When it comes to keeping food and drinks cool, thermal bags can be a real lifesaver. These bags have an extra layer of insulation that makes them better than non-thermal bags. They also stay cool for a long time, making them ideal for summer travel.
If you’re in the market for a new cooler bag, you’re probably wondering – how long will the cooler keeps food refrigerated? In today’s guide, I’m going to tell you all about thermal bags, how long they can keep food cold, how to use them, and how to keep them cool longer.
Table of Contents
How Thermal Bags Work
The thermal bag uses reflective and insulating materials to keep cold food tasty and cool. Reflective materials, such as aluminum, reflect thermal radiation, keeping cold (or hot) air trapped inside. They also use insulation (usually foam, but sometimes paper or plastic) to stop the heat from escaping.
They are not as powerful as hard surface coolers (eg rotary molded coolers), but they do have the advantage of being lightweight and portable which makes them ideal for certain situations such as day trips, golf bag coolers, or lunch coolers for construction workers.
How Long Can Thermal Bags Keep Food Cold?
Of course, this answer depends on a few variables – how hot you are, the amount of insulation in the thermal bag itself, etc. So any answer you find will be a rough approximation.
Using ice cubes or ice packs, the thermal bag can stay cool for up to 12 hours. The weather will gradually get warmer, which means that if there is anything in the bag that needs to be refrigerated (, needs to be eaten quickly.
If your lunch thermal bag sits for a long time, it may heat up. Once the temperature rises, the food inside can only be eaten for 2 hours.
So, in essence, pack as many reusable ice packs as possible in your thermal bag to keep things as cold as possible and eat your perishables quickly.
In terms of keeping drinks cool, you should still expect to have a cold drink at the end of your day’s trip (depending on the quality of the thermal bag you choose), although a cold drink may end the day a little warmer than it started.
Sometimes you will see the ice retention time in the product description of the heat pack. This refers to how long the thermal bag can hold the ice before it melts. These measurements can be used as an approximate reference, as tests are often performed under ideal conditions. For example, if you use it outdoors or in hot weather, you may find that the ice melts faster than the stated time.
Should I Use Ice or Ice Packs for Thermal Bags?
A better option for a heat pack is to install an ice pack between the ice and the ice pack. Ice will melt and mess up the thermal bag, and ice packs can’t do that. They stay cool longer but are usually small, so you’ll have to replace them often.
The great thing about ice packs is that you get reusable packs that you can use whenever you want. So, if you’re planning to travel in the sweltering heat, consider getting some extra ice packs.
How to Keep a Thermal Bag Cold for the Longest Period of Time?
As mentioned, the heat pack will stay cool for about 12 hours. Times may vary by situation. There are things to shorten the time, but there are also things to keep the thermal bag cooler for longer. Let’s focus on the latter question and see what you can do to keep the heat pack cool for longer.
Frozen water bottle
If you have room in your thermal bag, consider adding a chilled water bottle. This will help the whole thermal bag stay cool for a long time as the ice water takes hours to thaw. During this time, it will help keep everything around you cool.
The only thing you need to do is use a regular bottle, fill it with water, and put it in the fridge for at least a few hours before heading out. Take the bottle out of the refrigerator immediately before traveling.
Frozen food
If your thermal bag isn’t that big, you can choose to use frozen food instead of a frozen water bottle. Find the type of food you want to eat and consider which foods can be frozen beforehand. Keep food in the refrigerator until the day of travel, then put it in a thermal bag before you leave home.
If you can’t freeze food, consider taking it out of the freezer and wrapping it in aluminum foil. Like foil on a hot pack, foil on food helps it stay cool longer.
This is another great option as you’ll be eating food and emptying thermal bags on the go. By the end of the trip, you will be much lighter than initially, which is another great thing!
Perfect location
While there are things you can do inside the thermal bag, there are also things you can do outside the bag to keep it cool. I mentioned earlier that you need to keep the thermal bag in direct sunlight. You can place it under a larger rock or a tree, or wherever you find it cool.
If you live in a cabin or similar, consider placing the thermal bag in the shade or under an air conditioner. These are all things you can do to keep the thermal bag colder and longer.
Do not open it!
Finally, pay attention to how many times you open the thermal bag while traveling. If it’s hot and you keep opening it, you’ll let hot air into the thermal bag. This will make the thermal bag warmer, which will warm everything inside. So, unless you need to get something out of the thermal bag, you shouldn’t open the thermal bag!
Summary
We hope this helps answer the question of how long the thermal bag will keep food. It’s hard to give a definitive answer as there are so many variables, but hopefully, you can use some of these tips to keep your lunch or drink cool throughout the day.
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