Castille soap seems to be a generic name for any soap made of vegetable rather than animal fats.
The basic ingredients are vegetable oil, water and lye. So again it would seem to come down to looking at these ingredients. For example, I live in the main olive oil producing area in Europe, so I could quite easily obtain a castille soap made with local olive oil, water and lye. However many castille soaps will be made with palm or coconut oil.
And another thing, lye....
It´s another name for caustic soda (sodium hydroxide), a rough form of which is traditionally made from wood ash. However it is more commercially produced these days...
From wikipedia...
Methods of production
Sodium hydroxide is produced (along with chlorine and hydrogen) via the chloralkali process. This involves the electrolysis of an aqueous solution of sodium chloride. The sodium hydroxide builds up at the cathode, where water is reduced to hydrogen gas and hydroxide ion:
2Na+ + 2H2O + 2e− → H2 + 2NaOH
To produce NaOH it is necessary to prevent reaction of the NaOH with the chlorine. This is typically done in one of three ways, of which the membrane cell process is economically the most viable.
Mercury cell process (also called the Castner-Kellner process) – sodium metal forms as an amalgam at a mercury cathode; this sodium is then reacted with water to produce NaOH. There have been concerns about mercury releases, although modern plants claim to be safe in this regard. [1]
Diaphragm cell process – uses a steel cathode, and reaction of NaOH with Cl2 is prevented using a porous diaphragm. In the diaphragm cell process the anode area is separated from the cathode area by a permeable diaphragm. The brine is introduced into the anode compartment and flows through the diaphragm into the cathode compartment. A diluted caustic brine leaves the cell. The caustic soda must usually be concentrated to 50% and the salt removed. This is done using an evaporative process with about three tonnes of steam per tonne of caustic soda. The salt separated from the caustic brine can be used to saturate diluted brine. The chlorine contains oxygen and must often be purified by liquefaction and evaporation. [2] [3]
Membrane cell process – similar to the diaphragm cell process, with a Nafion membrane to separate the cathode and anode reactions. Only sodium ions and a little water pass through the membrane. It produces a higher quality of NaOH. Of the three processes, the membrane cell process requires the lowest consumption of electric energy and the amount of steam needed for concentration of the caustic is relatively small (less than one tonne per tonne of caustic soda). [4] [5]
An older method for sodium hydroxide production was the LeBlanc process, which produced sodium carbonate, followed by roasting to create carbon dioxide and sodium oxide. This method is still occasionally used. It helped to establish sodium hydroxide as an important commodity chemical.
Major producers
In the United States, the major producer of sodium hydroxide is the Dow Chemical Company, which has annual production around 3.7 million tonnes from sites at Freeport, Texas, and Plaquemine, Louisiana. Other major US producers include Oxychem, PPG, Olin, Pioneer Companies, Inc. (PIONA), and Formosa. All of these companies use the chloralkali process[6].
This seems to be throwing up more questions than answers doesn´t it.
Clara x.
