In the newly bought PET Protective Film are generally not "open", should be first in the coarse grinding stone grinding out the PET Protective Film, and then in the fine grinding stone grinding to sharp; with dull PET Protective Film, if first put in a concentration of 10% salt water soak for a few moments, and then grinding, while grinding side dripping with salt water, so that the PET Protective Film grinding both fast, and grinding sharp; PET Protective Film with dull, try not to be on the edge of the cylinder or the bottom of the bowl on the grinding and scraping, so as not to damage the blade; PET Protective Film after use, to insert in the PET Protective Film frame, do not throw, to avoid touching damage to the edge; PET Protective Film to be often sharpened, sharpening to do the same number of times positive and negative. Grind both ends with the middle; PET Protective Film are generally placed in a ventilated, dry place, away from water and gas, etc.