Iron-containing Pigments Research Articles

Calcium antimonate: A new discovery in colour palette of Paestum wall paintings

During a restoration and diagnostic campaigns carried out on Paestum funerary slabs belonging to the Lucanian funerary art, calcium antimonate (CaSb2O6) was detected for the first time in the pictorial layers. This artificial pigment, widely employed as opacifier both in ancient glass and glaze covering clay objects, was found in the wall paintings, regardless of the colour, supporting the hypothesis of an intentional addition of calcium antimonate to the pigments and the involvement of ceramic painters.A multi-analytical approach was performed on 32 funerary slabs (6th – 3rd century BCE), currently located at the National Archaeological Museum of Paestum (Italy) using both polarized light microscopy and environmental scanning electron microscopy equipped with energy dispersive X-ray spectrometer, micro X-ray fluorescence, micro Raman spectroscopy, Fourier Transform Infrared spectroscopy and powder X-ray diffraction.The results confirmed the use of a limited number of pigments, usually applied with fresco technique, although in many cases the stratigraphy of the painted layer showed morphology of mezzo fresco technique, but no organic binders were found. The hues of vegetal decorations were obtained using green earth, sometimes Egyptian blue mixed with yellow ochre, carbon and bone blacks, and orpiment. The alteration of green earth and other iron-containing pigments are likely responsible for the discolouration of the original hues. In red paints, hematite and red ochre are frequently associated with ilmenite, a typical volcanic mineral. Egyptian blue was used in blue paints while in black paints it was mixed with carbon and bone black pigments.

The Samuel F. B. Morse statue in Central Park: scientific study and laser cleaning of a 19th-century American outdoor bronze monument

Many of Central Park’s bronze statues were coated with lacquer as a protective measure between the late 1970s and early 1990s. In several cases, these coatings outlasted their performance life and were no longer adequately protecting the sculptures. In 2010, a cyclical campaign to remove and refurbish the coatings provided an opportunity to closely assess the condition of de-coated surfaces and to develop suitable, sustainable treatment approaches. The Samuel F. B. Morse statue, created in 1870 by Byron Pickett, commemorates the 19th-century painter and inventor known for the telegraphic code that bears his name. Initially, samples from this statue were collected on the field and analyzed with various techniques to characterize the degradation products that were heavily affecting its surface and the organic coatings used to protect the bronze. Various corrosion species, mainly sulfates and chlorides, were identified by X-ray powder diffraction (XRD), while pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) revealed that the organic coatings were based on mineral wax and acrylics. These results informed a decision to relocate the statue to a controlled workshop space to aid in the manipulation of the large figure and optimize cleaning by laser ablation. Treatment was monitored through three campaigns of analysis using portable X-ray fluorescence (pXRF) spectroscopy, performed on select locations, to characterize the extent of corrosion across the sculpture’s surface and monitor changes on the target areas throughout the cleaning. Following the initial phase of treatment, pXRF showed the substantial removal of iron- and lead-rich compounds from the brownish-toned coating and atmospheric pollution deposition. In the subsequent treatment phases, variations in the relative amounts of sulfates and chlorides were noted and further investigated through the examination of a cross section by means of scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS). Based on the findings of iron-containing pigments in the organic coating, a decision to apply a new, similar, translucent, brown-toned coating containing such coloring materials was made to achieve the desired visual nuance for the finish and provide additional corrosion protection to the bronze. Scientific analysis on the Morse statue has helped characterize its materials, methods of fabrication, and current conditions on a microscopic scale; in addition, it has guided the means and methodologies of treatment and relays essential information useful for future preservation.

