Dry Ice Blasting works because of three primary factors: pellet kinetic energy, thermal shock effect and thermal-kinetic effect. As with other blast media, the kinetic energy associated with dry ice blasting is a function of the particle mass density and impact velocity. Since dry ice particles have a relatively low hardness, the process relies on high particle velocities to achieve the needed impact energy. The high particle velocities are the result of supersonic propellant or air stream velocities. Even at high impact velocities and direct “head-on” impact angles, the kinetic effect of solid dry ice particles is minimal when compared to other media (glass, sand, plastic bead, etc.). This is due to the relative lack of hardness of the dry ice particles and the almost instantaneous phase change to a gas on impact, which effectively provides an almost nonexistent coefficient of restitution in the impact equation