The density of 0.68 caliber plastic solid pepper ball is consistent with the density of material in theory, but the density of plastic pepper ball is different from that of the material used to make it because of the change of pressure and water absorption during the material processing.

The manufacture of 0.68 caliber plastic pepper ball is mainly made by injection molding process. During the injection molding process, the density of plastic pepper ball will change due to the pressure. The greater the pressure in the injection molding process, the greater the density of plastic pepper ball. On the contrary, the smaller the density of plastic pepper ball. Another factor that affects the density of plastic pepper ball is the water absorption rate. When the plastic pepper ball absorbs water, the density will change, and the more water it absorbs, the greater the density will be. Also, when producing plastic pepper balls, bubbles will be generated. Because there are bubbles inside the plastic pepper balls, the density of the plastic pepper balls becomes smaller. These are the factors that affect the density of the plastic pepper balls.