18 сентября, 2015 
Pokraskin Natural pearl essence is isolated as a silky lustrous suspension from fish scales. The pigment particles in the suspension are platelet shaped with a very high aspect ratio (0.05 pm x 1-10 pm x 20-50 pm), and consist of 75-97% guanine and 3-25% hypoxanthine [4, 6-8].
To date there is no commercial synthetic process for producing similar plateletshaped products of such brilliance. One is therefore limited to a process based on the natural supply. An aqueous suspension of white fish scales is treated with organic solvents in a complicated washing and phase-transfer process to remove proteins and irregular guanine crystals. One ton of fish yields less than 250 g of guanine. The pigment particles show a high tendency to agglomerate and are, therefore, only handled as dispersions.
Natural pearl essence is very expensive but shows some advantages over synthetic pearlescent pigments. For example, it shows a high but soft luster (nD = 1.79 (parallel) to 1.91 (perpendicular)), It is not brittle and has a relatively low density of 1.6 g/cm3, which reduces settling in liquid formulations. It is almost exclusively used in expensive cosmetic applications.
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