Do you know how "dirt" such as sweat and excess oil are removed from our skin?
This is because of a compound called surfactant or also known as surface-active agent. This compound makes water and oil mix together. Surfactants are made by combining natural ingredients such as lecithin, which is found in soy saponin and egg yolks, and caustic soda (sodium hydroxide) or caustic potash (potassium hydroxide). Petroleum also contains surfactants. Detergent is created by mixing natural soap and surfactants together.
Soap is divided into two major types: sodium soap (solid soap) and potassium soap (gel or liquid soap).
Sodium soap (solid soap) is made of a compound called "sodium fatty acid (fatty acid Na)". Sodium fatty acid is formed by combining vegetable or animal fats with sodium hydroxide (caustic soda) and causes both substances to undergo chemical reaction.
On the other hand, potassium soap (gel or liquid soap) is made of a compound called "potassium fatty acid (fatty acid K)". Potassium fatty acid is formed by similarly combining vegetable or animal fats with potassium hydroxide (caustic potash) and causes both substances to undergo chemical reaction.
Fatty acid K is a highly soluble gel and it easily dissolves into liquid when poured with water.
Fatty acid Na and fatty acid K are both called "base soaps". Whether the base soap is liquid or solid form, it is still "soap". Our green papaya soap is a solid type, so it is technically sodium soap.
When people hear the words like "sodium hydroxide" or "potassium fatty acid", some of them may probably think that our soap is entirely made of chemical substances instead of natural ingredients. The chemical substances mentioned here are one of the few things that are safe for our skin, though they are treated as if they are harmful to our body.
Besides, soap itself cannot be made without chemical reaction. This is also true for natto, yogurt, bread, wine and alcohol that cannot be created if chemical reaction by yeast does not take place.
Surfactants may affect our body, so let's be careful on using petroleum-based soaps.
The characteristics of natural soaps
1) Natural soap contains "glycerin", a substance isolated from fatty acids as a by-product of mixture and chemical reaction between fatty acids and sodium hydroxide or potassium hydroxide. The absence of additives such as stabilizers in natural soap explains why it melts easily. Nevertheless, it can still provide moisturizing effects to your skin.
The soap generates fatty acid ions when submerged in water. These ions instantly become insoluble once in contact with water and they absorb keratin from the surface of your skin. Moreover, even if you wash away these ions with water, they still stick on your skin, thus providing your skin moisturizing effects.
2) Natural soap has very effective moisturizing properties because it is rich in glycerin, a substance isolated from fatty acids and sticks on your skin. Because of this, natural soap is indeed gentle to skin and it can be used for babies who have delicate skin or by those who have sensitive or dry skin.
The characteristics of synthetic soap
1) Synthetic soap may have high cleansing properties, but it also causes skin irritation compared to natural soap.
2) Synthetic soap causes our skin to become dry because it has high degreasing powers and it removes sebum that serves as a natural barrier for our skin.
3) While substances from synthetic soap destroy our natural skin barrier, they even permeate through the hypodermis and cause damage to proteins.
4) Synthetic soap causes dry skin because it eliminates moisture from our skin or hair.
5) It would take long time for the bacteria to dissolve substances on our skin. Synthetic soap worsens the environment for them because they cannot dissolve substances it left behind.
6) Most petroleum-based synthetic soaps contain substances called surface-active agents. These substances are very effective in removing dirt from our skin, but they also destroy our natural skin barriers. There are several cases wherein additives such as moisturizing agents are often added to synthetic soaps in order to preserve skin moisture. Even if moisturizing agents are made of natural ingredients, this would lead to the important question why surface-active agents have to be added to the soap in the first place?