage of in conservation treatments. This is demonstrated in the analysis of Stefano Castronovo’s fluorescent Mona Lisa painting on a Stephen Sprouse designed silver leather motorcycle jacket. Analysis of a mid-twentieth century designer’s manual produced by the Day-Glo Corporation revealed how the pigments’ dye components have shifted over time.

Fiber Optic Reflection Spectroscopy-Near-Infrared Characterization Study of Dry Pigments for Pictorial Retouching.

A deep comprehension of composition of pigments, employed nowadays in the field of pictorial retouch is considered essential for a deeper knowledge of their behavior with time once applied on artifacts. A commercially available set consisting of 27 pigments employed for the conservation of both historical and contemporary artworks has been characterized through Reflectance Spectroscopy in the VIS and NIR spectral range. The pigments included in the investigated set are classified into four categories: (i) dyes and colors from plants, (ii) modern pigments, (iii) pigments of own production and historical pigments, and (iv) natural earths. Recorded spectra were interpreted with the aim to detect existing coloring and filling phases and obtained results were compared with available data sheets: some inconsistencies were found, as well as lack of some compounds among the reported ones. Attributions were found for many features, even if in some cases detailed information for a comparison was not found in the literature, especially regarding NIR spectra. The proposed paper aims to provide a useful tool for the study of real artworks with a detailed overview of material characteristics in the visible and near infrared spectral range.

Ommochromes from the Compound Eyes of Insects: Physicochemical Properties and Antioxidant Activity.

The objective of this study was screening of ommochromes from the compound eyes of insects and comparison of their antioxidant properties. Ommochromes were isolated in preparative quantities from insects of five different families: Stratiomyidae, Sphingidae, Blaberidae, Acrididae, and Tenebrionidae. The yield of ommochromes (dry pigment weight) was 0.9-5.4% of tissue wet weight depending on the insect species. Isolated pigments were analyzed by high-performance liquid chromatography and represented a mixture of several ommochromes of the ommatin series. The isolated ommochromes displayed a pronounced fluorescence with the emission maxima at 435-450 nm and 520-535 nm; furthermore, the emission intensity increased significantly upon ommochrome oxidation with hydrogen peroxide. The ommochromes produced a stable EPR signal consisting of a singlet line with g = 2.0045-2.0048, width of 1.20-1.27 mT, and high concentration of paramagnetic centers (> 1017 spin/g dry weight). All the investigated ommochromes demonstrated high antiradical activity measured from the degree of chemiluminescence quenching in a model system containing luminol, hemoglobin, and hydrogen peroxide. The ommochromes strongly inhibited peroxidation of the photoreceptor cell outer segments induced by visible light in the presence of lipofuscin granules from the human retinal pigment epithelium, as well as suppressed iron/ascorbate-mediated lipid peroxidation. The obtained results are important for understanding the biological functions of ommochromes in invertebrates and identifying invertebrate species that could be used as efficient sources of ommochromes for pharmacological preparations to prevent and treat pathologies associated with the oxidative stress development.

From Wine to Print: Reconstruction of Frankfurt Black Pigment and Intaglio Printing Ink

ABSTRACT ‘Frankfurt Black' made of charred wine lees was often preferred above other charcoal pigments for intaglio printing in 17th to 19th centuries primary sources. As no samples of the dry pigment survive, it was experimentally recreated. Wine lees were charred according to historical instructions to determine appropriate conditions for dry pyrolysis (380°C, 300 min T). The pigment was ground with burnt oil varnishes prepared according to Abraham Bosse’s 1649 manual on etching and engraving. Reconstructed Frankfurt Black was compared to hand-ground inks made with different plant black pigments and modern bone black printing ink. Impressions were made from an etched plate and compared for their colour, contrast, clarity of lines and details. Generally, Frankfurt Black ink displayed the properties described in historical sources: deep dark colour and a soft texture. The ink resembled modern inks in print. The study illustrates how the choice and manufacture of historical ink constituents can affect the appearance of an intaglio print.

Phytoremediation of nickel polluted ecosystem through selected ornamental plant species in the presence of bacterium Kocuria rhizophila

The present study was conducted to find out the role of Consolida ambigua and Calendula officinalis L. ornamental plants along with Kocuria rhizophila bacterium in phytoremediation of the nickel contaminated soil. One group of ornamental plants was grown in control environment (C), while the other groups were subjected to stress conditions i.e., Treatment with Bacteria (T1), Treatment with Bacteria + Chelator (T2) and Treatment with Chelator (T3). Nickel Chloride (100 mg/kg) and citric acid (5 mM) were applied when the plant species started its normal photosynthetic activity. Preliminary results showed that plant biomass i.e., plant height (cm), fresh and dry weights (g), proline content (µg/g) and photosynthetic pigments (mg/g) were significantly increased with co-application of bacteria and citric acid as compared to non-inoculated and inoculated plant species. The growth pattern observed in order of T2 > T1 > T3 > C. The statistical significant growth with T2 at p ≤ 0.05 suggested the role of Consolida ambigua and Calendula officinalis L. ornamental plants in association with Kocuria rhizophila bacterium were beneficial for phyto-extraction purposes. It was concluded that the aforementioned plants can safely be grown for phytoremediation purposes to reduce soil pollution in term of heavy metal accumulation.

