Abstract: An improved nail hardener comprises a nitrocellulose-base nail lacquer and fiber glass, 10 microns in diameter by 800 microns long. The nail hardener forms a film approximately five times as strong as the film formed by conventional nail hardener. A method of strengthening and protecting fingernails against chipping and cracking and concealing imperfections of the nails by coating said nail with a nail hardener containing fiber glass is also provided.