Here's a formula for some of the coldest Bait cooler ice packs you can make for your cooler. They are sub freezing (13 F in tests) and stay below freezing for up to 24 hours! I initially started the experimentation to find something that would keep my bait cold as long as possible. Seeing the results, I am comfortable saying that you could use these for picnics, drinks, whatever you need to keep super cold for long periods of time! One last note, make sure your freezer is as cold as possible. The ice packs will only get as cold as your freezer can get them.
You can read the full article here:
https://extremediy.org/super-cold-long-lasting-cooler-diy-ice-packs/
