Masking device for cosmetic hair treatment

A masking sheet comprising:

• a substantially flexible material member having a first surface adapted to be disposed adjacent to a portion of a client's hair, said first surface being encompassed by first and second longitudinal edges and first and second transverse edges and contiguous therewithin, said first and second longitudinal edges being substantially rectilinear and substantially parallel to one another, said first and second transverse edges defining respective first and second monotonically concave curves with respect to a transverse centerline of said masking sheet, said first and second transverse edges defining opposite ends, and substantially exhibiting mirror symmetry, across said transverse centerline of said masking sheet, said masking sheet being adapted to be folded along a transverse fold line so as to generally enclose and cover said portion of said clients hair.