Soaps can be easily distinguished by their shape: bar, bar, cream or liquid.
There are also other factors to classify them, such as their ingredients, manufacturing methods or uses. Here we tell you more about each of them:
History of soap
Although the oldest known soap remains date from 2800 to. C. and were found in the area of Babylon, researchers do not know what is its origin and how it was invented.
The most widespread theories indicate that its appearance could be due to the ceremonial sacrifices of animals.
The rains could have washed the remains of fat and ash into nearby rivers, the inhabitants appreciating the foam that was formed and its ability to clean clothing or skin.
Currently, soap is made by mixing different oils, of vegetable origin (such as cotton, coconut , flax, corn, olive or soy), or of animal origin (using its fat, especially that of fish), with water and sodium hydroxide or potassium hydroxide (commonly called caustic soda).
Then essential oils of vegetable origin are added to give it aroma, and dyes for color.
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They are generally classified by their ingredients, the method to prepare them, or the use for which they are intended. Here we detail them:
Ingredients
Soaps can be differentiated by the material used to make them. This distinction can be made, first of all, by the use of animal fats or vegetable oils.
For example, there are milk soaps, which are used to care for the skin due to their softening and moisturizing properties.
Another category is that of flavored ones, standing out for the herbal extracts used to prepare them.
The most common are those of tea tree, lemon or lavender, although we can also find others that combine fragrance with the freshness of plants, such as algae or mint.
Stronger odors can be used in the preparation to use them in practices such as aromatherapy.
Manufacturing method
The technique used to make a soap will determine its characteristics. Once the mixture is prepared, you can choose between two pressing methods, one cold and one hot.
In cold pressing, the heat generated by the chemical reaction of fatty acids is used to produce soap.
As no heat is applied after having mixed the ingredients, the properties of the oils used are not altered and processing is faster.
However, once it has cooled, it takes a longer amount of time to complete the saponification process (conversion of oils or fatty compounds into soap).
It is estimated a wait of approximately one month to be able to use it.
Hot pressing consists of a slower process, in which the oils or compounds are cooked fatty until reaching a gelling state.
This allows to complete the saponification more quickly, so it is not necessary, as in the previous case, to wait to use it once it has cooled.
Uses
In this case you can differentiate those soaps used for personal hygiene from those used for general cleaning.
Some contain a greater amount of total fatty material, so they are used throughout the body for their moisturizing effect, while others are specific for the face.
Another ideal option to moisturize are those made with glycerin, which allow the skin to look fresh and smooth for longer.
There are also medicinal soaps, that is, specifically prepared to treat different skin conditions: acne , rashes, pimples, bacterial infections or fungal .
Finally, we can find those that are used for cleaning dishes or clothes, with a greater capacity to produce foam.
There are even soaps that are used to clean heavy dirt, such as grease or oil stains.
How soap works
Broadly speaking, the cleaning action of soap is due to the fact that, on the one hand, it can dissolve in water (it is water soluble).
This reduces the surface tension of the water, which favors its penetration into the interstices of the substance to be washed.
On the other hand, it is capable of dissolving in fat (it is fat soluble), affecting its structure and allowing it to be diluted in water.
Sources consulted : Exhaustive Database of Natural Medicines, Centers for Control and Disease Prevention, National Institute of Complementary and Alternative Medicine.