Today, "handmade soap" has become a fashion. There are many strange sayings about the production of "handmade soap", such as "handmade soap should be left to mature", "the older the handmade soap is, the milder it will be, and it can last for a long time", "the cold-processed handmade soap has special effects"… these are all is that true?
Their Statement: Handmade soap should be kept for at least one month, Marseille soap or pure olive soap and other single oils should be kept for three months. Most people keep soap for three months; put pH test paper in the foaming soap On the surface, the pH of the newly made soap is around 11, and it is about 7 after maturity. Old soap is milder than new. However, soap should not be kept for more than three years.
The Fact
Soap is simply made by reacting sodium hydroxide with fatty acids in oils and fats to form sodium fatty acids. The fatty chain of fatty acid sodium is partially lipophilic, and the sodium salt is partially hydrophilic, which can disintegrate water-insoluble dirt.
Because handmade soaps are mostly cold-processed, the time required for saponification is greatly extended. Handmade soaps that are not fully cured contain unreacted strong alkalis, which can damage the skin. "The long time, the alkaline will become smaller" is not very accurate. During the aging process, the sodium hydroxide gradually decreases, and the alkalinity gradually decreases, but after the saponification is complete, the alkalinity will not change for a long time, and the pH value is between 8-9, not 7. This It is determined by the alkalinity of sodium fatty acid.
However, soaps made from vegetable oils have problems with oxidation. The fatty acids in olive oil are mostly monounsaturated fatty acids. Unsaturated fatty acids deteriorate due to oxidation. The same is true for the fatty chain portion of the sodium fatty acid after it is made into soap. After a long time, on the one hand, the cleaning effect will be poor, and on the other hand, short-chain aldehydes will be obtained, which are toxic to a certain extent. Storage conditions can affect the rate of oxidation. In general, wrapping carefully (reduces contact with air), protecting from light, and storing in the refrigerator (low temperature) can prolong the shelf life. However, because deterioration is an ongoing process, it is still recommended to use it as soon as possible after the aging is complete.
Extended description
For people who like to do handicrafts, making handmade soaps can be fun, but if you want handmade soaps to have "better results", it's a bit impractical.
Many people use olive oil to make handmade soaps, hoping for some benefit. In fact, this is also the "selling point" of cold castile soap, on the grounds that "at a temperature of around 50°C, the active ingredients in olive oil will not be destroyed." The unsaturated fatty acids in olive oil may have some benefits, but after being made into soap and used, they are eventually washed away by water and cannot be absorbed. Other ingredients in olive oil, such as vitamins and minerals, are unlikely to have any noticeable effect because they stay on the skin for a limited amount of time. It is worth mentioning that handmade soaps lack strict inspection. If the ingredients are wrong or the aging time is not long enough, it may cause damage to the skin.
Conclusion
Partially true.
