Dry ice is extremely cold and at -109.3°F (-78.5°C) it sublimates and turns from ice into gas pretty quickly at room temperature. So how can you make dry ice last longer so you get to take advantage of it's cooling effects for a longer period of time?
If you're going to go out there and spend the time and the money buying dry ice it makes sense to work out how to make it last as long as possible.
Given the right preparation and the right conditions dry ice can last for days and keep things frozen for days or even weeks at a time.
Below are my 14 top tips for keeping dry ice for longer. Ideally combine as many of these ideas as possible to keep your dry ice for as long as possible.
1. Use a Dry-Ice Compatible Cooler
The best way to store dry ice is in a cooler. You first need to make sure that your cooler is dry-ice compatible.
Most hard sided coolers ranging from cheap styrofoam coolers to expensive coolers like Yeti are dry ice compatible.
Be careful with soft sided coolers as the plastic lining used in these is not designed for the extremely low temperatures of dry ice. This will cause the lining to break and will damage your cooler.
So stick to plastic coolers or styrofoam coolers and avoid soft-sided coolers with soft plastic linings.
2. Use an Expensive Cooler
Expensive roto-molded coolers like Yeti do keep dry ice for much longer than a cheap plastic cooler you might pick up from your local Walmart or supermarket.
While a cheap cooler might only keep your dry ice for 12-24 hours an expensive cooler can keep that same dry ice frozen for 2-3 days.
If you use larger quantities and larger blocks of dry ice then you can keep it for even longer. With the right cooler and enough dry ice you can keep dry ice frozen for over a week!
Expensive coolers use a more effective polyurethane insulation as well as a thicker plastic in the inner and outer walls.
Expensive coolers also has thick insulation in the lid (cheap coolers don't have insulation in the lid) and they have rubber gaskets to keep most of the cold air locked in. You do want to make sure there is room for the gas from the dry ice to vent though.
Price isn't everything and there are a lot of different brands out there. Some can hold ice and dry ice much longer than others.
I've written a full article on the best coolers for holding ice the longest if you want to see the full list, but below are the top 3 coolers for keeping ice the longest:
Yeti V Series
The Yeti V series takes the serious insulating power found in vacuum insulated cups and bottles like Hydro Flask and adds it into a cooler.
It uses a combination of vacuum insulation and high quality foam insulation to keep ice 50% longer than regular Yeti coolers and longer than any other cooler on the market.
It also happens to be the most expensive cooler on the market.
Kong Coolers are another newer brand that shows amazing ice retention performance. They are dry ice compatible, made in the USA and come with some great features that other coolers don't have.
3. Wrap Your Dry Ice In Newspaper, Cardboard or a Towel
When dry ice is exposed to the air the warm air will cause the dry ice to turn to a gas quicker than if you keep it out of the air.
Newspaper, cardboard and towels are all insulators themselves.
By wrapping up your dry ice in one of these items you're adding a layer of insulation to your dry ice and you're also stopping the air flowing directly over the dry ice which will make it disappear faster.
It also helps to protect yourself as well as your food and drinks from the extreme cold of dry ice which is so cold it can cause frostbite if you're not careful.
4. Pre-Chill Your Cooler
This is one of the biggest tips for keeping ice longer in your cooler and it is especially true for dry ice.
Coolers, especially thick expensive coolers like Yeti, are great at insulating and keeping things cold. However, if left at room temperature or in a hot room then then insulation can actually absorb a lot of heat.
If you put your dry ice into a cooler that is warm then a lot of the dry ice will be used just to cool down the insulation in the cooler. This will give you terrible ice retention performance (worse than that of a cheap cooler).
To avoid this use a sacrificial bag of ice or some frozen water bottles and place them in your cooler the night before. Or for even better results take a bit of dry ice and put it in your cooler the night before to cool the cooler right down.
Putting your dry ice in a cooler that is already cold will make it last much much longer.
5. Use More Dry Ice
The larger the quantity of dry ice you use the longer your dry ice will last overall.
It takes a lot of heat energy to melt dry ice. If you only have a little bit then not much heat is needed to make it all turn to gas.
However, if you have a lot of dry ice this does two things.
- It requires more overall heat to completely sublimate all of the dry ice
- When paced together the dry ice in the middle is actually insulated from the outside air by the dry ice on the outside.
This extra quantity and extra insulation means you can get days or even a week or more out of your dry ice. Click here to learn how much dry ice you should use in a cooler.
