Frequently Asked Questions
What is dry ice or CO2 blasting?
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 can use standard shop air in the 30-100 psi range.
How does it remove contaminants?
It depends on what you’re cleaning. If you’re 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’re removing a malleable or viscous coating such as oil, grease, or wax, the cleaning action is a flushing process like high-pressure water. When the particles hit, they compress and mushroom out, creating a high velocity snow flow that flushes the surface.
How does this differ from how sandblasting works?
Sandblasting is like using an ice pick, whereas dry ice blasting is like using a spatula. Sand cuts or chisels away the contaminant, while dry ice lifts it away.
What happens to the dry ice once it strikes the surface?
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.
What happens to the contaminant?
People sometimes think it disappears too, but it does not. All cleaning involves the relocation of dirt. When you mop a floor, the dirt moves from the floor, to the mop, to the water in the bucket. With dry ice, the dirt moves from an undesirable area to an area where you can better deal with it. If it is a dry substance, it generally falls to the floor where it is swept away or vacuumed during normal maintenance. If it is a wet substance like grease, you take a methodical approach like hosing down a driveway. You start at one end and guide the grease to the other end where it is vacuumed or squeegeed up.
Does dry ice cool the substrate?
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, cooling is not a concern, and only rarely does it affect cleaning performance.
Will the temperature drop damage the hot mold?
It depends on the mass of the mold. Large, heavy molds will not be harmed in any way because the temperature drop is insignificant compared to the mass of the mold. With thin molds where tolerances are critical, some testing may be required to determine if the temperature drop would alter the structure of the mold.
Will the process create condensation?
Once again, it depends on the mass of the object you’re blasting, your dry ice usage rate, and your dwell time. There will be condensation if you cool the substrate below the dewpoint (the dewpoint varies depending on local climate). If you’re cleaning a hot mold, it is rare to have condensation because you seldom cool the mold below the dewpoint. Condensation is not a factor 80% of the time. When it is, it can be dealt with quite easily. Using a hot air knife can be highly effective.
How did dry ice blasting technology originate?
Dry ice blast cleaning originated at Lockheed in the 70’s when a coatings engineer, Calvin Fong, was researching ways to strip paint off aircraft. The technology did not become commercially available until Alpheus bought the license and patents from Lockheed and introduced it to the marketplace in 1987.
Is the system noisy?
Yes. Noise is a function of air volume and air velocity. Within the nozzle, the stationary air is sheared by the high velocity air causing turbulence which creates noise. The level can range from 80-130 db, and hearing protection is required.
Do the contaminants or dry ice particles ricochet?
As long as it strikes the surface head on, dry ice does not ricochet because it sublimates (turns into a gas) on impact. As for the contaminant, you usually do not see or feel it as it disbonds and leaves the substrate. However, it is removed with some force which is why eye protection is recommended at all times.
What are the best cleaning applications for dry ice?
The range of cleaning applications for dry ice is phenomenal and is easily demonstrated in just a small sampling of our customer base: core boxes for Ford; delicate wiring in copy machines for Xerox; conveyors for Nabisco; tire molds for Michelin; dry ice blasting shines in cleaning production equipment online, because it eliminates the need for masking, cool down and disassembly.
Users minimize downtime which maximizes production efficiency. We have achieved outstanding results cleaning production equipment for foundries, molded rubber producers, food processors, printers, and the semiconductor industry. Dry ice blasting is also widely used in the nuclear industry for decontamination. Wherever waste volume or health risks are a concern, the viability of dry ice should be examined. Because dry ice disappears on impact, it creates no additional waste. Competing processes such as grit blasting or solvents often present disposal problems or health hazards.
How is dry ice blasting used in foundries?
Dry ice blasting equipment is used in foundries worldwide to clean core boxes and permanent molds. Not only does dry ice blasting increase production by decreasing downtime, but it also eliminates mold damage, preserving the critical tolerances and greatly extending the life of the expensive tooling. Dry ice foundry clients include major auto-makers like Chrysler, Ford, GM, Nissan, BMW, Mercedes, and Renault. However, you don’t have to be an industrial giant to enjoy the cost benefits of dry ice blasting. Many small to medium-sized foundries in the U.S. and Canada successfully use dry ice blasting equipment to clean online.
Can dry ice be used to clean hot online?
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 an important reason those who clean with sand, walnut shells, or other grit media cannot clean online.
What are some successful rubber molding applications?
