I recently returned to the gym and partly due to my over enthusiasm, I have come down with a nice case of shin splints. Part of the treatment is to ice my shins three times a day for twenty minutes. I decided to test a trick I had stumbled across several times in the past.
Fill a 1 qt freezer bag with ice cubes and add approximately 1/4 cup isopropyl alcohol. Don’t worry about measuring, just eyeball it. Use and refreeze as necessary. I wrap the bags in a kitchen towel to keep the condensation from dripping onto my clothing. So far they work perfectly and are wonderfully cold.
Remember to only use these under adult supervision as small children may be tempted to chew on the ice pack.
*Edited to add* The alcohol lowers the freezing point of the water. When you toss the ice melts it mixes with the alcohol. When the water and alcohol mixture is placed back in the freezer it becomes a very cold slush rather than a solid block of ice.