PIGMENT FAMILIES

2019

We discuss here materials used in the fabrication of works of art and handicrafts, among them pigments and dyes, gemstones and jewels. Attention is paid to their natural or synthetic origin and possible treatments. Methods of characterization are important not only for historical and restoration purposes and the reproduction of ancient processes, but also for the purposes of new productions. In particular, in the fields of the Effective Microorganisms and metal surfaces coloration, some goals have been reached in this direction due to convergence of different education and research experience of the authors.

Spectrochimica Acta Part A-molecular and Biomolecular Spectroscopy, 1998

The present study was undertaken to investigate the potential of spectrophotometric and fluorimetric techniques for identifying the materials used in artistic paintings. Two classes of organic colorants were examined, anthraquinoid and indigoid dyes, in their naturally occurring and synthetic forms. Absorption and fluorescence spectra were recorded in both solution and solid layer using linseed oil as a binder. Fluorescence quantum yields were determined. A non-destructive, instrumental set-up to record fluorescence spectra on painted surfaces was successfully tested. The solvent effects on the spectra of the dyes are interpreted in terms of intra-and inter-molecular hydrogen-bonding interactions. Molecular aggregation of indigo was investigated in dichloroethane solution and assigned to a dimer. The spectra recorded from the painted surfaces are broader than in solution. However, the emission spectra are still suitable to identify the colorants.

Pigments Pigments A pigment is a material like metal oxides, azo-dye etc. that changes the colour of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light. It must be stable in solid form at ambient temperatures. Q: Give one example of each white, black, green, purple, blue and red pigment. Purple pigments Cobalt Violet: Cobaltous orthophosphate. Manganese violet: NH 4 MnP 2 O 7 Manganic ammonium pyrophosphate Blue pigment Ultramarine: pigment of sulfur-containing sodio-silicate (Na 8-10 Al 6 Si 6 O 24 S 2-4) Cobalt Blue: cobalt(II) stannate Prussian Blue: a synthetic pigment of ferric hexacyanoferrate (Fe 7 (CN) 18). Green pigment Chrome green : chromic oxide (Cr 2 O 3) Paris Green: cupric acetoarsenite (Cu(C 2 H 3 O 2) 2 •3Cu(AsO 2) 2) Yellow pigment Cadmium Yellow: cadmium sulfide (CdS) Chrome Yellow: natural pigment of plumbous chromate (PbCrO 4). Mosaic gold: stannic sulfide (SnS 2) Orange pigment Chrome Orange: a naturally occurring pigment (PbCrO 4 + PbO) Red pigments Red Ochre: anhydrous Fe 2 O 3 Red Lead: lead tetroxide, Pb 3 O 4 Vermilion: Occurs naturally in mineral cinnabar. Mercuric sulfide (HgS) Black pigments Carbon Black Lamp Black White pigment Titanium White: titanic oxide (TiO 2

Natural product research, 2004

Today, natural colourants are emerging globally, leaving synthetic colourants behind in the race, due to the realisation that are safer and ecofriendly in nature. In this context, a brief review of natural colourant sources, their classification, chemical constituents responsible for producing different colours, its activities and effect of different mordants on the hue is discussed.

Gold Bulletin, 1999

From ancient times, gold has been used mostly in decorative items, and the colour of gold plays an important role in this application field. Different methods have been developed to objectively characterize the colour. This paper describes the CIELAB system, which has gained acceptance as an effective way to assess colour. The different coloured gold alloys known today are also described, with emphasis on the relationship between their metallurgy and their colour.

Journal of Chemical Education, 1980

ABSTRACT Properties and classification of artists' pigments, and procedures for the preparation of chrome yellow, Prussian blue, and thalo blue. Keywords (Audience): Second-Year Undergraduate

We present terahertz spectroscopy and analysis of two commercially available quinacridone pigments in the 0.5-4.5 THz range. Our results show a clear distinction between quinacridone red and magenta pigments. We reveal four definite absorptions in the terahertz regime common to both pigments, but offset between the pigments by ∼ 0.2 THz. The lowest-energy line in each pigment is observed to increase in frequency by ∼ 0.1 THz as the temperature is reduced from 300 to 12 K.

Chemistry and Artists' Colors Part III. Preparation and properties of artists ' pigments Artists' pigments may be prepared in many ways depending upon the nature of the starting material and the desired product. Naturally occurring minerals such as cinnabar or azurite are prepared by simply grinding the material until the desired particle size is reached. Others, such as chrome yellow, are prepared by precipitation of the insoluble pigments by interaction of aqueous solutions of soluble salts. Still others, like lead white and verdigris, are formed by the corrosion of lead and copper, respectively, by fumes of acetic acid. Ultramarine blue and chromium oxide green are examples of pigments which are pyrogenetic in origin, i.e., formed by the calcination of the starting materials in a furnace. Other pyrogenetic pigments of historical interest are Egyptian blue and smalt. Synthetic vermillion, zinc white and lampblack are examples of pigments prepared by forming fumes, or by combustion or sublimation. Organic pigments are prepared by the normal routes of organic synthesis, and purified by washing or recrystallization, when possible. The following syntheses may be carried out easily in a modestly equipped laboratory or demonstration table: 1) Preparation of Chrome Yellow. Chrome yellow (PbCr04) may be prepared easily by precipitating equimolar quantities of Pb2+ and Cr042-ions from aqueous solutions of their soluble salts. A typical equation is: Pb(N03)2(aq) + Na2Cr04(aq)-PbCr04(s) + 2NaN03(aq) Practical working quantities are 3.0 g of Pb(N03)2 and 1.5 g of Na2Cr04, each dissolved in 25 ml of water. The precipitated product may be filtered with suction, washed with water, and air-dried. 2) Preparation of Prussian Blue. Prussian Blue is just one of the many names by which this mixed-valence compound of iron is known. Other names for these so-called "iron blues" are potash blue, Chinese blue, French blue, and Milori blue; they are, however, most accurately

We can think of the simple structure in terms of what it is not rather than what it is.

Creiem que els Arxius Nobiliaris són l'expressió de la història i la memòria d'un o varis llinatges. A través dels documents escrits en pergamí o paper, però també a través dels signes-escuts, segells, signatures, filigranes, marques-elements tots ells identitaris.