The cleaning action of dry ice blasting is due to three factors:
KINETIC ENERGY: Compressed air propels the dry ice particles up to supersonic speeds. Though light in weight, they puncture the contaminate and chip away at it, thereby opening the surface of the contaminate.
MICRO-THERMAL SHOCK: An immediate and localized cold shock to the contaminate versus a substrate (surface) which cools down much less. This action promotes a contact break between contaminate and substrate.
SUBLIMATION: As the dry ice sublimes (becomes a gas) on impact, it increases up to 700% of its volume from solid to vapour, when it enters the cracks within the contaminate. This gas expansion, breaking up the contaminate from within, is the major factor responsible for the dry ice cleaning effect.