Dry Ice Blasting (Cryogenic Cleaning)
The dry ice blasting process consists of propelling dry ice (CO2) particles at supersonic speeds which impact and clean the surface of the object being blasted. The particles are accelerated by compressed air, just as with other blasting methods. Overall, there are three steps involved in dry ice blasting.
During blasting, dry ice pellets are propelled out of the blasting gun at supersonic speed and impact the surface. The energy transfer knocks off the contaminant without abrasion. The force of this impact is the primary means of cleaning.
The cold temperature during dry ice blasting of the dry ice pellets hitting the contaminant creates a micro-thermal shock (caused by the dry ice temperature of -109º F) between the surface contaminant and the substrate. Cracking and delamination of the contaminant occurs furthering the elimination process.
The final phase of dry ice blasting has the dry ice pellet explode on impact, and as the pellet warms it converts to a harmless CO2 gas which expands rapidly underneath the contaminant surface. This helps loosen the contaminant so it flakes off. The dry ice evaporates, leaving only the contaminant for disposal.