Iron-Containing Pigments by SHS Method

Iron-Containing Pigments by SHS Method

Colourful earth: Iron-containing pigments from the Hellenistic pigment production site of the ancient agora of Kos (Greece)

The red, brown, yellow and green pigment lumps from the Hellenistic pigment production site of the ancient agora of Kos (Dodecanese, Greece) are the focus of this paper. A selection of pigments is examined through a combination of analytical techniques, including SEM-EDS on uncoated samples, X-ray powder diffraction, FTIR and pRaman spectroscopy. Through the study of raw pigments deriving from the context of a production site, the aim is to approach pigment manufacturing contextually during the Hellenistic period. The examined red pigments were characterised as red earths (rubricae, μίλτοι), with their colour primarily attributed to hematite. However, significant variance was observed in their chemical and mineralogical composition, reflecting on their final colour. Interestingly, two of the red samples contained lead tetroxide in addition to hematite. The colour of the brown pigments was attributed to a complex mixture of iron oxides. The chemical and mineralogical composition of the two yellow lumps showed that they are of different origin; the first, composed of goethite and quartz, can be characterised as a yellow earth (sil, ὢχρα) and the second corresponds to the mineral jarosite. A green-coloured lump was characterised as a type of celadonitic rock. The variance in the composition of the examined pigments indicates the treatment techniques carried out at the site and the preferences of the local craftspeople. The finds from the Koan workshop illustrate the complex and sophisticated nature of pigment production, suggesting an intertwined relationship with mining and metallurgy.

Efficiency Assessment of Using Flammable Compounds from Water Treatment and Methanol Production Waste for Plasma Synthesis of Iron-Containing Pigments

This article describes the possibility of applying the low-temperature plasma for obtaining iron-containing pigments from water purification and flammable methanol production waste. In this paper were calculated combustion parameters of water-saltorganic compositions (WSOC) with different consists. Authors determined the modes of energy- efficient processing of the previously mentioned waste in an air plasma. Having considered the obtained results there were carried out experiments with flammable dispersed water-saltorganic compositions on laboratory plasma stand. All the experimental results are confirmed by calculations.

Enhancement of immunohistochemical detection of Salmonella in tissues of experimentally infected pigs.

Salmonella Typhimurium is one of the main pathogens compromising porcine and human health as well as food safety, because it is a prevailing source of foodborne infections due to contaminated pork. A prominent problem in the management of this bacteriosis is the number of subclinically infected carrier pigs. As very little is known concerning the mechanisms allowing Salmonella to persist in pigs, the objective of this study was to develop an immunohistochemical approach for the detection of salmonellae in tissue of pigs experimentally infected with Salmonella Typhimurium. Samples were obtained from a challenge trial in which piglets of the German Landrace were intragastrically infected with Salmonella enterica serovar Typhimurium DT104 (1.4-2.1×1010 CFU). Piglets were sacrificed on days 2 and 28 post infection. Tissue samples of jejunum, ileum, colon, ileocecal mesenteric lymph nodes (Lnn. ileocolici), and tonsils (Tonsilla veli palatini) were fixed in Zamboni’s fixative and paraffin-embedded. Different immunohistochemical staining protocols were evaluated. Salmonella was detected in varying amounts in the tissues. Brown iron-containing pigments in the lymph nodes interfered with the identification of Salmonella if DAB was used as a staining reagent. Detergents like Triton X-100 or Saponin enhanced the sensitivity. It seems advisable not to use a detection system with brown staining for bacteria in an experimental setup involving intestinal damage including haemorrhage. The use of detergents appears to result in a higher sensitivity in the immunohistochemical detection of salmonellae.

In Vitro Spectral Analysis of Tattoo Pigments

BACKGROUND Absorption spectra of common tattoo pigments, their reaction to irradiation at 532 and 752 nm, and correlation with their titanium and iron component are important to the selection of an optimal laser device. OBJECTIVE The objectives were (1) to establish the absorption spectra of common tattoo pigments and India ink and (2) to determine their response to laser irradiation at 532 and 752 nm and correlate this to their composition. MATERIALS AND METHODS Samples of 28 tattoo pigments and India ink were mixed in agar and analyzed with a spectrophotometer. These agar plates were irradiated with Q-switched wavelengths of 532 and 752 nm. RESULTS The highest absorbance of red was in the complementary spectrum, while blue, yellow, and orange had peaks in the adjacent portion of the visible light spectrum. There is great variability in the absorbance of green tattoo material. Pigment darkening was noted at both wavelengths in all iron-containing pigments except black. It was variable in those containing titanium. Pigments tested responded with either clearance or darkening at 532 nm; however, response at 752 nm was more limited. CONCLUSION (1) Tattoo pigment absorption spectra can explain why some colors are more resistant to removal. (2) Pigment darkening is a complex process.

