The Science Behind Dry Ice Blasting: Sublimation Explained

Sublimation powers the entire dry ice blasting process. This scientific phenomenon occurs when a solid transforms directly into gas without becoming liquid first. Understanding how sublimation works explains why dry ice cleans so effectively and why it leaves surfaces completely dry.

What Happens During Sublimation

Water provides a familiar example of typical phase changes. When you heat ice, it melts into liquid water. Heat that water further and it evaporates into steam. Carbon dioxide behaves differently. Solid carbon dioxide, which we call dry ice, never becomes liquid at normal atmospheric pressure. When dry ice warms up or gets struck during blasting, it transforms straight from solid to gas. The pellets hit the surface, do their cleaning work, and immediately convert to carbon dioxide gas that disperses into the air. No liquid means no mess, no residue, and no drying time.

How Dry Ice Removes Contamination

Three forces work together when dry ice pellets hit a dirty surface. The pellets travel fast enough to physically knock contamination loose through impact. The extreme cold of the pellets, negative 109 degrees Fahrenheit, causes thermal shock that makes contaminants brittle and easier to break. Oils that were sticky become hard. Flexible coatings turn rigid and crack. The third force comes from the expansion that happens during sublimation. Each pellet grows to about 800 times its original size as it converts to gas. This rapid expansion creates tiny pressure bursts underneath contamination layers, helping push them off the surface.

Temperature Makes the Difference

The colder the dry ice and the warmer the surface, the stronger the cleaning action becomes. A 120-degree temperature difference between room temperature equipment and the dry ice pellets creates powerful thermal shock. Contaminants shrink and lose their grip on the surface. Warm equipment cleans even better because the temperature gap is wider. This explains why dry ice works well on machinery that’s still warm from production. The thermal shock is more dramatic, which breaks contamination free faster.

Different Materials React Differently

Paint and carbon buildup crack easily under thermal shock because they’re naturally brittle. Oils and greases turn solid when they get cold, which makes them simple to chip away. Rubber-like substances become stiff and shatter. Each type of contamination responds to the extreme cold in ways that help remove it. The surface underneath matters too. Metal stays relatively warm during blasting because it conducts heat well. Plastic and fiberglass don’t conduct heat as effectively, so they can get too cold if operators aren’t careful. Experienced operators adjust their technique based on what they’re cleaning and what it’s attached to.

Pressure Waves Do Hidden Work

When each pellet sublimates, it creates a brief pressure pulse as the expanding gas pushes outward. Thousands of pellets hitting per second means thousands of these tiny pressure waves working underneath contamination. The effect acts like microscopic wedges separating dirt from the surface. This mechanism cleans textured surfaces and tight spaces where impact alone wouldn’t reach effectively. The gas expands into grooves, threads, and porous materials to lift out embedded contamination.

Putting Science Into Practice

Operators who understand sublimation can adjust their approach for better results. Heavy contamination needs time for thermal shock to weaken its bond before impact breaks it free. Delicate components require gentler pressure settings that rely more on cold and gas expansion than brute force. Distance from the nozzle to the surface changes how much the pellets have sublimated before impact, which affects cleaning intensity. These adjustments turn dry ice blasting from simple spraying into precise contamination removal. nexAir helps facilities apply this science to their specific cleaning challenges. Our team brings technical knowledge and hands-on experience that turns theory into working solutions. With nexAir’s KnowHow™, operations can Forge Forward using cleaning methods grounded in solid science and proven results.