Thioglycolic acid corresponding disulfide (2-[(carboxymethyl)disulfanyl]acetic acid or dithiodiglycolic acid): Thioglycolic acid, usually as its dianion, forms complexes with metal ions. Such complexes have been used for the detection of iron, molybdenum, silver, and tin. Thioglycolic acid reacts with diethyl acetylmalonate to form acetylmercaptoacetic acid and diethyl malonate, the reducing agent in conversion of Fe(III) to Fe(II). Scientist David R. Goddard, in the early 1930s, identified TGA as a useful reagent for reducing the disulfide bonds in proteins, including keratin (hair protein), while studying why protease enzymes could not easily digest hair, nails, feathers, and such. He realized that while the disulfide bonds,
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