Why Are Certain Ice Cubes Clear While Most Others Are Cloudy?

• Crystallization usually starts with an impurity, like a tiny speck of dust, something for crystals to grow from and build upon (also known as nucleation). 
• Ice freezes from the outside in because the tray and surface of the water are exposed to colder temperatures.
• Crystallization pushes away impurities (such as dissolved minerals and gases), therefore in the case of ice cubes, these impurities are pushed to the center of the ice cubes.

The cloudy appearance of some ice cubes is actually an indication that tiny air bubbles were trapped during the freezing process.

Cloudy or crystal clear also largely depends on the temperature of the water that is used. Tap water contains a lot of impurities, so when water freezes the impurities congregate near the middle.

Myths About Making Clear Ice Cubes at Home

Myth #1: Start with boiling water. Hot water is better at dissolving impurities (including gases) than cold water. You'll get better result maybe if you'll boil it multiple times.

Myth #2: Use distilled or filtered water. Distilled water might have less dissolved minerals and solid impurities but it may not give you the results you expect still.

Methods That Can Work

Method #1 The idea here is to mimic how lakes freeze. Insulate the bottom of the ice cube tray so it stays warmer than the top of the tray, forcing ice to slowly form from top to bottom.

Method #2 The more slowly ice freezes, the longer any air bubbles and impurities have to escape into the air instead of being trapped in the ice.

Method #3 Of course, the easiest way of all to get crystal clear ice is to get your hands on a professional-quality ice maker as they use in restaurants and bars.

How do you like these methods?

If you're talking premium liquor, you expect premium glass and ice too!