In Vitro Spectral Analysis of Tattoo Pigments

Absorption spectra of common tattoo pigments, their reaction to irradiation at 532 and 752 nm, and correlation with their titanium and iron component are important to the selection of an optimal laser device. The objectives were (1) to establish the absorption spectra of common tattoo pigments and India ink and (2) to determine their response to laser irradiation at 532 and 752 nm and correlate this to their composition. Samples of 28 tattoo pigments and India ink were mixed in agar and analyzed with a spectrophotometer. These agar plates were irradiated with Q-switched wavelengths of 532 and 752 nm. The highest absorbance of red was in the complementary spectrum, while blue, yellow, and orange had peaks in the adjacent portion of the visible light spectrum. There is great variability in the absorbance of green tattoo material. Pigment darkening was noted at both wavelengths in all iron-containing pigments except black. It was variable in those containing titanium. Pigments tested responded with either clearance or darkening at 532 nm; however, response at 752 nm was more limited. (1) Tattoo pigment absorption spectra can explain why some colors are more resistant to removal. (2) Pigment darkening is a complex process.

Influence of iron-containing pigments on the color of soils on alluvium of the Middle Kama plain

The study of the color in the CIE-L * a * b * system proved that, among the soils developed on the recent and ancient alluvium in the Perm Cis-Urals region, there are no soils composed of only brown horizons: the low-redness topsoils occur even in the automorphic soils. The color of the bulk of the soils does not depend on the total content of Fe-(hydr)oxide particles. The soils developed on the two-layered deposits are an exception, since the color of the lower layer of the heavy loam is affected by hematite-containing clay particles. In the upper horizons of other automorphic soils, red pigment is produced rather by Fe-containing hydroxides (feroxyhyte δFeOOH and Fe-vernadite Fe-δMnO2) than by hematite αFe2O3. The gleyed horizons are rich in free iron compounds (up to 3.2% (Fe2O3)d) that exert a weak effect on the redness. An identification procedure of the horizons showing hydromorphic features is developed, including the color control both in the untreated samples and in the samples in which the organic substance has been oxidized with H2O2. The soil becoming green after the organic matter oxidation appears to be a distinctive feature of the hydromorphic horizons, while reddening is a property of the automorphic horizons.

