Dry ice blasting

This article explains how dry ice blasting works, what it is good at, its limits and safety points, and which tools to use when a steel surface needs to be cleaned and profiled for coating.

Dry ice blasting, or CO2 blasting, is a cleaning technique in which solid CO2 is accelerated in a pressurised air flow and directed at a surface to clean it. Compared with other blast cleaning methods it is a clean technique: it removes dirt, oil, grease and some paints and coatings, and because the dry ice sublimates there is no spent blast media to collect. Only the removed contamination itself has to be disposed of, which considerably reduces secondary waste.

What is dry ice blasting?

Dry ice blasting is a process that uses solid carbon dioxide (CO2) pellets, known as dry ice, blasted at high speed to clean surfaces. It is sometimes called dry ice cleaning, cryogenic blasting or CO2 cleaning. When the pellets hit the surface, the dry ice sublimates (changes directly from solid to gas) and loosens dirt, oil, grease and other contaminants.

The process is used on a variety of surfaces, such as metal moulds, machinery, electrical equipment and conveyor systems. Because it is dry and non-abrasive, it is widely used for industrial cleaning where the substrate must not be damaged or where water and chemicals are unwelcome. For a more detailed look at its limits, see our page Dry Ice Blasting: How It Works and What It Can't Do.

How does dry ice blasting work?

Dry ice blasting works on the principle of accelerated particles striking a surface and sublimating on contact. Solid CO2 particles are propelled with compressed air onto the surface. Research describes three combined mechanisms: thermal shock as the very cold pellets cool the contamination, kinetic energy from the compressed-air stream, and sublimation of the pellets, whose expansion into gas helps lift the loosened material away.

Because the pellets turn into gas, they leave no chemical residue and no blast media to clean up. The removed dirt or coating still falls to the floor or becomes airborne and has to be collected. That makes dry ice blasting a useful cleaning method for many industrial and commercial applications, but it is a cleaning method rather than a surface preparation method for coating steel.

What are the advantages of dry ice blasting?

The main advantage of dry ice blasting is that it is a non-abrasive form of cleaning. It does not damage the surface being cleaned while still removing dirt and grime. It also uses no water and no cleaning chemicals, so there is no wastewater or solvent to treat and items can often be cleaned in place.

What are the disadvantages of dry ice blasting?

• Cost and energy. The method requires specialised equipment, training and large volumes of compressed air. Producing that compressed air and the pellets is energy-intensive.
• Dry ice supply. Dry ice is manufactured from captured carbon dioxide and sublimates continuously during storage, so it must be produced or delivered close to the time of use. Pellets also degrade with storage, especially in humid conditions.
• Noise. Many machines reach around 120 dB(A), so hearing protection is essential.
• Cold. The extreme cold can affect delicate components of the item being cleaned.
• No anchor profile. Because it is non-abrasive, dry ice blasting does not roughen the substrate. It does not produce the anchor profile most protective coatings need, and it is not designed to remove tightly adherent rust or mill scale.

What equipment is needed for dry ice blasting?

Dry ice blasting requires specialised equipment: a dry ice blasting machine, a high-capacity compressed-air supply, a blasting hose and nozzle, dry ice storage and safety equipment. This makes it less flexible than hand-held power tools such as our Bristle Blaster® and MBX®, and the equipment cost is high, which is a significant disadvantage for smaller jobs.

What media is used for dry ice blasting?

The media used for dry ice blasting is solid carbon dioxide (CO2), also known as frozen CO2. Blasting machines generally use small pellets, typically 3 mm in diameter or smaller; some machines shave larger blocks into fine particles for delicate cleaning.

Is dry ice blasting safe?

Dry ice blasting avoids toxic blast media and cleaning chemicals, but it has hazards of its own that must be controlled:

• Asphyxiation. Dry ice is at about −78 °C (−109 °F) and turns into large volumes of CO2 gas. In poorly ventilated or confined areas this can raise CO2 concentrations to dangerous levels; the gas is heavier than air and collects at low points.
• Cold burns. Contact with dry ice or surfaces it has cooled can cause cold burns and frostbite.
• Noise and particles. High noise levels require hearing protection, and the removed contamination can become airborne, so eye and respiratory protection follow the risk assessment.

