Hair coloring by lay people may not be sufficiently accurate. Hair that has been damaged by excessive exposure to chemicals is considered "over-processed". This results in dry, rough and fragile hair. In extreme cases, the hair can be so damaged that it breaks off entirely. The main cases of hair breakage are: Lack of moisture and oils, poor diet, stress, over processing or illness. Skin and fingernails are made of a similar type of keratinized protein as hair. That means that drips, slips and extra hair tint around the hairline can result in patches of discolored skin. This is more common with
Artificial nails polymer with "liquid monomer", usually ethyl methacrylate mixed with some inhibitor, forms a malleable bead. This mixture begins to cure immediately, continuing until completely solid in minutes. Another common material is acrylic gel, which contains photoinitiators that prevent its curing until exposed to either ultraviolet light within a certain wavelength. Some new techniques, too, have been invented, attempting to make obsolete the two outlined above. Dipping, for instance, involves painting nails with special primer and base coats, then repeatedly painting the nail with a clear coat and submerging it in powder. Nail products are available in a variety of colors