Safety Assessment of MIBK (Methyl Isobutyl Ketone)1

MIBK (Methyl Isobutyl Ketone) is an aliphatic ketone that functions as both a denaturant and solvent in cosmetic products. Current use in cosmetic products is very limited, but MIBK is reported to be used in one nail correction pen (volume = 3 ml) at a concentration of 21%. The maximum percutaneous absorption rate in guinea pigs is 1.1 micromol/min/cm2 at 10 to 45 min. Metabolites include 4-hydroxy-4-methyl-2-pentanone (oxidation product) and 4-methyl-2-pentanol (4-MPOL) (reduction product). Values for the serum half-life and total clearance time of MIBK in animals were 66 min and 6 h, respectively. In clinical tests, most of the absorbed MIBK had been eliminated from the body 90 min post exposure. MIBK was not toxic via the oral or dermal route of exposure in acute, short-term, or subchronic animal studies, except that nephrotoxicity was observed in rats dosed with 1 g/kg in a short-term study. MIBK was an ocular and skin irritant in animal tests. Ocular irritation was noted in 12 volunteers exposed to 200 ppm MIBK for 15 min in a clinical test. A depression of the vestibulo-oculomotor reflex was seen with intravenous infusion of MIBK (in an emulsion) at 30 microM/kg/min in female rats. The no-observed-effect level in rats exposed orally to MIBK was 50 mg/kg. Both gross and microscopic evidence of lung damage were reported in acute inhalation toxicity studies in animals. Short-term and subchronic inhalation exposures (as low as 100 ppm) produced effects in the kidney and liver that were species and sex dependent. Dermal doses of 300 or 600 mg/kg for 4 months in rats produced reduced mitotic activity in hair follicles, increased thickness of horny and granular cell layers of the epidermis, a decrease in the number of reactive centers in follicles (spleen), an increase in the number of iron-containing pigments in the area of the red pulp (spleen), and a reduction in the lipid content of the cortical layer of the adrenal glands. Neuropathological changes in the most distal portions of the tibial and ulnar nerves were observed in young adult rats which inhaled 1500 ppm MIBK for up to 5 months. No adverse effects were seen in any other neurological end point by any route of exposure in other studies using rats or other animal species. Clinical tests demonstrated a threshold for MIBK-induced irritation of the lungs at 0.03 to 0.1 mg/L after 1 min of respiration. MIBK was not mutagenic in the Ames test or in a mitotic gene-conversion assay in bacteria. Mammalian mutagenicity test results were also negative in the following assays: mouse lymphoma, unscheduled DNA synthesis, micronucleus, cell transformation, and chromosome damage. MIBK did not induce any treatment-related increases in embryotoxicity or fetal malformations in pregnant Fischer 344 rats or CD-1 mice that inhaled MIBK at concentrations of 300, 1000, or 3000 ppm. There was evidence of treatment-related maternal toxicity only at the highest concentration tested. MIBK applied to the tail of rats daily at doses of 300 or 600 mg/kg for 4 months produced changes in the testes, including a reduction in the number of spermatocytes, spermatids, and spermatozoa. An ongoing carcinogenicity study of MIBK being conducted by the National Toxicology Program will be considered when the results are available. On the basis of the information that is currently available, MIBK is considered safe as used in nail polish removers and as an alcohol denaturant in cosmetic products.

A Mössbauer approach to the physico-chemical characterization of iron-containing pigments for historical wall paintings

A series of commercially available iron-containing pigments (red or yellow ochre and green earths) has been primarily investigated by means of Mössbauer spectroscopy. The quantitative distribution of iron among various sites, and the iron(II) to iron(III) ratio were determined. FT-IR, SEM and EDX microscopy and XRD diffractometry have also been used for a more appropriate analytical identification and physico-chemical classification of the examined pigments. The pigments were divided into various groups according to their physico-chemical properties and compared with the data obtained on wall painting samples, prepared in the laboratory as reference, and on fragments from frescoes by Piero della Francesca (S. Francesco Church in Arezzo), G.F. Bembo, G. Romanino, R. Boccacino (Cathedral in Cremona) and G. Vasari and F. Zuccari (Cathedral in Florence). It was found that the commercially available samples, although synthetic, are not pure products and may contain additional compounds or additional iron derivatives.

Effect of iron compounds (oxide, salt, or complexes) on poly(vinyl chloride) thermal and photochemical stability

The color requirements for vinyl siding have drastically evolved over the last decade and have moved toward medium to dark colors. Therefore, manufacturers are exploring new ways to modify their formulations in order to improve weather-ability of these challenging colors. Examination of some of the PVC additives typically used in these formulations has led to some interesting revelations about the performance of iron-containing pigments, which are extensively used in darker colors. A quick weathering test was designed to evaluate the effect of iron in PVC formulations, and this test clearly demonstrates the correlation between iron content and PVC photodegradation.

On the possibility of the use of the Mössbauer test for bank-note forgeries and printer ink control

True and forged USA dollar bank-notes, as well as true German marks, are the object of Mössbauer spectroscopy and X-ray fluorescence investigation. Initial results on the iron-containing pigments in printer ink are presented. The pigments show Mössbauer spectra typical for nonstoichiometric Fe 3O 4, γ-Fe 2O 3 and α-Fe or more complicated phases. Additional information about the elemental composition of pigments is obtained from X-ray fluorescence analyses. Some of the pigments are traced with rare earth elements. The relatively high concentration of iron-containing pigments in the printer ink used and the specificity of their Mössbauer spectra indicate that Mössbauer spectroscopy may be a useful tool in law courts for the identification of fakes and forgeries, and can also be used in industry for printer ink control.

