I have a single, lonely blue ice pack in my freezer. Smart move: last weekend I was planning a day at the park with my friends and I realized (on the day of) that I only had one ice pack to work with. So I went online to see what I could possibly do to make my own ice pack with two or three hours to spare. Luckily, I had just the thing: dishwashing sponges.

I know I can freeze a tub of water to make a giant ice cube, or melt a bunch of water bottles into a refreshing drink, and those are good options. However, I didn’t have time and I had about a mile to walk to the park, so I wanted to pack light.

Sponges are cheap, so you can buy a few. They’re small and hold most of the water even after they’ve been heated, so they’re great for lunch boxes and small spaces. They’re lightweight, and they serve another purpose. So if you’re an occasional cooler user like me, you can come home from the park, squeeze out the sponges, and use them to wash dishes. Now you have your freezer back. And if something spills during the picnic, you’re kind of a hero.

Start with clean sponges. They don’t necessarily have to be new, but freezing old, used sponges seems somehow disconcerting to me. I think it makes more sense to use new sponges as ice packs and then move them on to their next life stage as dishwashing sponges rather than the other way around.