In addition to the index of mesh size, sandpaper can also be divided into three types of raw materials: dry sandpaper, water resistant sandpaper, and sponge sandpaper.


1、 Dry sanded paper


There is not much difference between dry sandpaper and water resistant sandpaper, except that one can only be used dry when afraid of water, and the other can be used dry or dipped in water when not afraid of water.


Dry sandpaper is a type of sandpaper that can only be used dry, and can be used directly. The adhesive used for the base paper and bonding abrasive is not waterproof, and if used with water, it will quickly wear out and become useless, resulting in waste. However, the gap between the abrasive particles of dry sandpaper is larger than that of water resistant sandpaper. In theory, its grinding efficiency will be higher than that of water resistant sandpaper with the same mesh size, and the grinding marks will also be relatively significant.


2、 Water resistant sandpaper


Water-resistant sandpaper or water frosted paper, made of waterproof materials, is not afraid of moisture and can be used in environments with water. The abrasive particles are arranged more densely than dry sandpaper, and the grinding marks are more uniform. If used for drying, it is relatively easier to be blocked by polished debris in the gaps. So it is generally used with water to allow the polishing debris to be washed away with the flow of water during the polishing process. In addition, water resistant sandpaper can be used in water environments to keep all polished debris in the water without floating in the air, which is more friendly to the working environment and physical health.


3、 Sponge sandpaper


Sponge sandpaper, whose base is a sponge with a certain thickness instead of Kraft paper and other materials. A soft substrate gives sandpaper a certain degree of elasticity and adhesion, making it suitable for polishing curved surfaces. But in reality, due to the different forces applied during the push out and pull back, there may be slight deformation in the hand's movements, resulting in the polished surface becoming curved. This situation is particularly outstanding on various small-scale surfaces. Large surfaces can be polished back and forth as appropriate.