By Ryan Taylor, Nitrofreeze Cryogenic Solutions
Dry ice blasting is used in a wide range of historic restoration projects, including a recent one completed in Rockport, Mass., in July of this year. Nitrofreeze Cryogenic Solutions was contracted to dry ice blast barn board wood inside a fishing hut to lighten the surfaces and bring them closer to their original state.
Originally, the fishing hut was only a small wooden enclosure, but it will now be preserved since a fully functional house has been built around it, acting as a protective shell. This new home was completed within the last year. The fishing hut itself dates back to the early 1700s and has been exposed to environmental contaminants for nearly 300 years. Over time, this exposure caused the wood surfaces to darken significantly.
The Nitrofreeze team used dry ice blasting technology to remove a thin layer of wood, lightening the substrate and restoring its appearance to something closer to its original look from three centuries ago. Dry ice blasting is a non-toxic and non-abrasive cleaning process that uses solid carbon dioxide pellets and compressed air. The pellets are propelled at high speed and directed at the substrate — in this case, the barn board. When the pellets hit the surface, they almost immediately sublimate into carbon dioxide gas. Some of the kinetic energy transfers to the surface, removing a thin layer of wood. The minimal abrasion depends on the thermal conductivity of the surface being blasted.
Compared to other blasting techniques such as soda blasting, sandblasting or chemical treatments, dry ice blasting is completely non-toxic and non-conductive since dry ice is inert. The only waste produced is the fine layer of wood removed during the process.
The effectiveness of dry ice blasting is rooted in cryogenic science. Dry ice is the solid form of carbon dioxide and exists at a temperature of -109.3°F (-78.5°C). When these extremely cold pellets strike a surface, they cause a rapid temperature drop that creates thermal shock. In the case of historic wood, this shock causes surface contaminants to contract and loosen, making them easier to remove without damaging the underlying material.
As the dry ice pellets make contact, they sublimate instantly, changing directly from solid to gas. This phase change is critical because it expands nearly 800 times in volume, creating a gentle lifting effect that helps separate layers of dirt, paint, or buildup from the surface. Unlike abrasive blasting methods that grind away material, the cryogenic properties of dry ice allow for precise cleaning with minimal surface wear.
Because the process uses frozen carbon dioxide, there is no secondary waste stream such as water or chemical residue. This makes it especially valuable for conservation and preservation projects where maintaining the integrity of the original structure is essential. By leveraging cryogenic principles, Nitrofreeze is able to clean centuries-old materials safely, efficiently, and in an environmentally responsible way.
For this project, Nitrofreeze used a fragmenting nozzle on the dry ice blaster and passed about two pounds of ice pellets per minute through it to maintain a minimal amount of abrasion on the wood surface. This careful approach helped protect the fishing hut from further damage while achieving the desired cleaning effect. The work required blasting all wood surfaces inside the hut, including the walls, ceiling, beams, and posts.
Dry ice blasting is a versatile tool with many applications in restoration work. Nitrofreeze also recently completed a project at the Museum of Fine Arts in Boston, supporting preservation efforts for several statues. While that project involved metal substrates, dry ice blasting can also clean many building materials, including stone, brick and a variety of wood types.
The restoration in Rockport was a success, and the customer was thrilled with the results. Dry ice blasting effectively removed layers of environmental buildup that had accumulated over the course of nearly 300 years. Nitrofreeze uses these same processes in a wide range of industries, from industrial manufacturing to food and beverage, to historical preservation. Nitrofreeze is committed to exceeding customer expectations while maintaining strict environmental standards. The company has provided dry ice blasting services in the New England area for nearly 20 years. http://www.nitrofreeze.com
