The soap should be neutral and should not be greasy or smell. The soap should be hard but not mushy , not brittle and once dried to retain its shape . The soap must be foaming : shaking 3 g of soap in 10 ml of water in a test tube for 10 seconds to form a layer of foam 2 cm high and persistent for at least 5 seconds .
Sodium salts of long chain carboxylic acids are not the only existing compounds used as soap . There are also so-called acid soaps - soaps for skin hypersensitive to normal - which consist of mixtures of surfactant alkyl sulfonic or organic esters of sulfuric acid. These soaps have a pH of 5.5, similar to the skin, therefore are less aggressive towards it.
The traditional soap is made from sodium salts of long chain carboxylic acids , the liquid soap dispenser appeared with the spread of plastic materials in the postwar period . The traditional soap is made from beef tallow (80 % ) and coconut oil or olive oil ( 20%) . Soap should be in the top positions among its ingredients, fatty acids saponified coconut , palm and olive oil.
Mills than once and some current production was produced with the pomace , or the pressing of olives that remained in the mill the mill after the first pressing (which gives extra virgin olive oil ) . Often they are second -or third- pomace oil of poor quality , which the law prohibits the marketing as cooking oil. After the war the second and third squeezing oil , less valuable and expensive, yet they were also used for food.
Various industrial mills use to produce soap residue and compensate for the low yield of olives harvested in terms of cooking oil , sometimes you get to grind the olives just to make soaps because most profitable oil bottle (30 % yield olives olive oil at 10 euros / liter vs. 100 % of the residue from which we get a similar amount of soap , without waste , sold at a price of EUR 1.5-2 per pound of soap ) .
In the late nineties Europeans discovered and began to import from India the fruit of a plant (a kind of nut ) used and distributed commercially as soap organic and non- polluting. These nuts are sold in blister herbal medicine and should be added , according to the dosage indicated in the clothes washing machine and have the same function as very common liquid and powder detergents are highly polluting . These nuts can also be used as a wash and there are so many different flavors (lavender , lemon, orange blossom , etc. ) . These plants are grown mainly in greenhouses in Germany and begin to produce nuts soap only after about three years old.
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