How is Castor Oil Extracted?
The oil is obtained from the seeds by two principal methods - expression and decoction.
The oil exported from Calcutta to Europe is prepared by shelling and crushing the seed between rollers. The crushed mass is then placed in hempen cloths and pressed in a screw or hydraulic press. The oil which exudes is mixed with water and heated till the water boils and the mucilaginous matter in the oil separates as a scum. It is next strained, then bleached in the sunlight and stored for exportation. .
There are two modes of extracting the oil by expression: (1) without heat, when it is termed 'cold drawn Castor Oil,' this process being largely carried out in Italy, Marseilles, Belgium, Hull and London; (2) with heat, the process generally adopted in America.
In the north of Italy, the fresh seeds are alone used, and after they have been crushed and the seed coats very carefully removed with a winnowing machine and by hand, the blanched seeds are put into small hempen bags, which are arranged in superposed layers in a powerful hydraulic press, with a sheet of iron heated to 90 degrees F. between each layer, so as to enable the oil to flow readily, they are finally submitted to pressure in a room, which in the winter is heated to a temperature of about 70 degrees. The oil which first flows is of the finest quality, but an inferior oil is subsequently obtained by pressing the mass at a somewhat higher temperature. The peeled seeds yield about 40 per cent. of oil. After expression, the oil is usually bleached by exposure to sunlight or by chemical means.
In America, where the oil is obtained by expression with heat,. There the seeds are submitted to a dry heat in a furnace for an hour or so, by which they are softened and prepared to part easily with their oil. They are then pressed in a large powerful screwpress, and the oily matter which flows out is mixed with an equal proportion of water, and boiled to purify it from mucilaginous and albuminous matter. After boiling about an hour, it is allowed to cool, the water is drawn off and the oil is transferred to zinc tanks or clarifiers capable of holding from 60 to 100 gallons. In these it stands about eight hours, bleaching in the sun, after which it is ready for storing. By this method, 100 lb. of good seeds yield about five gallons of pure oil.
http://www.botanical.com/botanical/mgmh/c/casoil32.html
I have heard that Turkey Red Oil is Castor Oil, is it?
Turkey Red Oil is produced by castor oil reacting with sulfuric acid. It is a surfactant and therefore makes a wonderful base for a bath oil as it mixes well with water, producing a milk bath. Apart from cosmetic uses, turkey red oil is used in fabric dyeing and as a preservative for leather because it blends with water and helps to keep leather that is stored under hot, dry, low humidity conditions soft and pliable.
http://www.wellnaturally.ca/carrier_oils/turkeyred.html
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