Filing back and forth won’t harm the natural nail plate if the proper abrasives and the correct downward pressure are used — meaning a 180-grit or higher file and a light touch. Grits below 180 should not be used on the natural nail because they cause excessive damage no matter what type of filing motion is used. Also, the heavier the downward pressure, the more damage that will occur to the nail plate. The natural nail will become weaker as layers are removed from the surface, which should be avoided.
When prepping a nail, nail technicians should only remove the shine caused by oil on the surface. If this is done correctly, less than 2% of the thickness of the nail plate will be removed, which is barely visible to the eye. If the nail plate is visibly thinner after removing nail enhancements, it is probably due to overly aggressive abrasives or filing techniques before the acrylic application. This is an all-too common problem in our industry. Nail technicians should be careful to avoid roughing up the nail plate; that’s not your job. The first job of every nail professional should be to protect the natural nail. One good way to achieve this is to avoid overfilling, aggressive abrasives, or too much downward pressure. They’re called nail enhancements for good reason. They are designed to beautify and enhance the natural nail plate, not replace it. -Doug Schoon