Putrescine affects tomato growth and response of antioxidant defense system due to exposure to cinnamic acid

ABSTRACTThe present study deals with the mitigating effects of putrescine (Put) against cinnamic acid (CA). Cinnamic acid in root and shoot exudates of tomato (Solanum lycopersicum L.) acts as an autotoxin, inhibiting growth and metabolic activities. Put has significant role in plant growth and development, as well as in defense against abiotic and biotic challenges. There are no reports on mitigation of allelopathic effects due to CA by Put. Tomato seedlings exposed to CA decreased root and shoot length, fresh and dry weights, photosynthetic pigments, protein and sugar contents, and nitrate reductase activity. These parameters increased when Put were applied in combination with CA and alone. Lipid peroxidation enhanced in seedlings treated with CA, but decreased in combined CA-Put treatment. Histochemical staining indicated that CA-induced oxidative damage which is evident from the presence of reactive oxygen species (ROS) such as O2– and H2O2 in tomato leaves. Put decreased ROS activity and plays promising role in regulation of antioxidant enzyme activities against production of free radicals and improved seedling growth exposed to CA. Put induced tolerance of tomato seedlings to CA autotoxicity was reflected through enhanced growth of the seedlings. Our findings reveal that Put is efficient to mitigate the allelopathic and adverse effects of CA and buttressed the defense system of tomato and eliminated the autotoxic effects of endogenous CA in tomato.

The role of agar gel in treating water stains on acrylic paintings: Case study of Composition, 1963 by Justin Knowles

ABSTRACTThis paper describes the historic context and explains the treatment rationale for minimizing disfiguring water stains on a large-scale, acrylic dispersion canvas painting: Composition, 1963, by British artist Justin Knowles. Composition is a brightly colored, hard-line geometric abstraction juxtaposed against an unpigmented acrylic dispersion-sized linen canvas. Accidental water damage produced tidal stains across the sized canvas, rendering it unexhibitable. Investigations into the relationship between materials and meaning in Knowles’ work, alongside literature on the cleaning of acrylic dispersion paintings, textiles, and works on paper facilitated the development of a tailored cleaning treatment involving the use of agar gel as an aqueous delivery system, which minimized risk to the painting materials, whilst facilitating a satisfactory reduction and subsequent visual integration of the water stain. As a final stage, a number of retouching media commonly used on acrylic paints were evaluated, and a successful method was determined using Aquazol 50 and dry pigments. The success of retouching was also evaluated via visual assessment, highlight-based RTI, and digital microscopy (HIROX). As a result of this collaborative approach, this important work has been successfully returned to displayable condition.

Diallel analysis and heterosis components in paprika peppers

The aim of this study was to quantify and assess the components of heterosis in paprika hybrids related to yield, capsanten pigment content (estimated as ASTA degrees) and resistance to Phytophthora capsici, and to identify parental lines with high general combining ability (GCA) to be used in future breeding programmes and/or to obtain new hybrids. Fifteen hybrids were obtained through a complete diallel cross (reciprocal hybrids excluded) among six proprietary paprika breeding lines from HortiAgro Sementes S.A., four of which originally introduced from Peru (P1=PIM 032-03; P2=PIM 033-11; P3=PIM 034-19; P4=PIM 035-01) and two from the U.S.A. (P5=PIM 036-08; P6=PIM 037-18). Epistatic gene action was involved in the expression of heterosis for fresh and dry yields and carotenoid pigment contents, and heterosis was predominantly in the direction of higher yields. No significant heterosis effects were detected for resistance to P. capsici, and gene action was of incomplete dominance for the resistant phenotype. The parental lines P1 and P5 showed high GCA values for all characters, and may be used in breeding programmes to obtain new improved lines or for the production of higher yielding hybrids. The most promising hybrid was P3xP5, which outperformed the standard cultivar “Papri Queen” in fresh (68 t ha-1) and dry (10 t ha-1) fruit yields and ASTA degrees (157), in addition to being resistant to P. capsici. The parental line P5, as well as the hybrids in which it participated as a parent were assessed as resistant to P. capsici.

