How To Make Dry Ice Last Longer

Dry ice is no longer a mystery ingredient exclusive to food packing companies and chemistry class demonstrations. You can order it online or even find it at grocery stores, and it's a serious boon for keeping ice cream frozen in a cooler and even protecting perishable foods from summer power outages. However, before you grab a package, you still need to learn how to safely handle dry ice and store it properly.

First of all, dry ice — which is just frozen carbon dioxide – should never be stored in your freezer alongside your ice cream and bags of peas. It has a temperature of -109 degrees Fahrenheit, making it way colder than regular ice, and it has to be kept at this temp or below in order to stay solid. In warmer environments, dry ice dissipates into gas instead of melting into a liquid, creating that characteristic "smoky" effect. Home freezers should be kept at zero degrees Fahrenheit, so not only are they too warm to make your dry ice last, but sticking a block in there is downright dangerous.

Dry ice is so cold that it can easily shut off or break your freezer, and if you put it in an airtight container first, the CO2 gas will build up pressure inside and cause it to explode. To make sure your dry ice is both long-lasting and safe to handle, it should be stored in an insulated cooler — preferably styrofoam — with the lid cracked open a bit.

Dry ice keeps food frozen for way longer than regular ice, but if left out at room temperature or warmer, the blocks will dissolve in less than five hours. Both styrofoam and insulated coolers make a good home for dry ice — the thicker the insulation, the longer it will stay solid. Keep the cooler in a well-ventilated room to avoid CO2 buildup, which can replace oxygen in the air and make it hard to breathe. If you're taking your cooler on a long drive or you're transporting dry ice from the store, roll down the windows in your car.

How long your dry ice lasts depends on the size of the blocks, plus the exact temperatures inside and outside the cooler. Five to 10 pounds of dry ice will last for 24 hours in ideal conditions, so if you want your supply to keep for days, you'll need to store more blocks together. To help dry ice last longer, keep the container in a cool, shady area out of direct sunlight, and try not to fully open the lid over and over. Air exposure naturally warms up the ice.

If you have any chunks left over after your cookout or Halloween party, never put dry ice in the sink or in a trash can, as it will end up causing an explosion. You should simply let the blocks dissipate outside instead. And of course, never let the substance touch your skin, and wear protective gear while handling it.