what makes hair curly

The shape of the hair follicle is a major determinant of hair texture, and oval follicles produce curly hair while round follicles produce straight hair. The flatter the oval shape, the curlier the hair. The angle that the follicle sits in the dermis, the below-surface skin, is another key factor in determining curl. If the follicle bulb sits at a 90-degree angle with the skin’s surface, the hair is likely to grow out straight. The more angled it is, the kinkier the hair. The hair bulb, located at the base of the hair follicle, also plays a role in determining curl. For those with curly hair, the bulb is slightly hooked. The amount and placement of disulfide bonds in the hair shaft also affect the degree of curl. Straight hair has disulfide bonds evenly distributed all over the hair shaft, but in curly hair, they bunch up on one side, creating beautiful waves, curls, or kinks. These temporary bonds are what make hair curl up on a humid day, and they change every time hair gets wet and dries. In summary, the shape of the hair follicle, the angle of the follicle, the hair bulb, and the amount and placement of disulfide bonds in the hair shaft all contribute to making hair curly.