6. Use Larger Blocks of Dry Ice
Larger blocks of dry ice will last longer than the same amount of dry ice but it loose smaller blocks.
The large blocks have less surface area which makes them sublimate slower and the inside of the large blocks are insulated by the outside of the block. The warn air can't reach it to even try and melt it until it's melted the outside of the block.
7. Keep It Out of Water
Water has a much great heat capacity than air and it can convect or move heat around much quick and more effectively than air.
Putting dry ice in water will make it sublimate at a much faster rate than air, even if you feel like the water is colder than the outside air.
8. Pre-Chill or Pre-Freeze Your Items
Putting room temperature food or drinks into a cooler with dry ice adds a lot of heat into the cooler.
Your dry ice will then get used up bringing those food or drink items down to freezing temperatures. This will cause your dry ice to disappear faster.
To make your dry ice last longer pre-freeze any food or drinks you can and pre-chill everything else.
This adds less heat into your cooler so your dry ice doesn't have to do as much work to cool them down. This will make your dry ice last a lot longer.
9. Minimize Air Space
The more air space in your cooler the quicker the dry ice will melt. I found this out when I was doing research into which coolers keep ice the longest.
When the same amount of ice (or in this case dry ice) is used then a smaller cooler with less internal air will preform better and keep the dry ice longer than a large cooler with a lot of internal air.
So use a smaller (but still high quality) cooler where possible or if that isn't possible then fill up the excess space with something insulating like styrofoam or even crumpled up newspaper.
10. Put It At The Bottom Of Your Cooler
Cold air sinks and hot air rises. Warm air also enters your cooler from the top when you open the lid.
Putting your dry ice at the bottom of your cooler instead of at the top will make it last longer.
11. Keep It Out of Direct Sunlight
Putting your dry ice or your cooler in direct sunlight adds a lot of overall heat, which eventually causes your dry ice to disappear faster.
Keep your cooler in a cool shady spot out of direct sunlight and it will last longer.
12. Don't Put It In The Freezer
It might sound like a good idea to put dry ice in the freezer given that a freezer is already kept at the low temperature of 0°F (-18°C). This is much colder than the outside air so your dry ice should last longer right?
Wrong, kind of.
The dry ice is so cold that it will cause the thermostat in your freezer to read that your freezer is too cold. This will cause your freezer to turn off to save power.
So putting dry ice in a freezer causes the freezer to turn off and the dry ice to do all of the cooling work. There's also lots of air in a freezer which can cause it to sublimate faster.
There's also the chance you may cause damage to your freezer and break it so it's not worth the risk. Read more about whether or not you can put dry ice in a freezer here.
13. Combine With Ice or Ice Packs
Combine your dry ice with regular ice or ice packs. These will act to insulate the dry ice from the outside air, but it also means that once your dry ice is all gone the regular ice or ice packs will still be frozen and will keep your food or drinks colder for longer.
14. Line Your Cooler With Aluminium Foil
Aluminium foil is amazing at reflecting heat radiation, which is something most coolers aren't designed to reflect.
By lining your cooler with aluminium foil you are adding a further level of insulation to your cooler against this heat radiation and that will help your dry ice to stay frozen for longer.
Important Considerations When Using Dry Ice
Always be careful when using dry ice. While it isn't particularly dangerous when used correctly if you aren't careful it can hurt you and dry ice can even kill you in rare circumstances.
Don't Completely Seal It
Dry ice doesn't melt (turn from solid into liquid) it sublimates (turns from liquid directly into a gas).
This creates a. lot of carbon dioxide gas which expands a lot compared to the frozen block of dry ice.
Make sure you have a way for this gas to escape from your cooler. Also make sure if you're driving with dry ice you have your windows down and lots of ventilation.
Don't Touch It With Your Bare Hands
Dry ice is so cold that it can cause frostbite in as little as a couple of seconds if it is touching your bare skin.
So always use protective clothes or something else insulating when handling dry ice so you don't get burned.
Don't Put Food Directly Onto Dry Ice
Dry ice is so cold that it can cause freezer burn to occur on some food, ruining it's taste and texture.
Wrap your dry ice in newspaper, cardboard or a towel first before putting your food in your cooler.
Don't Use Dry Ice With Drinks/Soda
Dry ice will cause drinks to completely freeze. If you put soda in a cooler with dry ice then it will freeze and the build up of pressure can cause the bottles to explode.