What is soap?
It does not have a standard definition. Generally, soap can be understood as fatty acid salts obtained by the reaction of long-chain fatty acids and alkalis. Soap-based cleansing products refer to cleansing products with fatty acid salts as the core component.
Soap is a salt obtained after the reaction of fatty acid and alkali. The commonly used alkali is potassium hydroxide, and sodium hydroxide or triethanolamine are also used in some products. And yet, the salt generated by sodium hydroxide is too hard and is only suitable for solid soap.
At the same time, the salt generated by triethanolamine is too soft. It easily changes color when encountering iron ions, so it is very convenient to judge by grasping the characteristic of potassium hydroxide.
Pros and Cons
- The soap-based formula has the advantages of strong cleaning power, rich foam, and a refreshing skin feels, so people with oily skin love to use it.
- The disadvantage of the soap-based formula is that the cleaning power is too strong, which can easily cause excessive cleaning, such as more oily after washing, oily outside and dry inside, skin sensitivity, and so on.
Soap-based cleansing products are cheap and easy to use, and they are still mainstream in the market, but they should be used scientifically. They are suitable for healthy oily skin in the evening in summer; they can be used for weekly care in spring, autumn, and winter, and once a week is enough. Normal and dry skin should be used sparingly; sensitive skin should be kept at a respectful distance.
How to judge whether a facial cleanser is a soap-based formula?
Two judgment rules are given below.
Rule #1: If potassium hydroxide is listed in the ingredient list, you can be 80% confident that it is a soap-based formula.
Rule #2: If Potassium Hydroxide is in the top 7 ingredients, you are 99% sure it is a soap-based formula.
Why is Potassium Hydroxide in the top 7 of the ingredient list?
Because commonly used fatty acids include lauric acid, myristic acid, palmitic acid, and stearic acid. According to the different requirements of the product, one kind of acid is generally used as the main body, and other acids are used as auxiliary combinations. Sometimes only 3 or 2 kinds of fatty acids may be used, and sometimes all 4 are used.
Considering the most extreme case, 4 fatty acids will be used, plus water and moisturizing alcohol. Then it is the turn of potassium hydroxide, so the ranking of potassium hydroxide should be in the top 7.
Soap base composition analysis of different products
- Taking facial cleanser A as an example to analyze the characteristics of the soap base formula, its ingredients are as follows:
Water, Myristic Acid, Glycerin, Behenic Acid, Palmitic Acid, Potassium Hydroxide, Sodium Methyl Cocoyl Taurate, Lauric Acid, Stearic Acid, Montmorillonite, Fragrance, PEG-3 Distearate , Disodium EDTA, Sodium PCA, Urea, BHT, Caffeine, Saw Palmetto Fruit Extract, Polyquaternium-7, Phenoxyethanol, Sodium Hyaluronate, Magnesium Nitrate, Yeast Lysate Extract , Trehalose, Polyquaternium-51, Butylene Glycol, Dipotassium Glycyrrhizinate, Yeast Extract, Pomegranate Juice, Tocopheryl Acetate, Creatine, Methylchloroisothiazolinone, Lycium Chinense Fruit extract, magnesium chloride, etc.
The ingredient list contains myristic acid, palmitic acid, potassium hydroxide, lauric acid, and stearic acid, and potassium hydroxide ranks sixth in a typical soap-based formula.
The antiseptic system in this ingredient list is polyquaternium salt, butylated hydroxytoluene, Phenoxyethanol, and Cathone (a mixture of magnesium chloride and nitrate) methylisothiazolinone, and methylchloroisothiazolinone), and the antiseptic effect is very good. Good, but it irritates the skin and can only be used in rinse-off cosmetics. Although it is reasonable and legal for high-end brands to use this preservative, it does not match the brand image.
Sodium hyaluronate and many extracts are added to the ingredient list as moisturizing and anti-aging ingredients. However, after phenoxyethanol, the amount added must be very small, and the facial cleanser stays on the face for a long time. Both are very short, wash off quickly, and have no way of functioning.
The fragrance ranks high in the typical department store brand practice ingredient list. Some people like it, and some don’t.
Although the brand and advertisement are high-end, the raw materials and formula are not commendable. Many unnecessary flavors and pigments are added, a typical practice of big brands putting the cart before the horse.
