Dry ice-blasting is a form of carbon dioxide cleaning, where dry ice, the solid form of carbon dioxide, is accelerated in a pressurised air stream and directed at a surface in order to clean it.
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.
The frigid temperature of the dry ice -109.3°F or -78.5°C "blasting" against the material to be removed, causes it to shrink and lose adhesion from its sub surface. Additionally when some of of dry ice penetrates through the material to be removed, it comes in contact with the underlying surface. The warmer sub surface causes the dry ice to convert back into carbon dioxide gas. The gas has 800 times greater volume and expands behind the material speeding up its removal. Paint, oil, grease, asphalt, tar, decals, soot, dirt, ink, resins, and adhesives are some of the materials removed by this procedure. Only the removed material must be disposed of, as the dry ice sublimes into the atmosphere.
In some instances where there has been a fire at a property, dry ice cleaning can remove the charred residue from different surfaces including timbers that may have been ordinarily replaced when they are actually structurally sound. We have our own equipment and trained operatives so can carry out this type of work along with any follow up works required alleviating the need to emply multiple contractors