Shellac bleached

Shellac, Bleached, occurs as an off white to tan, amorphous, granular resin. Shellac is obtained from lac, the resinous secretion of the insect Laccifer (Tachardia) lacca Kerr (Fam. Coc-cidae). Shellac, Bleached, is obtained by dissolving the lac in aqueous sodium carbonate, followed by bleaching with sodium hypochlorite, precipitation of the bleached lac with a dilute sulfuric acid solution, and drying. It is freely (though very slowly) soluble in alcohol, insoluble in water, and slightly soluble in acetone and in ether. Shellac, Bleached, is usually dissolved in a suitable solvent for application to food products. 

Identification Shellac, Bleached, Wax-Free, responds to the Identification Test in the monograph for Bleached Shellac. Acid Value Between 75 and 91. 

The PhEur 2005 defines four types of shellac depending on the nature of the treatment of the crude shellac (seed lac) wax-containing shellac bleached shellac dewaxed shellac and bleached dewaxed shellac. The USPNF 23 similarly defines four types of shellac orange shellac dewaxed orange shellac regular bleached (white) shellac and refined bleached shellac. The JP 2001 defines two types purified shellac and white shellac (bleached). 

Raw lac is first treated to remove water-soluble carbohydrates and the dye that gives lac its red color. Also removed are woody materials, insect bodies, and trash. It is further refined by either hot filtration or a solvent process. In the heat process, the dried, refined lac is filtered molten through cloth or wine screens to produce the standard grades of orange shellac. In the solvent process, lac is dissolved and refluxed in alcohol solvents, filtered to remove dirt and impurities, and concentrated by evaporation. The lac can be further decolori2ed in this process to produce very pale grades. Bleached shellac is prepared by treatment with dilute sodium hypochlorite and coalesced into slabs. 

White shellac is obtd by bleaching orn shellac with Na hypochlorite. Both are insol in w, but sol in ale. Their extensive list of uses includes paints, varnishes, dielectric compns, sealing wax and match heads (Ref 3, 768-L Ref 5, 1018-L)... 

SHELLAC. A secretion or excretion of the lac insect, Coccus lacca, found in the forests of Assam and Siam. Freed from wood it is called seed lac." It is soluble in alkaline solutions such as ammonia, sodium borate, sodium carbonate and sodium hydroxide, and also in various organic chemicals. When dissolved in acetone or alcohol, shellac yields the familiar shellac varnish of superior gloss and hardness. Orange shellac is bleached with sodium hypochlorite solution to form white shellac. See also Paints and Coatings. 

SYNS WHITE SHELLAC REGULAR BLEACHED SHELLAC... 

Glaessner, Austria, 1931), ammoniacal bleached shellac (Wruble, 1933), stearic acid, carnauba wax, petrolatum, elm bark, and agar (Miller, 1935, and Worton, 1938), and abietic, oleic, and benzoic acids with methyl abietate (Eldred, 1937). Since 1940, research on enteric coatings has focused on the synthesis of resinous polymers, which are insoluble in acids, such as cellulose acetate phthalate (Hiatt, 1940) and a glycerol-stearic acid-phthalic anhydride ester (Volweiler and Moore, 1940). 

Bleached shellac CertiSeal dewaxed orange shellac E904 lac Mantrolac R-49-, orange shellac refined bleached shellac regular bleached shellac Swanlac. 

Various different grades of modified or refined shellac are available, which may be broadly defined as either bleached or orange shellac. Orange shellac is essentially the crude shellac obtained from seed lac, as described above. It may retain most of its wax or be dewaxed, and may contain less of the natural color than was originally present. The quantities of wax, coloring material, and other impurities present may vary the... 

Bleached or white shellac is obtained by dissolving shellac in aqueous sodium carbonate, bleaching the solution with sodium hypochlorite, and precipitating the bleached shellac with 2 N sulfuric acid. Removal of wax by filtration results in a refined bleached shellac. 

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