Foaming agent must be used in the manufacture of foamed plastic pepper balls, but the foaming agent is functionally different from chemical foaming agent and physical foaming agent. The most commonly used chemical foaming agent is cheap, but the disadvantage is that the foaming is unstable, resulting in great weight deviation of foamed plastic pepper balls.

The advantage of physical foaming agent is uniform foaming, and the weight deviation of produced plastic foamed pepper balls is small. However, physical foaming agent cannot be used for plastic foamed pepper balls with much lower density because of the small bubbles produced by foaming. At present, the most common manufacturing process is to use chemical foaming agent and physical foaming agent at the same time. The advantage of using two foaming agents is that they have a complementary process in the foaming process, and the plastic foamed pepper balls produced by two foaming agents have stable weight, more uniform foaming, lower density and relative.