Pigments Essay examples -- History, Prehistoric Painters

Pigments From prehistoric times, humans had discovered that pigments could be used to coloration a surface and they have left their mark on their environment in the form of painted images 7. Prehistoric painters used the pigments available in the vicinity of their homes. These pigments were the so-called earth pigments, soot from burning animal avoirdupois and charcoal from the fire. The colours available were yellow ochre, red ochre, and black 7, only when with time, more colours were being discovered. In general, pigments are coloured worldly which is insoluble in a medium where they are incorporated 8. Pigments testament tend to absorb certain wavelength of light and reflect the others 9. Wavelength reflected will exemplify the colour of the pigment. Dyes are coloured material which will dissolve in the medium and lose their crystal or particulate structure during the parade 9.Pigments can be classified into synthetic pigments and rude(a) pigments 8. The examples of natur al pigments founded in animals and vegetables are carotenoids, chlorophyll, melanins, flavins, quinones, and anthocyanins 5, 6, 10. In the industry, pigments are widely used as colouring agents in dyeing of cottons, silks and wool sample 11.2.1.1Synthetic PigmentsThe first chemically synthesised pigments were made in Ger numerous in 1704 by Diesbach who manufactured red lake pigments utilise potash and alkali as substrate 7. Synthetic pigments can be divided into inorganic and organic pigments. Synthetic inorganic pigments usually peaceful by metallic element oxide or compound which from by the host of metal oxides. Moreover, the inorganic pigments possess thermal and chemical stabilities at high temperature. approximately of the inorganic pigments are derived from toxic meta... ...-degradable. The increase of the packaging wastes caused serious orbicular environmental problem 36. Therefore, the development of biodegradable packaging materials from renewable natural resources has received widespread government support in EU countries and many national or international organisations 35.The term biodegradable materials is used to signalize those materials which can be degraded by the enzymatic action of life-time organisms, such as bacteria, yeasts, fungi and the ultimate end-products of the degradation process 37. biodegradable packaging materials may be broadly classified into biodegradable polymers and biopolymers ground on whether the dominating ingredient is synthetic oil-based polymer or a biologically derived polymer. Biopolymers are naturally occurring long-chain molecules such as cellulose, polysaccharides, proteins and DNA 35.