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Machine Made Shellac
Machine Made Shellac is produced in two different ways-Heat process and Solvent process.
Heat Process
Separation of pure lac is achieved by melting seedlac by steam heat and squeezing the soft molten lac through filter by means of hydraulic presses. The molten lac is then stretched by means of rollers into long and continuous sheets which is broken into pieces to form small flakes.
Grades of heat process Shellac (Machine made)
Solvent Process
The separation of insoluble impurities is achieved by dissolving the lac in a suitable solvent, usually industrial alcohol. The solution is then filtered through fine cloth and the alcohol is recovered by boiling the solution. The shellac is then stretched to the required thickness on a roller. The solvent process lends itself to manufacture different types of shellac containing varying percentage of shellac wax. Dewaxed or partly Dewaxed shellac may be manufactured by this process. The wax content may be as low as 0.2%.
Grades of Dewaxed Shellac
Bleached Shellac
The basic procedure in the production of bleached shellac consists of dissolving seedlac in aqueous sodium carbonate solution at 90-100 degree celcius. This solution is then treated with sodium hydrochloride, cooled and filtered. The bleached shellac is reclaimed from the filtered solution with sulphuric acid. The precipitated bleached shellac is then filtered and washed with water for removal of acid and dried.
Bleached shellac is manufactured / exported in following two grades :
Aleuritic Acid
Aleuritic Acid (9, 10, 16-trihydroxypalmitic acid), obtained from shellac by saponification, is a unique acid containing three hydroxyl groups of which two are of adjacent carbon atoms.
Aleuritic Acid is moderately soluble in hot water and crystallises out on cooling the solution. It is soluble in the lower alcohols such as methyl, ethyl and isopropyl alcohols.
Techinal grade Aleuritic Acid (purity 99%) a slight yellow and almost odourless solid, is now manufactured by us. There is a continuous growing demand of aleuritic acid in the fields of perfumery and pharmaceuticals due to it being an excellent starting material for the synthesis of civetone, ambrettolide, isoambrettolide etc, which have the musk like odour......Click here for the technical details
Shellac Wax
4-6 % of the wax is only contained in crude
Shellac and it is obtained as waste product
during the manufacturing of solvent process
of shellac.
The commercial qualities are hard, brown and
have excellent shine-producing
charac-teristics which can nearly be
compared with those of Carnauba Wax.
Shellac Wax is mainly a mixture of esters
(approx. 60 %) and free alcohol (approx. 35
%). Furthermore, small amounts of
hydrocarbons, penta- and hentriacontanes and
approx. 1 % laccic acid are contained.
Polishes which normally consist only of
paraffin and montan wax, give a highly
shining surface if only a small amount of
Shellac Wax is added; moreover as substitute
for Candelilla Wax.......Click here for the technical details
Storage
The Shellac produced is normally allowed to cool off after stretching for a few hours and then transferred to a cool-shedded godown. It is best stored in air-conditioned ware-houses which maintains a temperature between 14-18 degree centigrade. Storage under such conditions maintains the quality of Lac although its main function is to prevent Shellac from blocking in the hot weather which is encountered for most of the year in India. |
