Create Perfectly Clear Ice at Home
Updated: May 30, 2020
Have you ever wondered how cocktail bars make crystal clear ice cubes for your drink? Here's how you can do it at home.
Before we delve into how to make crystal clear ice, it is time to address the elephant in the room: why would anyone want to make clear ice in the first place? Don’t clear ice and regular ice do the same thing? Clear ice won’t chill your drink better, but a proud mixologist uses it for the same reason a chef doesn’t just glop food down on a plate—craft and presentation matter.
Your meal might taste great, whether it’s stylishly plated or not. But if your food looks boring when it arrives, you may wonder why you just spent all that money. A colorful, curated plate immediately tells you that you can trust the chef, and that they take their craft (your meal) seriously. You trust that your meal is better because it looks better.
Clear ice has the same effect. It shows that you take cocktails seriously and are willing to sweat the details. You might be a nerd, but you’re a nerd that cares. Luckily, clear ice isn’t just cool; it’s also easy to make at home.
What is Directional Freezing?
The easiest way to make clear ice at home is a method called directional freezing. Directional freezing is a simple method that controls how water freezes, forcing air bubbles and impurities to move in one direction. Camper English of Alcademics first pioneered the directional freezing method for home use in 2009 (see the original article here). After trying and failing to achieve clear ice by using boiled or distilled water, Camper decided to look at the way water freezes instead.
After much experimentation, he determined that ice is cloudy because of trapped air, not because of impurities in the water. Boiling or using distilled water might make slightly clearer ice, but because air is still trapped as the water freezes, you will still have cloudy ice.
Take an ice cube out of your freezer. Notice that cloudy white spot in the center of the cube? That white spot is trapped air. When water freezes in an uninsulated ice tray, it freezes from all directions at once. Because air pockets freeze last, the air is forced into the middle of the cube, where it becomes trapped. Directional freezing fixes this by freezing water from the top-down only instead of outside-in. Rather than becoming caught in the middle of the block, the air is instead pushed to the bottom of the container. The top of the block, however, is free of air bubbles and, therefore, crystal-clear.
How to Make Clear Ice
Using directional freezing to create clear ice at home is an amazingly simple process. You will need:
A small cooler that can fit in your freezer
A serrated bread knife you don’t mind nicking up
A mallet, preferably wood or wrapped with leather to prevent damage to the knife
A cutting board
A faucet or water gallons
Step 1: Freezing
First off, remove the lid from your cooler. For directional freezing to work correctly, the top needs to be uninsulated. Fill the cooler up to about an inch from the top and place it in the freezer. Freezing times will vary based on your freezer’s temperature, but 24 hours generally works best. Your goal is to stop the freezing process before the entire block freezes. The top of the block should be frozen a little more than halfway down while the bottom should be watery or only partially frozen.
Step 2: First cuts
After about 24 hours, remove the cooler from the freezer. Place a large cutting board on the counter or preferably in the sink. Water will get everywhere. Turn cooler upside down on top of the cutting board. You may need to gently pull apart the sides of the cooler from the ice block to help dislodge it. Once the ice block is free, you should see a crystal-clear layer with a watery, partially frozen layer on top. Chip away at the partially frozen shell with your bread knife and drain any trapped water. Don’t worry about shaping the block perfectly at this point. Run the block under some warm (not hot) water to even out some of the rough edges. You should be left with a crystal-clear block of ice.
Step 3: Shaping the ice
There are two types of cubes you can make with your clear ice block. You can make perfectly cubed blocks for rocks glasses or make long rectangular sticks for Collins or highball glasses. Think of what you want before you start cutting the block.
With your serrated knife, saw back and forth to cut a little slit in the ice. Hold your knife steady and gently hammer it with your mallet until the ice gives way. It should break cleanly along the slit. Repeat the process on the smaller block and shape it into a perfect cube for rocks glasses or a stick for highball glasses. If the cubes are too large for your glassware, use your bread knife to shave them to the correct size. You can run the cubes under warm water again after shaving to smooth out rough knife edges. Store your clear ice in a large Ziploc in the freezer for future use.
That’s all there is to it. Now you know how to make clear ice at home. Clear ice is a simple, eye-catching way to enhance your craft and impress your guests.