Answer: Most distortion is caused by pits left where serious scratches are repaired. Imagine that some part of intact glass sags. There must be obvious deformation. However, the same pit expanded in area will be quite gradual and difficult to see from the front. It might be observed when seen carefully from one side or from a nearly horizontal angle. When you use a grinding sheet of 2 or 3 inches contained in our product for repairing general or shadow glass scratches, you can hardly see deformation. Facing a bit serious scratches or welding slag and burns, you may consider the use of a grinding sheet of 4, 5, or 6 inches for repair. The larger the diameter of grinding sheet is, the bigger the grinded area is andthe better the effect of repair is. This is because a bigger grinding sheet expands the grinded area, making the repair area much gentler.