Dry ice blasting produces no secondary blast media or run-off, which keeps its environmental footprint low for many industrial cleaning tasks.

What are the alternatives to dry ice blasting for surface preparation?

Where the goal is cleaning, dry ice blasting competes with methods such as soda blasting and other media covered in 10 types of abrasive blasting. Where the goal is preparing steel for a protective coating, the surface must be cleaned to bare metal and profiled, and that calls for a different type of tool.

The Bristle Blaster® and MBX® from MontiPower® are hand-held alternatives to blasting equipment. With their specially developed technology and patented belts, they remove corrosion and coatings without loose abrasives, which makes them practical for smaller and hard-to-access areas where setting up any blasting process is inefficient.

The Bristle Blaster® also creates a profile comparable to blasting. In documented tests on standard steel it produces cleanliness comparable to ISO 8501-1 Sa 2½ / SSPC-SP 10 and a 65–85 µm Rz anchor profile; results vary with steel grade, rust grade, belt and technique. The MBX® is designed for vehicle bodywork panels and thin sheet, where it removes rust, paint and underseal; it is not intended for preparing structural steel to a protective-coating grade. For a full comparison of options, see alternatives to sandblasting steel.

How do MontiPower® bristle tools work?

The Bristle Blaster® and MBX® are hand-operated tools fitted with a rotating belt of specially designed bristles with sharpened, bent (kneed) tips.

The belts rotate at a controlled speed, around 2,200 rpm on the Bristle Blaster® Ultimate Cordless. On the Bristle Blaster®, the tips are briefly held back during each rotation by the accelerator bar. When released, they strike the surface with high kinetic energy and immediately rebound. This impact removes corrosion and coatings and leaves a micro-indented surface texture: the principle of bristle blasting. That makes it a practical surface preparation method in many sectors and an alternative to blasting with abrasives.

Alternatives to blasting with abrasives in different sectors

Traditional abrasive blasting can be harmful to people and the environment through dust, spent abrasive and, with some media, respirable crystalline silica. That makes grit-free tools such as the Bristle Blaster® a good fit for surface preparation in the marine and offshore and industrial sectors. Grit-free is not dust-free, however: the rust and coating removed still become particles, so extraction and respiratory protection follow the site risk assessment.

Convenience and effectiveness also matter. In public infrastructure, blasting bridges, rail and highway structures is time-consuming, labour-intensive work under time pressure, and it exposes workers to fine particles. For spot repairs, welds and smaller areas, the Bristle Blaster® can replace much of that blasting work.

Frequently asked questions

Does dry ice blasting remove rust?

Dry ice blasting can remove loose rust and surface contamination, but it is non-abrasive and is not designed to remove tightly adherent rust or mill scale. It also does not create an anchor profile, so steel that needs a protective coating usually requires blasting or an impact tool such as the Bristle Blaster® afterwards.

Is dry ice blasting safe?

It avoids toxic blast media and chemicals, but it has real hazards. Dry ice is about −78 °C and can cause cold burns; sublimating CO2 can build up to dangerous levels in poorly ventilated or confined areas; and machines can reach around 120 dB(A). Ventilation, gas monitoring where needed, and hearing and hand protection are required.

Does dry ice blasting create a surface profile for coating?

No. Dry ice blasting is non-abrasive and leaves the substrate texture essentially unchanged. Coatings that need an anchor profile require a method that roughens the steel, such as abrasive blasting or bristle blasting, which produces a 65–85 µm Rz profile on standard steel in documented tests.

What is dry ice blasting used for?

It is mainly used for industrial cleaning: removing grease, oil, production residues, release agents and some coatings from moulds, machinery, electrical equipment and production lines, often without dismantling. It suits jobs where water, chemicals or abrasive residue are unwelcome and the substrate must not be damaged.