july2017

44 45 COLD JET, LLC “Dry ice is not aggressive enough to do that on its own, so they never really developed it into a big commercial system,” Marlowe ex- plains. “However, there are a number of industri- al cleaning applications that it works really well on. So, in the mid-‘80s, an investment group got together in southern California and licensed the patents from Lockheed. They had developed a two-hose, venturi-style, dry ice blasting sys- tem. About the same time, Cold Jet started in Louisville, Kentucky. They had a different tech- nology for dry ice blasting with a single hose, or a positive feed system, which required an air lock–basically, it mixed the dry ice particles with compressed air, rather than a vacuum tube pulling it down and mixing it at the applicator. It turns out that the single hose that Cold Jet developed is actually the better technology because you can achieve higher velocity with the particles, which in turn, means that you can clean faster and more powerfully. In 2003, Cold Jet ended up buying Alpheus, the company in California that licensed the patents from Lock- heed. So, the history really starts in the mid-‘80s for developing dry ice blasting for a number of commercial cleaning applications.” Marlowe breaks down the dry ice blasting process: “In concept, it’s sort of like sand blast- ing, but the effect is quite different.We propel particles with compressed air, but the particles we use are particles of dry ice. They hit the surface and there is some impact energy that does a lot of the cleaning. There are a couple of different formats - we can use three-millimeter pellets of dry ice that looks like rice.We can also take a block of dry ice and shave it, and you get a sugar-sized particle. The reason you’d want to do that is because smaller particles have less chance of damaging the substrate and you can do more precise cleaning because smaller particles fit into smaller gaps and vents of the different things that you’re cleaning. The particle size on the shaved dry ice is some- where between 0.0 and 0.3 millimeters; so it’s quite a lot smaller. “And dry ice has some other characteristics that other blast media do not have: dry ice is very cold so it cools the contaminants faster than the substrate, so they shrink and dis-bond. Also, as the particles hit a surface, they subli- mate on impact, going from a solid to a gas, which means they disappear. There’s no sec- ondary waste. If I clean with water, or sand, or