Pigments Essay examples -- History, Prehistoric Painters

Pigments From prehistoric times, humans had discove inflamed that pigments could be use to colour a surface and they have left their mark on their environment in the form of painted images 7. Prehistoric painters employ the pigments in stock(predicate) in the vicinity of their homes. These pigments were the so-called earth pigments, soot from burning fleshly fat and charcoal from the fire. The colours available were yellow ochre, red ochre, and foreboding(a) 7, but with time, more colours were being discovered. In general, pigments are influence material which is insoluble in a medium where they are bodied 8. Pigments allow tend to absorb certain wavelength of light and reflect the others 9. Wavelength reflected will represent the colour of the pigment. Dyes are coloured material which will separate in the medium and lose their crystal or particulate construction during the attend 9.Pigments dirty dog be classified into synthetic pigments and indwelling pigments 8. The ex amples of natural 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 commencement ceremony chemically synthesised pigments were made in Germany in 1704 by Diesbach who manufactured red lake pigments using potash and alkali as substrate 7. Synthetic pigments can be divided into inorganic and organic pigments. Synthetic inorganic pigments ordinarily composed by metal oxide or compound which from by the armament of metal oxides. Moreover, the inorganic pigments possess thermal and chemical stabilities at blue temperature. Most of the inorganic pigments are derived from toxic meta... ...-degradable. The increase of the packaging wastes caused stern global environmental problem 36. Therefore, the development of perishable packaging materials from renewable natural resour ces has received widespread government support in EU countries and many national or international organisations 35.The term biodegradable materials is used to describe those materials which can be degraded by the enzymatic do of living 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 based 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.