The most common injury at the nail-saloons the overfileing the natural nail plate.
The fingernail plate is made of about 100 layers of dead, flattened keratin cells. Thousands of nail cells. The nail plate of the hand is thinner, the toenail is thicker. The nail technicians often use heavy hand files, or drills, and overfile more, than the half of the nail plate. The thin nail plate will cause problems also for the client, and for the nail technician too. Only a 240 grit, or higher file allowed to work on natural nails.
Its also impossible of the materials (enhancements, nail polish, base coats...) to adhesion well to a thin, smooth nailplate. On the thin nail plate, the monomers can easily penetrate, cause allergic reactions. Unfortunetly, the most nail technician overfile the natural nailplate.
To the best adhesion, you must file down only the very top layers of the natural nail, wich cause the siny surface. This shine made from oil, and dust, on the nail plate. Use light touch, while file down only 3-4 layers of the natural nail (it's about 2-3%), so you let healthy the 97-98% of the natural nail plate.