If you’re a party animal, then you know there is nothing cooler than sipping cocktails with dry ice in them. Dry ice is a common term for a solid block of carbon dioxide. What makes this substance different from regular ice is that it doesn’t melt into liquid but evaporates into a gas. This process is known as sublimation and is what makes dry ice produce that cool, ghostly steam that takes your drink to the next level.
Though the substance is frozen at extreme temperatures, that doesn’t mean it’s resistant to melting. A block of dry ice sublimates much faster than regular ice, especially if you store it improperly. Therefore, if you’re wondering, “how long does dry ice last”, stick around for a complete breakdown of this substance and how you can extend its shelf life.
How Long Does Dry Ice Last?
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As established, dry ice is a solid form of CO2 or carbon dioxide. Manufacturers make it by compressing the gas and then freezing it using extremely low temperatures. This process produces a liquid form of CO2. Manufacturers then take the liquid and press it using hydraulic presses into solid blocks, pellets, or ice slices.
The temperatures required to produce dry ice are much lower than those needed for regular ice. Most dry ice blocks have a density of around 1.56g/cm3 and a maximum temperature of -78.64°C or 109.55°F. With this staggering internal temp, you’d think that dry ice would melt much slower than regular ice. However, the opposite is true.
Dry ice sublimates much more quickly than regular ice. Overall, you will lose between 5 to 10 lbs of dry ice over 24 hours. Now, this meeting time isn’t exact, and it largely depends on how you store your block.
1. In a Cooler
Predictably, using a cooler to store dry ice will slow down sublimation. However, exactly what shelf life you’re looking at depends on two factors — the cooler size and the amount of dry ice you use.
A general rule of thumb is that the smaller the cooler is, the longer the ice will last. So, for example, if you store 10 pounds of dry ice in a 25-quart cooler, you’re looking at a 24h-sublimation time. But, if you pack an extra 5 pounds of ice in the cooler, you could extend the ice’s shelf life for an additional 4 hours. This is because extra dry ice reduces the temperature further. Plus, the confined space traps the gas, making it harder to evaporate.
2. Outside
Dry ice is notoriously sensitive to temperature fluctuations. Therefore, leaving it out in the open at room temp dramatically speeds up sublimation time. On average, a 5-pound brick will last anywhere between 3 to 5 hours when left outside. This, of course, will largely depend on where you leave the block and how hot your environment is.
For instance, a block of dry ice will sublimate in just 2 hours if you leave it in direct sunlight. Likewise, dunking dry ice in any kind of liquid will dramatically speed up melting. A 5 lb block can evaporate in just 15 to 45 minutes, depending on the amount of liquid you use to store it.
How Do You Keep Dry Ice From Melting?
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If you’re hosting a wicked Halloween party, then your top priority is keeping your dry ice from evaporating too quickly. Fortunately, there are several ways to do this.
Firstly, be sure to store it in an insulated cooler with a partially cracked lid. As mentioned, dry ice is frozen CO2 that evaporates into a gas. Therefore storing it in an airtight container with no vent for the gas to escape can cause your container to explode, potentially leading to an injury.
Secondly, be sure to avoid exposing the ice to direct sunlight or high temperatures. Obviously, this will cause your block to sublimate more quickly. Only keep your dry ice in the shade or a cooler, well-aerated area of your home if you intend to leave it out at room temp.
Lastly, time your order. No matter what technique you employ — to get the most out of your block, place your order in advance and pick it up an hour or two before your party is set to begin.
3 Storing Tips
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In case you’re currently faced with an order of dry ice you don’t know how to store, start taking notes — these fool-proof storing tips will help you extend your ice’s shelf life two-fold!
1. Pack It in a Smaller Cooler
In the case of dry ice, bigger is not better. Packing your dry ice pellets in larger storage containers will make them sublimate faster. So, to avoid this, use smaller ones. If you only have a larger one lying around, line it with insulating materials like styrofoam or newspapers. This will help pack the ice tighter and trap the cold around it.
2. Handle With Care!
As you can expect from something with an internal temperature well below freezing, dry ice is dangerous to handle. Direct contact with a block of dry ice can result in some pretty severe frostbite. Therefore, you should never pick it up using bare hands. When handling a block of ice, only use cryogenic gloves and protective goggles.
3. Don’t Leave It in a Walk-in Freezer
As tempting as it is to keep dry ice in a walk-in freezer, this is ill-advised. CO2 is one and a half times heavier than oxygen. Therefore, it can easily displace the molecule in confined spaces. So, even a small amount of dry ice that sublimates too quickly in a poorly ventilated walk-in freezer can produce a buildup of CO2. High concentrations of carbon dioxide are extremely dangerous to human health and can cause suffocation, dizziness, and nausea.