Frequently Asked Questions

Q: What is CO2 blasting?

A: It is a process in which dry ice particles are propelled at high velocities to impact and clean a surface. The particles are accelerated by compressed air, just as with other blasting systems. Today, most applications are able to use standard shop air, in the 80 - 100 psi range.

Q: How does CO2blasting remove contaminants?

A: It depends on what you are cleaning. If you are removing a brittle contaminant such as paint, the process creates a compression tension wave between the coating and the substrate. This wave has enough energy to overcome the bonding strength and literally pop the coating off from the inside out. If you are removing a malleable or viscous coating such as oil, grease, or wax, the cleaning action is a flushing process similar to high-pressure water. When the particles hit, they compress and mushroom out, creating a high velocity flow that actually flushes the surface.

Q: How does this differ from how sandblasting works?

A: Sandblasting is similar to using an ice pick whereas dry ice blasting is similar to using a spatula. Sand cuts or chisels away the contaminant. Dry ice lifts it away.

Q: What happens to the dry ice once it strikes the surface?

A: It sublimates and returns to the atmosphere as carbon dioxide (CO2 ) gas. CO2 is a naturally occurring element that constitutes less than 1% of our atmosphere.

Q: What happens to the contaminant?

A: Contaminates that are dry, wet, hard or soft can be swept up, vacuumed or sprayed away. The surface where contaminate were will be dry and clean.

Q: Will dry ice blasting damage the substrate?

A: The dry ice blasting process will not damage the substrate. The size and velocity of the dry ice pellets can be changed to remove the contaminate while being nonabrasive to the substrate.

Q: Can CO2 be used to clean hot online?

A: The process cleans best hot. Most contaminants have weaker adhesive strength when hot. In many applications, you may be able to clean three to five times faster hot than cold. In addition, because dry ice sublimates on impact, entrapment of the blasting media is not an issue. Grit entrapment is the reason those who clean with sand, walnut shells, or other grit media cannot clean online.

Q: Does the CO2 cool the substrate?

A: Yes, but generally not as much as you might think. The amount of cooling is dependent upon three main factors: mass of the targeted surface, dwell time, and ice usage rate. Typically, a tire mold may start at 350°F and drop to 325°F during cleaning. With a very thin mold, the drop can be much greater. Generally, however, cooling is not a concern and rarely affects the cleaning performance.

Q: Will the process create condensation?

A: It depends on the mass of the object you are blasting, your dry ice usage rate, there will be condensation if you cool the substrate below the dewpoint (the dew point varies depending on local climate). Of course, if you are cleaning a hot mold it is rare to have condensation because you seldom cool the mold below the dew point. Condensation is not a factor 85% of the time. When it is, it can be dealt with easily. The introduction of heated air or heat lamps usually eliminates condensation.

Q: How is dry ice made?

A: It is made from liquid carbon dioxide. Dry ice exists as a liquid only under high pressure. When it drops to ambient pressure (the normal pressure that surrounds us), approximately half turns to gas and half turns to solid. The solid, usually in the form of fluffy snow, is then compressed to form dry ice blocks, pellets, or nuggets.

Q: What is the difference between a one-hose system and a two-hose system?

A: In the two-hose system, the dry ice travels in one hose and the high-pressure air in another. The two are not mixed until just before the pellets exit the end of the nozzle. In a one-hose system, the pellets and air are mixed together in one hose.

Q: What are some successful rubber molding applications?

A: Virtually every major tire manufacturer uses CO2 blasting equipment to clean tire molds. A good rule of thumb in the rubber industry is, if you can see it, you can clean it with CO2.

Q: How is CO2 used in the food industry?

A: CO2 is perfectly suitable for use in this industry because it is food grade quality, the ingredient that provides the carbonation in soft drinks. It is used to clean ovens, conveyor belts, molds, dry mixers, laminators, and packaging equipment.

Q: Can CO2 be used to clean wood?

A: Dry ice blasting will raise the grain on the wood, leaving a finish similar to that of sandblasting. If you need a smooth wood finish, dry ice blasting is not the answer. The primary interest here has been in lead paint abatement. Most other removal methods create additional toxic waste. Because dry ice disappears as it strikes the surface, the only waste that must be disposed of is the paint itself.

Q: Is the system noisy?

A: Yes. Noise is a function of air volume and air velocity. Within the nozzle, the high velocity air causing turbulence, which creates noise, shears the stationary air. The level can range from 85 - 130 db. Hearing protection is required.

Q: Does the process generate static electricity?

A: Yes. Any dry air process will generate static electricity and dry ice blasting is no exception. All equipment used by A&H Dry Ice is designed with grounding devices. As long as both the blasting unit and the piece you are blasting are properly grounded, you are unlikely to have any static discharge problems.

Q: Is it okay to blast in an enclosed area?

A: Yes, with proper ventilation. Because CO2 is 40% heavier than air, placement of exhaust vents at or near ground level is recommended when blasting in an enclosed area. In an open shop environment, existing ventilation is sufficient to prevent CO2 buildup.