01
Essentially, what are the ingredients of silicone oil?
The ingredients in silicone oil include: dimethicone, dimethiconol, and amodimethicone.
Broadly speaking, the shampoo ingredient list does not contain silicone oil; products with ingredients such as polydimethyloxane, dimethiconol, and amodimethicone can be called silicone-free shampoo.
On the contrary, it is silicone oil shampoo. The non-toxicity of "silicone oil" is recognized. It can be used in washing and care products and has become a mainstream additive over the years. Its functions cannot be ignored, such as filling in hair scales and smoothing hair. , reduce static electricity caused by friction between hair, making hair easier to manage.
Silicone oil is a chemical substance and is impermeable to water. It has the same properties as other chemical substances. If you use shampoo containing silicone oil for a long time, even if the silicone oil content does not exceed the standard, it will have an irritating effect on the scalp over many years, which will lead to hair loss and scalp damage. Dryness, itching, etc.

02
So why is "silicone oil" added to shampoo products? This starts with the structure of the hair.
We can see with the naked eye that hair is a cylinder with a smooth surface, but under a microscope, the structure of hair is another story. Hair can be divided into three layers, of which the outermost layer is the epidermis (hair cuticle layer), which mainly contains 8-10 overlapping, hard layered cuticles (hair cuticles), similar to tiles on a roof. These "tiles" overlap each other and wrap the entire hair, protecting the inner layer of the hair; determining the appearance and gloss of the hair; the hair scales open when exposed to alkali and heat, and close when exposed to acid and cold; the quality accounts for 10%.
The "tile" structure of the hair comes out, and when washed, it feels very rough and not smooth. In addition, hair is negatively charged, and with this cuticle structure, it is easy to absorb dust and dirt.
The role of silicone oil: As a light, smooth and breathable oil, silicone oil can form a protective film on the surface of the hair, wrapping the hair, making the hair smooth, soft and shiny. It can also prevent moisture from evaporating and prevent hair from drying out. The film formed by silicone oil on hair has a porous structure and cannot "clog pores" as some people assume. It is precisely because of these excellent effects of "silicone oil" that silicone oil is added to most shampoo products on the market.