Freezer-Pack Ingredients

Instant Cold-Packs

• Instant cold packs are disposable and don't need to be frozen before use. They are often used in first aid kits to provide temporary relief for minor burns, sprains or contusions. Active ingredients are kept in separate compartments. When the ice pack is cracked the active ingredients, ammonium nitrate and water, combine to create a cooling effect. Reusable instant cold packs that can be frozen after the initial use are also available. These freezer-packs use similar technology, including a polymer gel that can be frozen for re-use.

Instant Cold-Pack Chemistry

• Instant cold packs consist of two compartments, one with ammonium nitrate crystals and the other with water, or a water-based gel. When the pack is squeezed the barrier between the crystals and water breaks, mixing the components together and creating an endothermic reaction. In an endothermic reaction, heat is absorbed creating a cooling effect. Essentially, the ammonium nitrate steals energy from the water, making it colder than it was before they were mixed.

Gel Freezer-Pack

• Gel-freezer packs are reusable and are often used in homes for basic first aid. Gel freezer-packs are used to treat headaches, minor burns, sprains and contusions. They can also be added to coolers or sack lunches to keep food and beverages cool. These packs include a colored, non-toxic polymer gel. At least one manufacturer uses CMC-based polymer gel. CMC, or carboxymethylcellulose, is used as a thickening agent in foods and gel products.

Homemade Gel Freezer-Pack

• If you are concerned about the safety of the ingredients in freezer-packs, you can make your own at home. Mix 2 cups of water with 1 cup rubbing alcohol in a re-usable plastic bag. Place that bag in a second re-usable plastic bag and freeze for at least 24 hours. The resulting slush is excellent for treating minor burns, sprains and bruises.