Virtually every major tire manufacturer uses dry ice blasting equipment to clean tire molds, including B.F. Goodrich, Bridgestone, Dunlop, Firestone, Goodyear, Kelly, Michelin, and Uniroyal. We also clean rubber molds for manufacturers of gaskets, o-rings, shoes, and many other products. A good rule of thumb in the rubber industry is that if you can see it, you can clean it with dry ice.
How is dry ice used in the food industry?
Dry ice is perfectly suitable for use in this industry because it is food grade quality—the same ingredient that provides the carbonation in soft drinks. It is used to clean ovens, conveyor belts, molds, dry mixers, laminators, and packaging equipment. Nabisco, Hunt-Wesson, Uncle-Ben’s, Pillsbury, Frito-Lay, and General Mills are among the food industry leaders who clean using dry ice blasting systems.
What are some examples of applications where dry ice does not work well?
Dry ice blasting will not etch or profile most surfaces. If you need to clean large quantities of small parts, dry ice is not generally as efficient as other alternatives such as ultrasonics. Because dry ice blasting is primarily a line-of-sight cleaning process, if you can’t see what you need to clean, you probably can’t clean it with dry ice.
Does the process damage the substrate?
Generally, no, but it depends on the substrate. There is an energy threshold at which disbonding will occur and a threshold at which damage will occur. When the disbonding threshold is lower than the damage threshold, you can clean. If the reverse is true, damage can occur. Most of our applications deal with production equipment (cast iron, tool steel, tool grade aluminum), so there is no damage. We do have success with softer substrates such as plastics, wiring, pure copper, and fabrics, but these must be examined on a case-by-case basis.
Can dry ice be used to remove paint?
Yes, however, the removal rate is dependent on many factors including: the underlying surface profile of the substrate; the thickness of the coating; the adhesive bond strength of the coating; and the cohesive strength of the coating (generally a function of age). Paint removal rates can vary dramatically, from 300 square feet/hour down to 1 square foot/hour. Generally, if you have concerns with contamination, toxic substances, waste disposal, or substrate damage, dry ice blasting should be considered as a cleaning option. Otherwise, grit blasting is probably a more efficient method for paint removal.
Will dry ice remove greases, oils, or weld slag?
A methodical approach, similar to hosing down a driveway, is required if dry ice is to be effective on these and other wet contaminants. You must start at one end and work the grease to the other end where it can pass through a grate or be vacuumed or squeegeed for disposal. Some customers use a paper or plastic backdrop to catch the wet contaminant as it is removed from the substrate. Dry ice doesn’t dissolve the oil and doesn’t make it disappear so you must have an acceptable way of handling it when it is relocated by the blasting process.
Can dry ice be used to remove rust?
It tends to remove the loosely adhered oxidation and salts but will not remove deeply adhered oxidation. You will not get a white metal finish. To do that you have to remove the surface metal, something the dry ice blasting process cannot do. Of course, in many applications, this is a major advantage because it preserves the surface integrity of the substrate.
Will dry ice clean glass?
It can, but some prior testing is required to avoid shattering the glass. Wickens Dry Ice Blasting produces a Viking 100 Snow Horn that customers use to clean glass monitors before applying a non-glare coating. We have others who use it to clean optics for cameras, fiber optics and other high-quality glass components. To clean glass with solid dry ice, it is important to remember that a certain impact energy is required to disbond the contaminant. If that energy level is high enough to also shatter the glass, you cannot clean using this process.
Can dry ice be used to clean wood?
Yes indeed. One of the exciting areas of dry ice use today is in mould remediation and fire restoration. Dry ice blasting will slightly raise the grain on the wood, leaving a finish similar to that of very light sandblasting. If you need a smooth wood finish, dry ice blasting will have to be followed by sanding or some other smoothing method. Because dry ice disappears as it strikes the surface, the only waste that must be disposed of is the removed contaminant and some wood fiber particles.
Do-It-Yourself Blasting FAQs
How much air will I need to clean effectively?
It is typical to operate at about 90 psi with 130 cfm, however your needs will depend on your application. Triventek designs nozzles that clean effectively while using as little air as possible, and makes it easy and inexpensive to move from one nozzle to another.
What blasting pressures are possible?
Most of our standard gun configurations are rated up to 125 psi, which is well above the 90-100 psi used in the vast majority of applications.
How much dry ice should I expect to use?
This is an important question to ask because the amount of dry ice you need to clean effectively can vary dramatically within the industry. With Triventek equipment, most customers use 1½-2 pounds per minute while the trigger is engaged. Of course, when you are not cleaning, you won’t be pulling the trigger constantly. At a rate of 2 pounds per minute with 50% trigger time, you would use 60 pounds of dry ice in an hour.
