Should  you stack your Cooler Shock ice packs when freezing? Not if you need them soon!

How to Freeze Cooler Shock Ice Packs

This blog is sometimes about things that I should have covered years ago. What often happens is I have this revelation when I realize something that is obvious to me (because I invent ice packs), is not so obvious to my customers.

This blog is about stacking ice packs and how that can be good or bad.

Cooler Shock ice packs can absorb a great deal of energy (heat). To do this, they must have a lot of mass (similar to weight). The greater the mass, the harder it is to change its temperature and the longer it will take.


The temperature of the ice packs is changed through the surface area of the ice packs. Either heat or cold is applied to the surface for it to be cooled down or to absorb heat. So, here’s the thing, if you stack our ice packs in a freezer, the ones in the middle will be insulated from the cold air (since no surface area is exposed) and take an extra-long time to freeze.

We once had a customer call us to tell us that he had defective ice packs. The complaint was that he had some packs that would not freeze after two days. With a bit more questioning we were able to fix his ice packs by recommending that he not stack them in the freezer if he planned on using them soon!

The overall idea here is when you freeze your packs, distribute them so they have as much exposure as possible on both sides. You will be much happier!  Alternatively, you might really like the mesh carry bags that we sell. A feature of the bags is that it reduces the stacking effect by creating an air space between the packs when they are stacked.

So, what’s the positive to stacking packs?

If you are going on a long trip and want your ice packs to last a long time in your cooler, use the right amount to get the job done and stack the rest. As the exposed Cooler Shock ice packs (the ones that are not stacked) start to soften, expose additional ice packs from your stack. You will find that the ones in the middle will stay like new for days. In this way, you can use Cooler Shock ice packs for many days to keep your items fresh and cold.