Superficial siderosis of the central nervous system: report of three cases and review of the literature

We present 3 cases and a review of the literature to demonstrate the current state of clinical diagnosis and therapy of superficial siderosis of the central nervous system. Typical symptoms were progressive cerebellar ataxia, spasticity and hearing loss. Repeated subarachnoid hemorrhage was indicated by persistent xanthochromia of the cerebrospinal fluid and confirmed by the presence of erythrophages, siderophages and iron-containing pigments. Deposition of free iron and hemosiderin in pial and subpial structures leads to intoxication of the central nervous system and represents the pathophysiological mechanism of superficial siderosis. Hypointensity of the marginal zones of the central nervous system on T2 weighted MR images indicates an iron-induced susceptibility effect and seems pathognomonic for superficial siderosis. In 39 of the 43 previously described cases superficial siderosis was verified by biopsy or autopsy. Today magnetic resonance imaging enables diagnosis at an early stage of the disease. Therapeutic management requires the elimination of any potential source of bleeding. In patients with unknown etiology no proofed therapy is yet available.

About some features of the course of hemochromatosis

Hemochromatosis is a hereditary disease characterized by a violation of the metabolism of iron-containing pigments. The body of an adult should contain about 4-5 g of iron. With hemochromatosis, the intensity of iron absorption increases significantly, as a result, its amount in the body increases, sometimes reaching 25-50 g. Excess iron is used to form hemosiderin, which is deposited in the skin and parenchymal organs

Staining of Iron

To the Editor.— Bark's query (231:25, 1975) about the failure of decalcified marrow to react with the Prussian blue stain for iron answered by Schmorl. 1 In the fixation for pigment identification, Schmorl warns against the use of acid fixatives if search for iron-containing pigments planned. Hence the recommendation for the use of many fixatives. Hemosiderin, for example, is soluble in acids, insoluble in alkalis and fat-dissolving media, not attacked by bleaches and not blackened either by osmic acid or silver nitrate.1(p183)

Synthesis of iron-containing willemite pigments

Synthesis of iron-containing willemite pigments

Aerobic metabolism of Streptococcus agalactiae.

Streptococcus agalactiae cultures possess an aerobic pathway for glucose oxidation that is strongly inhibited by cyanide. The products of glucose oxidation by aerobically grown cells of S. agalactiae 50 are lactic and acetic acids, acetylmethylcarbinol, and carbon dioxide. Glucose degradation products by aerobically grown cells, as percentage of glucose carbon, were 52 to 61% lactic acid, 20 to 23% acetic acid, 5.5 to 6.5% acetylmethylcarbinol, and 14 to 16% carbon dioxide. There was no evidence for a pentose cycle or a tricarboxylic acid cycle. Crude cell-free extracts of S. agalactiae 50 possessed a strong reduced nicotinamide adenine dinucleotide (NADH(2)) oxidase that is also cyanide-sensitive. Dialysis or ultrafiltration of the crude, cell-free extract resulted in loss of NADH(2) oxidase activity. Oxidase activity was restored to the inactive extract by addition of the ultrafiltrate or by addition of menadione or K(3)Fe(CN)(6). Noncytochrome iron-containing pigments were present in cell-free extracts of S. agalactiae. The possible participation of these pigments in the respiration of S. agalactiae is presently being studied.

A histochemical study of intranuclera inclusions in mouse liver and hepatoma.