- Another example is B cleanser. Its ingredients are as follows:
Water, Stearic Acid, Macrogol-8, Myristic Acid, Potassium Hydroxide, Glycerin, Lauric Acid, Ethanol, Butylene Glycol, Glyceryl Stearate SE, Polyquaternium-7, Phytosterol/Caprylyl Cyldodecyl Lauroyl Glutamate, Sericin, Disodium EDTA, Potassium Sorbate, etc.
Potassium hydroxide ranks relatively high in the ingredient list and has strong cleaning power. By adding hygroscopic agents such as polyethylene glycol and glycerin and oily ingredients to reduce dryness after cleansing, the face will not feel tight after washing. Still, the essence of the product remains the same. Long-term use will aggravate skin dryness and sensitivity.
Based on the previous two rules, if you see the words deep, thorough, strong, refreshing, and oil control in the name, then you can be 100% sure that this is a soap-based formula based on the product name and advertising claims. Reasonable inferences.
- For example, C facial cleanser has the following ingredients:
Water, Glycerin, Myristic Acid, Propylene Glycol, Palmitic Acid, Stearic Acid, Potassium Hydroxide, Lauric Acid, Macrogol-8, Glyceryl Stearate, PEG-150 Distearate, Crinkled Carrageenan Vegetable extract, hydroxyethyl cellulose, essence, etc.
- Another example is D facial cleanser. Its ingredients are as follows:
Water, Stearic Acid, Glycerin, Macrogol-8, Propylene Glycol, Myristic Acid, Potassium Hydroxide, Lauric Acid, Beeswax, Glyceryl Stearate, etc.
The above two products are very typical soap-based cleansing products.
- Another example is an E facial cleanser. Its ingredients are as follows:
Water, Stearic Acid, Myristic Acid, Macrogol-8, Potassium Hydroxide, Lauric Acid, Polyethylene, Glycerin, Dipropylene Glycol, Ethanol, Menthol, Beeswax, (Daily Use) Fragrance, Ultramarines, Talc, Tocopheryl Acetate, Ethyl Cellulose, Disodium EDTA, BHT, Silica, etc.
Judging from the ingredient list, this is a typical soap-based formula. Alcohol and menthol create a cool and refreshing skin feel, and talcum powder and silica are used as scrub particles. The product name also specifically highlights the three characteristics of deep layer, cleansing, and scrub. It can be used occasionally in summer, and the skin feels very refreshing, but long-term use will cause certain negative effects on the skin.
Some products do not add potassium hydroxide and various organic acids but directly add fatty acid salts, such as potassium laurate, potassium myristate, potassium palmitate, and potassium stearate, which are also soap-based products.
- For example, a facial cleanser has the following ingredients:
Water, Potassium Myristate, Stearic Acid, Glycerin, Dipropylene Glycol, Potassium Stearate, Potassium Cocoyl Glycinate, Macrogol-75, Potassium Laurate, Kaolin, Macrogol-6, Polyethylene Glycol Ethylene glycol-32, sodium trehalose sulfate, hydrogenated lecithin, sodium hyaluronate, hydrolyzed collagen, etc.
Potassium myristate is the product of the reaction between myristic acid and potassium hydroxide, so the product is essentially a soap-based formula.
If potassium hydroxide is placed very late in the ingredient list, the amount added is small and not necessarily a soap-based formula.
- For example, a baby facial cleanser has the following ingredients:
Water, Glycerin, Stearic Acid, Palmitic Acid, Myristic Acid, Lauric Acid, Lauramidopropyl Hydroxybetaine, Cocamide MEA, Sodium Hyaluronate, Yeast Extract, Aloe Vera Extract, Potassium Hydroxide, Methylparaben, propylparaben, bis(hydroxymethyl) imidazolidinyl urea, iodopropynyl butyl carbamate, etc.
Potassium hydroxide is ranked after sodium hyaluronate, and it can be inferred that its content will not exceed 1%. There are 4 kinds of organic acids in the front, and their concentration will not be lower than potassium hydroxide. According to the stoichiometric relationship, it is inferred that potassium hydroxide is not enough to neutralize these organic acids, so this product is not a soap-based formula.
The antiseptic system of the product is two kinds of parabens and formaldehyde releaser bis (hydroxymethyl) imidazolidinyl urea and iodopropynyl butyl carbamate. The safety is not very good.
The core ingredient of a soap-based facial cleanser is potassium hydroxide, which is easy to cause over-cleaning. It is only suitable for healthy oily skin in summer and can be used for weekly care in spring, autumn, and winter.