How do I store my dry ice?
Since dry ice is -109°F/-78.5°C, putting it in a freezer doesn’t really help. The best way to extend your shelf life is to store the ice in an insulated bin. Depending on the quality of the bin and how much ice you are storing, your loss due to sublimation should range from 2% to 10% per day. For your convenience, the Dry Ice Tote is available through Wickens Dry Ice Blasting. It holds up to 570 pounds of pellets, features a hinged lid, and includes casters to make it easy to move around the shop floor. The tote was specially designed to withstand the extreme temperatures, payload, and rugged use associated with the dry ice industry.
What are the primary safety issues relating to the use of dry ice blasting systems?
One safety issue, as in any factory setting, is protecting workers from moving parts. Triventek equipment is designed so that there is no access to moving parts. Another issue is the temperature of the dry ice. At -109°F/-78.5°C, we recommend you never handle it directly without gloves. Proper PPE for the contaminant involved is required and just as in sand blasting or steam cleaning, the gun should never be pointed at anyone or serious injury could occur. The issue that comes up most often is noise.
Is it okay to blast in an enclosed area?
Yes, with proper ventilation. Because CO2, or dry ice, 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 undue CO2 buildup.
Does the process generate static electricity?
Yes. Any dry air process will generate static electricity, and dry ice blasting is no exception. As long as both the blasting unit and the piece you are blasting is properly grounded, you are unlikely to have static discharge problems.
Does dry ice replace sandblasting/bead blasting/water blasting, etc.?
They are all tools in the toolbox. Consider that there are many types of hammers: ball peen; tack; claw; sledge; and so on. Could each do the job of the other? Perhaps, but the ideal toolbox would include each, because each has specific capabilities that it does better than any of the others. Triventek equipment should be in your toolbox if you are concerned with downtime, entrapment, waste volume, or equipment damage.
What is the difference between a one-hose system and a two-hose system?
In a 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. The primary advantage of a two-hose system is simplicity. In a one-hose system the pellets and air are mixed together in one hose at an air lock and travel the complete length of the hose.
Although generally a one-hose system uses more ice, in the Triventek Triblast-3 one-hose system, ice consumption can be adjusted to permit very low ice consumption. In areas where there is a substantial thickness of contaminant the single hose system can permit added blasting aggression and faster cleaning. With the Triblast-3 system, customers receive the advantages of simple design, ease of maintenance, and adjustability all in one unit.
How do Triventek pellet blasters compare to the competition?
Triventek engineers are responsible for introducing to the marketplace a truly economical, yet versatile pellet blaster. the Triblast-2 offers aggressive cleaning capabilities but work equally well at low pressures where the majority of applications exist and they do so while using less ice. They are the easy to use, reliable, and the lowest maintenance units on the market.
Are the portable blasting units easy to move around?
One person can easily roll all the Triventek portable blaster around the shop floor without any special equipment. The Triblast-2 is small enough to carry upstairs for complete blasting freedom.
Will I need an air dryer?
Wickens equipment is designed to operate with clean, dry air which most plants are able to provide, so an additional air dryer is generally required only when using the equipment with portable diesel compressors. The Wickens Chiller/Dryer was developed to meet this need. You should, however, always blow down your in-plant air lines before hooking them up to your dry ice blasting unit. This will eliminate water and sediment that may be present and prevent these impurities from entering the equipment.
What other equipment will I need?
If you plan to make your own pellets, you will need a source of liquid CO2 and the means to store it. Otherwise, you will need a source of dry ice. You will need a Dry Ice Tote or similar storage device to store your dry ice supply. You need an air source. Standard shop air is sufficient for most applications. For the electric Triblast-2, you also need a source of electricity.
How much equipment maintenance is required?
Very little. Triventek blast units are designed to provide years of trouble-free use with a minimum of maintenance. You must periodically examine the airlock for wear and hoses for cracks and abrasions—that’s it.
Can I vary the dry ice consumption rate?
Yes, you can easily vary the rate at the control panel on the Triblast-2 blasters.
What should I do if my blast hose is cracked?
Replace it. The hoses carry high pressure air and could lead to problems if cracked or abraded.
Dry Ice FAQs
How is dry ice made?
Dry ice is made from liquid carbon dioxide and 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.
How are dry ice pellets made?
Pellets are made by taking liquid CO2 from a pressurized storage tank and dropping it to ambient pressure to produce snow. The snow is then pushed through a die to make pellets. The Triventek system is a mechanical extruder process in which the pellet extrudes through 3 easily interchangeable die plates.