* Scalp Oil (Sebum): The scalp naturally produces sebum, an oily substance that lubricates and protects the hair. Sebum travels up the hair shaft, coating it and making it appear oily.
* Porous Structure: Hair is porous, meaning it has tiny holes or spaces along its structure. These pores allow the hair to absorb liquids, including oils.
* Hair's Chemical Composition: Hair is primarily made of keratin, a protein. Keratin molecules have regions that are attracted to oil (hydrophobic) and regions that are attracted to water (hydrophilic). The hydrophobic regions allow the hair to attract and hold onto oily substances.
* Surface Area: The surface area of hair, especially curly or textured hair, is larger than straight hair. This increased surface area provides more places for oil to cling to.
In summary, hair absorbs oil because it's coated in natural oils, has a porous structure, and contains molecules that are attracted to oil.