Obviously, the best place to keep an ice cube from melting is the freezer. However, it is sometimes necessary to transfer ice from one place to another when lugging your freezer with you is not an option. There are certain materials that can be used to insulate ice that work better than others at keeping it whole, although nothing works for an extended period of time, so wherever you are going, you should move quickly!
Felt might come as a surprise because of its warm and fuzzy feel, but this quality is actually what makes it an ideal choice for insulating ice. Felt keeps ice from melting because it acts as a natural insulator. It keeps the warm air out and allows the ice cubes to survive for a long time compared to other materials. It also acts to contain the cold air that the ice cube produces, allowing it to continually cool itself off. By wrapping your ice cubes in felt, you give them the longest amount of survival time outside of the freezer.
Newspaper is another good choice, although it is not as effective as felt. Newspaper works in the same way as the felt by acting as an insulator to the ice. Wrap the ice cubes in as many layers of newspaper as you can to provide it with the thickest amount of insulation. Like the felt, the thickness of the newspaper will serve to keep the warm air out and the cold air in, so the ice cube will be able to last for a little while.
The thickness of wool allows it to insulate the ice cubes as well as the felt. The same principle applies here that applies with the other two materials; anything that can keep the air out will give the ice a chance to survive. Wool works because it is a poor conductor, which means that it does not transfer energy well. An example of something that transfers energy is metal, which is why metal is used for pipes in homes and for electricity. Wool cannot transfer energy, so any energy that enters wool will simply be trapped inside as opposed to passing through. When it comes to ice cubes, this is a good thing because any heat energy that tries to pass through will simply get stuck in the wool, keeping the ice safe.