How to Make Crystal Clear Ice Cubes

Tips and Tricks for Clear Ice

Clear ice forms when water is pure and doesn't contain dissolved gases. The easiest way to make clear ice is to use boiled water.
Clear ice forms when water is pure and doesn't contain dissolved gases. The easiest way to make clear ice is to use boiled water. photo by dasar/Getty Images

While you are making glow in the dark ice, why not make some clear ice? There is a "trick" to making clear ice cubes, but it isn't complicated and doesn't require an expensive restaurant ice machine. You need pure water and you need to control how it cools.

The ice maker in a typical home freezer has a water filter, but usually produces opaque ice. This is because the water doesn't cool at the right rate to produce clear ice or else there is a lot of air in the water. Clear ice is easily made using bottled water that had been purified using reverse osmosis or distillation, but you can make clear ice from tap water. To do this, boil the water to remove most of the dissolved air. Ideally you want to boil the water, let it cool, then reboil again. But, you should be able to get good results just boiling the water once. Let the water cool slightly to minimize the risk of getting burned and then pour it into an ice cube tray and put it in the freezer.

So, you can make clear ice by boiling and freezing filtered water, but the cooling rate is also important. If the ice freezes too slowly the result is milky on the bottom and clear on top. Unfortunately, you don't have a lot of control over the freezer's cooling rate. You can play with the starting temperature of the water until you get the results you desire.

What can you do with clear ice? One thing you can do is to use it as a magnifying glass. In a pinch, you can use an ice lens to start a fire. Also, unless you like the taste of quinine, clear ice tastes a lot better in drinks than glowing ice.