Colorimetric analysis of thermochromic samples in different forms employing a digital camera

The calibrated and characterised digital camera was used for the recording of a dynamic colour change of thermally treated three-component leuco dye based thermochromic samples in various forms – bulk system, dry pigment, water- and solvent-based ink formulations, and their dry layers coated on different paper substrates. The study has proved that the proposed approach enables to examine the thermochromic behaviour through the individual stages of the thermochromic coating preparation process. The measured path in CIELAB colour space and derived characteristics of the dynamic colour change were obtained with higher time-temperature resolution than with previously employed methods, enabling to observe even the less distinct features. The most significant differences were related to the length and complexity of the colour path. Dry layers of the water-based thermochromic ink coated on papers had higher values of the total length of the path and the total colour contrast than the layers of the solvent-based ink. The colour of water-based coatings had higher chroma and also it was less influenced by paper substrate. When compared to the bulk thermochromic system, the dry pigment and dry ink layers on paper substrates exhibited a larger width of a hysteresis loop at the decolouration limit, mainly due to the decrease of the temperature at which the colouration starts on cooling.

Effect of CO2 elevation and UV-A radiation on growth responses of Zinnia, Petunia, Coxcomb, and Marigold

<p>In order to evaluate the effect of CO<sub>2</sub> elevation and UV radiation on growth responses of zinnia, petunia, coxcomb, and marigold, a study was conducted in 2015 at Arsanjan Islamic Azad University, Iran. The experimental design was factorial arranged in completely randomized design with three replications. Treatments were included four ornamental species (zinnia, petunia, coxcomb, and marigold), CO<sub>2</sub> concentration at two levels (350 and 700 ppm), and UV radiation at two levels (with and without UV radiation). Results showed that elevating of CO<sub>2</sub> concentration from 350 ppm to 700 ppm increased morphological and physiological characters of C<sub>3</sub> plants, especially marigold. Meanwhile, increasing CO<sub>2</sub> concentration from 350 ppm to 700 ppm, decreased effects of UV damage on plants’ morphological and physiological characters. The highest leaf number, shoot dry mass, plant height and water use efficiency of C<sub>4</sub> plant (coxcomb flower) were observed at 350 ppm of CO<sub>2</sub> concentration without UV radiation while, the highest leaf number, shoot dry mass and leaf pigments of C<sub>3</sub> plants (zinnia, petunia, and marigold flower) were obtained at 700 ppm of CO<sub>2</sub> concentration without UV radiation. The results showed that the activity of catalase and peroxidase enzymes under UV radiation was increased in all of plants. Overall, it is concluded that, the recognition of plants resistant to UV radiation and high levels of CO<sub>2</sub> concentration in the future may be better for environmental production and distribution as ornamental plants in town landscapes, where ecophysiological traits should be considered.</p>

Auxins Regulations of Branched Spike Development and Expression of TFL, a LEAFY-Like Gene in Branched Spike Wheat (Triticum aestivum)

Branched spike wheat is a hexaploid germplasm with branched rachis on its main rachises, and the crucial period for branched rachises occurrence and development is just after the two ridges stage of shoot apex. Natural [indole-3-acetic acid (IAA), indole-3butyric acid (IBA)] and synthetic [(1-naphthaleneacetic acid (NAA), 2,4-Dichlorophenoxyacetic acid (2,4-D)] auxins were applied at this period to investigate the spike traits, seedling growth and photosynthesis related characters and expression of a putative homologue of the LEAFY in branched spike wheat. The four types of experienced auxins induced similar effects on these foresaid characters, although the impact extents were different among the auxins treatments. More branched rachis, spikelets, fertile florets and longer branched rachis were obtained in plants with IAA and IBA at 0.1 mM or NAA and 2,4-D at 1.0mM than those plants with no auxin treated. Auxin treatments also increased fresh and dry mass, photosynthetic pigment and parameters. TFL, a LEAFY-like gene was cloned in branched spike wheat and TFL mRNA expression was quantified using real-time reverse transcriptase-PCR. Application of the auxins accelerated the rise in TFL expression during the periods of branched rachises occurrence and extension. The data supports the hypothesis that auxins play a central role in the regulation branched spike development and TFL might correlate with the development of branched rachises in branched spike wheat.

The making of Mark Rothko's Harvard Murals

Mark Rothko's Harvard Murals are a series of paintings on canvas commissioned by Harvard University and created in the early 1960s. The present study investigates Rothko's creative process, materials, and technique with ultraviolet and infrared imaging, analytical chemistry, cross-sectional analysis, and comparisons with the literature. Infrared and Raman spectroscopy imaging of cross sections help with the chemical mapping of the paint stratifications. A comparison of paper studies, studies on canvas, and the final five works installed give a detailed insight into Rothko's editing process. The intimate relationship between works on paper and canvas is traced by uncovering a back and forth between the two media, and the mixing of dry pigment with binder is a common theme for works on both supports. Motif developments, changes, and distinct painting campaigns become apparent with ultraviolet induced visible fluorescence imaging and infrared reflected infrared digital photography. Color measurements and microfading experiments give insight into the stability and light sensitivity of the materials used by Rothko in the Harvard Murals.

