1. Classification by dosage form (product form)
(1) Solid (soap)
It is convenient to use and has a good feel. It is a traditional cleansing product; but the skin feels tight after use.
(2) Cream, paste
Weakly acidic-alkaline, special for the face, excellent feel and foaming performance, easy to use.
(3) Liquid/viscous liquid (such as cleansing gel)
Weakly acidic-alkaline, weakly acidic has relatively weak cleaning power, and alkaline has stronger cleaning power.
(4) Granular/powdered (cleansing powder)
It is easy to use. Since it does not contain water, papaya enzyme or other enzymes can be infiltrated.
(5) Foam
There are two types: one is directly sprayed in the form of foam; the other is squeezed out in liquid form and foams during use (also called post-foaming).
2. Classification by main surfactant types
Surfactants have effects on the skin including skin tightening, roughening and irritation. If we classify according to the main surfactant types (hereinafter referred to as surfactants), facial cleansers can be divided into soap-based, amino acid-based and compound-based facial cleansers.
(1) Soap-based facial cleansers
Soap bases are formed by neutralization of fatty acids and alkalis. Fatty acids generally include lauric acid, myristic acid, palmitic acid and stearic acid. The alkali used for neutralization is generally potassium hydroxide.
Soap-based facial cleansers have the characteristics of texture, rich foam, smoothness and density, strong cleaning ability, easy rinsing and refreshing after use.
Since fatty acid salts are alkaline, pure soap-based products have a pH of 9-10, which is not compatible with the skin pH of 5. Therefore, they are not gentle enough for the skin and can easily cause tightness and dryness after washing for people with fragile skin.
(2) Amino acid-based facial cleansers
Amino acid-based facial cleansers are neutral to weakly acidic facial cleansers with amino acid system surfactants as the main body and low-irritation cleaning base.
Amino acid surfactants have moderate detergency, good foaming performance, excellent flushing performance, good affinity with the skin, and low irritation. However, their disadvantage is weak foaming power.
There are many types of amino acid surfactants. The main amino acid cleansing products are glycine type, glutamic acid type, and methyl taurine type.
(3) Compound facial cleansers
Different surfactants have different experiences and characteristics. In order to develop facial cleansers with better use effects and achieve a balance between foam, cleaning efficiency, skin mildness, and pleasant and comfortable skin feel, surfactants with different characteristics are usually compounded.
For example: soap-based surfactants have fast foaming speed, fine and rich foam, and are easy to rinse off, but they will bring dry skin feeling after washing. The AES system has slightly weaker foaming performance and will feel greasy when rinsing. It is easier to adjust the soap base and AES compound to a product with rich foam and moderate refreshing and moisturizing feeling.
Other types of surfactant combinations will also have excellent synergistic effects. For example, using amino acid surfactants in combination with soap bases can reduce the irritation of soap bases; AES combined with amino acid surfactants can solve the problem of amino acid surfactants being difficult to thicken; APG combined with amino acid surfactants, etc.