Polyester but not cotton or wool textiles inhibit hair growth.

The effect of different types of textile fabrics on hair growth was investigated in 40 mongrel dogs divided into 5 groups. An area of 10 x 20 cm on the dog's back was shaved; half of this area was covered by a textile patch of 100% polyester material in the 1st group, 100% cotton in the 2nd group, 100% wool in the 3rd group and a 50%/50% polyester/cotton blend in the 4th group. The remaining half of the shaved area in the 4 groups as well as the whole area in the 5th group (control) were left uncovered. The textile patch was worn for 2 months. The polyester-covered hair grew at a significantly lower rate and density than in the uncovered area of the same animal and the controls (p < 0.01). The hair color was similar to that of the surrounding uncovered hair. This is in contrast to cotton- and wool-covered skin area which showed nonsignificant differences in hair density, growth rate and color (p > 0.05) against the uncovered area and controls. In the polyester-covered skin, a thinning of the epidermis of the skin was noted microscopically with fragmentation and vacuolation of the hair follicle pulp. The study has shown that the polyester material generated electrostatic potentials, which may have inhibited hair growth, whereas cotton and woolen textiles did not. Friction between the polyester textile and the skin generates electrostatic charges which are suggested to create an 'electrostatic field' that seems to be responsible for the inhibited hair growth.