Identification of copper phthalocyanine blue polymorphs in unaged and aged paint systems by means of micro-Raman spectroscopy and Random Forest

Copper phthalocyanine (CuPc) blues (PB15) are largely used in art and industry as pigments. In these fields mainly three different polymorphic modifications of PB15 are employed: alpha, beta and epsilon. Differentiating among these CuPc forms can give important information for developing conservation strategy and can help in relative dating, since each form was introduced in the market in different time periods. This study focuses on the classification of Raman spectra measured using 532nm excitation wavelength on: (i) dry pigment powders, (ii) unaged mock-ups of self-made paints, (iii) unaged commercial paints, and (iv) paints subjected to accelerated UV ageing. The ratios among integrated Raman bands are taken in consideration as features to perform Random Forest (RF). Features selection based on Gini Contrast score was carried out on the measured dataset to determine the Raman bands ratios with higher predictive power. These were used as polymorphic markers, in order to establish an easy and accessible method for the identification. Three different ratios and the presence of a characteristic vibrational band allowed the identification of the crystal modification in pigments powder as well as in unaged and aged paint films.

Various Applications of Seaweed Improves Growth and Biochemical Constituents of Zea Mays L. and Helianthus Annuus L.

In this study, the effect of seaweed on the growth of Zea mays L. and Helianthus annuus L. was investigated. Seeds of the plants have been soaked for 6 hours in 0.5% Gracilaria corticata and 1.0% Enteromorpha flexuosa aqueous extract. The presoaked seeds were sown both in soil irrigated monthly with aqueous extract and in soil mixed with powdered seaweeds. Growth parameters of plants were studied after 60 days of growth. The results revealed that both applications of G. corticata and E. flexuosa enhance shoot length, root length, shoot and root dry weights, photosynthetic pigments, carbohydrate and protein contents, and nutrient uptake. The maximum growth was observed with irrigation by E. flexuosa extract. The element constituent [nitrogen (N), phosphorus (P), potassium (K+), calcium (Ca2+), magnesium (Mg2+), iron (Fe3+), manganese (Mn2+), and zinc (Zn2+)] and phytohormones [Indole-3-acetic acid (IAA), gibberellins, and cytokinins] of E. flexuosa extract and powder was higher that of G. corticata. Of the two seaweeds tested, E. flexuosa exhibited better responses.

Effect of Salt Stress on Different Growth and Biochemical Attributes in Two Canola (Brassica napus L.) Cultivars

A pot experiment was conducted to appraise the differences in salinity tolerance in two canola cultivars (Shiralec and Dunkeld). The experiment was laid out in completely randomized design with five replications. Four salinity levels [0, 120, 150, and 180 mM sodium chloride (NaCl)] were used in this study. Salt stress caused a marked decrease in plant fresh and dry masses, photosynthetic pigments, and anthocyanins and increase in malondialdehyde (MDA), hydrogen peroxide (H2O2), and leaf phenolics. We have observed that salt tolerance ability of cv. Shiralec is greater than that of Dunkeld in terms of lower salt-induced decline in fresh and dry masses, photosynthetic pigments, lower MDA, H2O2 contents, and greater leaf phenolics.

AN INVESTIGATION INTO KANDINSKY'S USE OF RIPOLIN IN HIS PAINTINGS AFTER 1930

Vasily Kandinsky worked in a variety of media throughout his long career, and it appears from technical examinations and from his writings that he experimented with and manipulated his materials and techniques. This article describes the scientific investigation of five paintings dated after 1930, four of which were recorded by the artist as containing “huile + rip” (“rip” being thought to refer to the renowned brand of oleoresinous enamel paint Ripolin or perhaps to another similar enamel type paint mixed with other media). Following a thorough non-invasive investigation of the paintings with XRF, selected paint samples were analyzed with FTIR spectroscopy, optical and polarized light microscopy, and SEM with energy dispersive x-ray spectroscopy. The results were compared to an extensive database of reference enamels and artist tube paints from the same era along with actual paints left by the artist in his studio. This study draws attention to the artist's complex use of mixed media, which if the artist's statements are accurate, may well have included mixtures of oleoresinous enamel paints and fine artist's tube paints, occasionally supplemented with dry pigments, used together with artists’ oils on the same painting.