The Sponge Ice Pack Actually Works

A wet sponge in a zip-top bag is the best homemade reusable ice pack for a lunch box.

All you do is soak a clean sponge in water, squeeze out the excess so it’s damp but not dripping, then slide it into a freezer bag. Freeze it flat. That’s it. It freezes into a thin, flexible-ish pack that fits around a sandwich instead of fighting with it like a hard block of ice.

The sponge matters because it holds the water in place. No sloshing, no big ice brick forming in the corner of the bag, and if the bag ever leaks, you get a damp sponge, not a puddle of water in the lunch box. Double-bag it if you’re paranoid. Works every time, and you can just toss it back in the freezer overnight.

One warning: use a fresh sponge that you only use for this. Old kitchen sponges hold bacteria. And if the pack sweats when you take it out, wrap it in a paper towel before it goes next to food.

Future ice packs are three dollars. But this one is free.