Mix 2 parts water to 1 part rubbing alcohol in a large Ziploc freezer bag. Keep this in your freezer and it will become slushy. You may re-use pack again by refreezing it. When ready to use, wrap a moist warm towel around cold pack and place it directly on your skin of the affected area. Leave on for 10-15 minutes or until your skin gets numb. Consult with your therapist or health care professional before using a cold pack for a particular condition or injury.