Dry ice is an unusual and fascinating substance, used for everything from creating visual effects in movies to keeping perishable goods frozen during shipping. Its unique properties make it a useful addition to many kitchens, but before you can use it, it must be stored correctly. The best method for storing dry ice long term is in an insulated cooler or Styrofoam box, with a loose lid that allows the gas to escape. This prevents direct contact between the ice and the items in the container, and it also maintains a consistent low temperature.
The most important thing to remember when how to store dry ice long term is that it is not actually ice but carbon dioxide gas. It evaporates into this gas at a much lower temperature than air, so it must be kept in an environment that is as cold as possible to prolong its life. This means storing it in a Styrofoam box or an insulated cooler, not a freezer, as the latter is too warm for dry ice. The ice will melt into gas in the freezer, causing it to lose its cooling effect, and it can also damage the unit itself.
A specialized dry ice storage container is also available, which maintains the subzero temperature of the ice for longer and provides optimal insulation. However, for a simple and affordable solution, a plastic or Styrofoam box can be used to great effect. The key is to choose a container that is large enough for the amount of ice you are planning on using, and then to wrap it with newspaper or other material to provide additional insulation. A loose lid should be used, as an airtight seal would reduce the effectiveness of the insulating materials.
Avoid opening the container frequently, as this causes warm air to enter and accelerate the evaporation of the ice into gas. The cooler or box should be placed in a cool, well-ventilated location, such as a shady spot outdoors. If the container is to be transported, it can be pre-chilled by placing other ice or ice packs in the cooler.
A block of five pounds of dry ice will last about 24 hours before it completely evaporates into a gas. This is why it is best to buy it just before you need it, for example, at a grocery store when buying Halloween supplies. If you purchase it too early, it will not have enough time to sublimate into a gas before your event or party. You can also buy it from specialty shops, but it will likely be more expensive and come in a smaller size than you might want to use. If you are going to make a purchase like this, be sure to check online reviews to ensure that the company you are dealing with will be able to deliver on their promises. This is an essential part of purchasing any product, so it is worth the extra research to find a reputable seller.