Method 1: Wash it in warm water, wash it with soap after grease, dry it with a napkin, and then put it in a cool and windy place to blow on it. Be careful not to be exposed to the sun, silicone is a strong corrosion resistant material.
Method 2: Silicone mobile phone case will be very loose for a long time, which is the performance of silicone aging, there is no good way to change its physical properties, the only feasible solution is to add a piece of cardboard on the back of the mobile phone, which is equivalent to thickening the machine after the cardboard can be made with a personality pattern, the thickness can be selected according to the tightness.
Method 3: Put the phone cover in the microwave oven for ten minutes, the temperature is about 200°. If all else fails, buy a new phone case.