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In this article, we’re talking all about keeping lunches cool! That’s right, we’re talking about insulated lunch boxes! An insulated lunch bag is a great, convenient choice for packing a cold lunch. These products tout numerous benefits, and we’ll examine them all below. Specifically, we’re going dig deep and actually examine how these products work!

So, if you have an inquisitive mind, read on to learn more about this useful lunch cooler that’ll keep your packed lunch cool.

How-To Make a Reusable Lunch Bag

What is an “Insulated” Lunch Box?

An insulated lunch box is just what the name implies. It’s a lunch coolerbag that has extra layers of insulation to keep cold food at a certain temperature. There are several options of insulated food containerson the market, but most of them tend to follow a pretty similar design pattern. In the next section, we’ll explain how they work. Understanding how these lunch boxes work can help you to evaluate the product offerings on the market.

How Does It Work?

An insulated lunch box works by having a multi-layered design. Each layer of the lunch box (or lunch bag) serves a certain purpose. Typically, there is an outer layer, an inner layer, and a middle layer.

An insulated lunch bagor lunch container starts with a hard outer-layer. This layer is typically made of a hard plastic or vinyl material (or even stainless steel). In the case of an insulated bag, it might also be polyester or nylon. Regardless of the material, the primary function is similar, to provide a layer of rigidity and protect the lunch boxes contents from damage. In the case of a lunch box, the outer layer holds its shape quite well, and will prevent the lunch box from getting crushed when placed into a bag (such as a backpack).

There is also an inner layer. The primary purpose of the inner layer is waterproofing. The inner layer is typically made of something like plastic, aluminum, or vinyl, although other options are available as well. The waterproofing keeps any water that may run off the food (or even ice) from damaging the lunch box (or anything surrounding it). Any water would stay inside the lunch box, so that it can be easily drained. A leak-proof lunchbox is essential if you are storing your lunch box in a bag with your valuables. Of course, you probably want to minimize water regardless, as it could make your meal wet and soggy!

Then there’s the middle layer. The middle layer is the primary layer for insulation. The insulation material will vary, but often it is a foam-like substance, such as polyurethane, polyethylene, or thermal batting. Basically, this insulation material prevents heat transfer. It prevents heat and cold from escaping the lunch box, keeping your food at the desired temperature.

How Effective Is It?

It goes without saying that there are various degrees of quality when it comes to an insulated lunchbox. Numerous factors will actually influence how well it performs. These factors include: 

  • Temperature Outside:The outside temperature is one of the top variables when considering how effective an insulated lunchbox will be. It goes without saying that, if you live in a hot climate, your food will quickly heat up to room temperature You need to consider this when you’re packing lunch and when you buy your lunchbox. Hotter areas may require a more extensive lunch box! 
  • Materials: The quality of a lunch box’s design will also influence its effectiveness. The materials used, as well as how much of the materials are used, and how the lunch box is actually constructed. Materials with thicker, more durable middle linings will provide more effective insulation. 
  • Quality of the Seal: Another important variable is that actual quality of the seal on the lunchbox. The seal is found in the area where the lunchbox opens. If temperature is able to escape through this seal, then you have a lower quality insulated lunch box on your hands. For example, a Velcro seal on the lunch box is less effective than a zipper seal. 
  • Contents Within the Box: What you are actually packing for lunch makes a pretty big difference as well. For example, you probably won’t be able to get away with packing actual frozen food without expecting some melting. Insulated food containers are meant to keep food cool, but they aren’t meant to be perfect. They don’t provide total insulation, and are really only good for holding temperatures for about 3 hours (the distance from breakfast to lunchtime). So, unless you get a top-of-the-line lunchbox, you probably can’t get away with packing things like popsicles in a school lunch.

Is There Any Way to Make It Better?

Now that we’ve examined the typical properties of an insulated lunch box, is there a way to actually improve the performance of these products? Yes!There are a few ways that you can keep your food cooler (or warmer) longer!

First, if you want to keep things extra cool, try a cooling pack. An icepack or a gel pack will emit cold throughout the day, and further extend the cooling properties of the lunch box. Additionally, the lunch box will insulate the temperature emitted from the pack, so the two work together quite nicely!

Next, be sure to add some layers of “insulation” to your food as well. This insulation can be as simple as plastic wrap for a sandwich, or keeping your food in a Ziploc bag. This simply provides yet another layer to keep the temperature locked in!

And finally, don’t open the bag! Every time you open the bag, you let a lot of the inner temperature escape. Everything that was efficiently being insulated escapes the bag, and a lot of the efficiency is lost. Definitely keep your bag closed until you need to use it!

Definitely keep your bag closed until you need to use it


Thanks so much for checking out our guide to insulated lunch boxes! Hopefully we’ve given you some useful tips and tricks for buying your next lunch box, and keeping your food cool or warm until it’s time for lunch!