Dry-ice blasting

Dry ice-blasting is a form of carbon dioxide cleaning, where dry ice, the solid form of carbon dioxide, is accelerated in a pressurized air stream and directed at a surface in order to clean it. An alternative media for non-abrasive blasting is water-ice, known as ice blasting.

The method is similar to other forms of abrasive blasting such as sand blasting, plastic bead blasting, or sodablasting substituted for dry ice as the blasting medium. Dry-ice blasting leaves no chemical residue as dry ice sublimates at room temperature.

Dry-ice blasting involves propelling pellets at extremely high speeds. The actual dry-ice pellets are quite soft, and much less dense than other media used in blast-cleaning (i.e. sand or plastic pellets). Upon impact, the pellet sublimates almost immediately, transferring minimal kinetic energy to the surface on impact and producing minimal abrasion. The sublimation process absorbs a large volume of heat from the surface, producing shear stresses due to thermal shock. This is assumed to improve cleaning as the top layer of dirt or contaminant is expected to transfer more heat than the underlying substrate and flake off more easily. The efficiency and effectiveness of this process depends on the thermal conductivity of the substrate and contaminant. The rapid change in state from solid to gas also causes microscopic shock waves, which are also thought to assist in removing the contaminant. Dry Ice Blasting is nonabrasive, nonconductive and nonflammable. Dry Ice Blasting generates no additional waste or secondary contamination unlike media and water blasting.

The ice used can be in solid pellet form or shaved from a larger block of ice. The shaved ice block produces a less dense ice medium and is more delicate than the solid pellet system.

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