Intranuclear inclusions which develop in the hepatic cells of mice fed a methionine-rich basal/bentonite diet and inclusions which occur spontaneously in a transplantable hepatoma contain materials of cytoplasmic origin which have become segregated within the nucleus. These materials include sudanophilic lipids, glycogen, iron-containing pigments, and the enzymes acid and alkaline phosphatase, non-specific esterase and β-glucuronidase. In general, their presence in the inclusions varies with their abundance in the cytoplasm. Mitochondria and the succinic dehydrogenase activity associated with them have not been observed within these intranuclear inclusions. Ihe inclusions are always enveloped by a layer of desoxyribonucleic acid which resembles that which lines the nuclear membrane. They arise contiguous to the nuclear membrane and appear to increase in size gradually. Hence, it is possible that the inclusions may represent invaginations of the nuclear membrane in which cytoplasmic materials accumulate. It is also postulated, however, that inclusions could be and may be formed by accumulation of cytoplasmic materials which normally diffuse freely between the swollen chromosomal vesicles of the resting nucleus. The inclusions arise under a great variety of conditions, but they invariably occur in greatly enlarged nuclei. The altered relationship of nuclear surface to nuclear volume may play an important role in the formation of intranuclear inclusions.

Azo dyes and Heinz bodies.

No general hypothesis has been advanced to explain the underlying cause of the appearance of Heinz bodies in erythrocytes. The initial observation of Riess (1882) on a case of potassium chlorate poisoning was followed by that of Heinz (1890) who administered phenylhydrazine to animals. Since then Heinz bodies have been induced by a great variety of substances, principally aromatic and aliphatic nitro-compounds, aromatic amines and organic (notably azo) dyestuffs, a miscellaneous group of organic nitrogen-free compounds (e.g., naphthalene, 2 :4 dichlorphenol, ascorbic acid), and a number of inorganic substances (e.g., sodium nitrite, sodium sulphite, potassium dichromate, arsine). Heinz bodies are also found normally in cats (Hecht and Wingler, 1952) and their appearance has been observed after splenectomy in animals (Schilling, 1921 ; Freifeld, Schiiowa, and Ludwinow sky, 1937) and in human subjects (Zadek and Burg, 1930; Selwyn, 1955). The substance of Heinz bodies has been thought by many to originate from haemoglobin rather than the cell stroma, and recently Beaven and White (1954) have demonstrated that it is spectroscopically similar to insoluble green haemoglobin which is described as being com plex, containing haems and other iron-containing pigments bound to denatured globin . Associated with the appearance of Heinz bodies, though not invariably, are anaemia, methaemoglobinaemia, and verdohaemoglobinaemia : these and other topics have been exhaustively reviewed by Fertman and Fertman (1955). The use of azo dyes for the colouring of food has led to some preoccupation regarding the possible carcinogenic and toxic effects of the dyes or of the products resulting from reduction-fission at the azo linkage. The current need for more information on dye toxicity is emphasized in the report on colouring matters issued by the Food Standards Committee of the Ministry of Food (1954) wherein reference is made to the work of Hecht and Wingler (1952). These authors point out that although fission products such as aniline, toluidine, or xylidine may not have been proved to be carcinogenic, their other known toxic properties rule out the use of the parent dye in food. A suitable dye might be assessed from this point of view by estimation of the degree of methaem oglobinaemia produced, but Hecht and Wingler (loc.cit.) advocate instead the examination of the blood for Heinz bodies, as this procedure is simpler and more sensitive. These authors reported that no Heinz bodies were produced by azo dyes of the type / 1St1St_t> (R = sulphonated aromatic \_/ ~ component) when the aniline component was sulphonated. This finding accords well with the generally accepted view that sulphonation has a detoxicating effect, and enhances the value of the Heinz body test as an indication of the presence of, for example, free amines. In a later paper, Wingler (1953) found that methylation at the para position on the aniline component of benzene-azo-naphthol 6 and 6 : 8 sulphonates likewise removes Heinz body-forming activity. In the work described in this paper the activity of eight azo dyes (Table 1) has been observed in order to compare the effect of substituent groups in the benzene-azo-naphthalene nucleus. The dyes were administered in the food since an ultimate object has been to assess the significance of Heinz body formation in the problem of food colours for human consumption.