Since they started appearing in drinks in craft cocktail bars around 2015, clear ice cubes have come a long way, moving from being made in massive machines at high-end bars to specialty ice-making companies producing them in bulk to meet the rising demands of the hospitality industry.
What’s the appeal? First, its appearance. While serving its main purpose of chilling your drink, it’s undeniable that clear ice looks beguiling in the glass, becoming invisible once placed in your drink and slowly reappearing with every sip you take. Enterprising bars have taken to stamping large crystal-clear ice cubes with their logos as an additional decorative factor. Second, it makes for better cocktails. Large clear ice cubes melt more slowly, reducing the rate of dilution, and contain fewer impurities to affect the flavor of your drink.
With a variety of gadgets appearing on the market to sate consumer demands, some cocktail enthusiasts are tempted to spend money on molds and ice makers to keep up with the trend at home, and some of them cost hundreds of dollars. But you don’t need to shell out that kind of cash to create flawless ice cubes yourself.
The Science of Clear Ice
Clear ice is obtained through a process commonly referred to as directional freezing. Frequently used in biomimetic material design, the concept behind it is controlling the direction in which the liquid solidifies. If it solidifies from one side only, the process pushes impurities and tiny air bubbles in one direction, resulting in a pure, clear uniform structure of the final product.
In the context of ice, it means insulating five of the six sides of the container that holds water (all four sides and the bottom) to force the water to freeze from top to bottom, allowing the cloudiness from any sediment and trapped oxygen to form at the very end, at the bottom of the cube. When it’s done properly, the freezing process will be interrupted prior to the cloudy part forming, leaving you with a crystal-clear block.
How to Make a Large Ice Block
If you’re blessed with a generously sized freezer, using a small insulated cooler will give you the largest-size ice block to experiment with. Fill the cooler with filtered water and leave a bit of room (between 10% and 20% of the cooler’s total volume) for expansion as the water solidifies. “A 5-quart Coleman cooler would give me five 3-by-3-inch ice cubes,” says Adrian Wong, a bartender at Viridian in Oakland, California, who suggests those dimensions as the optimal size for ice cubes for those who want to shape ice diamonds and 4-inch-by-4-inch for making spheres. A 2-inch-by-2-inch cube works best for most rocks glasses if you’re not fashioning fancy shapes from it.
The time it takes for the water to freeze depends on your freezer, but Wong recommends checking on the ice every 12 hours. “[Because of its clarity], you can see whether there’s water at the bottom of the cooler and remove it from the freezer before it completely solidifies and cloudiness forms,” he says. “That way, it will not only be easier to get your block of ice out of the cooler, but you won’t have to waste time—and time equals melting—on chipping away the cloudy part you don’t need.”
Should you keep the cooler lid off or leave it on? “I’ve tried both and haven’t noticed a difference” says Wong. The science would seem to support keeping it off, since directional freezing requires that one side of the cube form stay uninsulated. In that case, Wong notes that having an open box of baking soda in your freezer can help eliminate any unwanted smells in the freezer (and thus in your ice) if dinner leftovers are sitting next to the cooler.
For those with limited freezer space, Ezra Star, the founder of bar consulting firm Les Enfants Sauvage LLC, suggests taking two differently sized pieces of Tupperware (or other sealable plastic containers) and stacking them one inside the other. She fills the larger one with water and places the smaller one within, then fills it with water and covers it with the lid, leaving the larger one open. She notes it’s important to use plastic containers rather than glass, since glass ones won’t be able to expand as the ice freezes, and to leave a bit of extra room inside both containers. You’ll also want to check the progress of ice formation every two hours, since the smaller volume means it will freeze more quickly than in a large cooler.
Some say that boiling your water immediately before freezing it helps remove air bubbles, improving the clarity of the ice. Others disagree. “We never boil our water prior to freezing; we use filtered tap water,” says Sebastian Törnell, a self-proclaimed “icefluencer” and the owner of Isbudet in Sweden. “I have tried to freeze boiled water once, just to see the result, but to be honest, it got even more oxygen in the ice that time than when I didn’t boil the water.”
However, using filtered water, as Törnell does, will help remove any impurities from tap water, which should increase the clarity of the resulting ice.
What follows below is a list of essential tools these experts recommend for everyone working with ice at home.
- Small kitchen towels: Opt for three to four water-resistant towels and avoid textured fabrics, as the fibers can leave undesirable indents in your ice.
- Food-safe ruler: for measuring the size of your ice cubes
- Bread knife: preferably serrated, for cutting your ice block
- Food-safe chisel: A small stainless-steel grill scraper is a good alternative.
- Rubber mallet: with which to hit your chisel or knife when cracking your ice into smaller blocks
- Heavy-duty cutting gloves
- Three-prong ice pick: It’s ideal for shaping your ice cube into a sphere if desired. “The design completely depends on your preference,” says Törnell. “The ones with a longer handle will give you more force, while the ones with shorter handles will give you more precision.”
- Paring knife: for manicuring your ice cube and making designs such as an ice diamond
How to Cut the Ice
Place a wet kitchen towel underneath your cutting board to prevent it from slipping (or you can use a medium-size bar mat as an alternative). Use a dry kitchen towel to hold the block of ice in place. Measure where you want to cut. “Allow a quarter-inch for the cut itself,” says Wong.
Begin by making straight cuts with your serrated knife along the same line around your block of ice. The cuts don’t need to be deep, but try to make them straight, as they will determine the way the ice will crack in the next step.
Place the chisel straight on your cut. The angle is very important, since it will direct where your force will go when making the crack. Using a chisel instead of the bread knife in this step gives you more control and if you deviate from the perfect angle potentially allow you to recover as you continue to crack the ice. Use a rubber mallet to hit the chisel to crack the ice into blocks of the desired size.
“You have to let your ice block temper before you begin cutting it. If not tempered, it can break in unexpected ways,” says Star who admits to having been hurt more by the ice than the tools she was using when learning the process. Additionally, tempering the ice, referred to as “seasoning” it, allows the ice to be a bit softer when you cut it with your knife.
Naturally, the ice will melt while you cut it from a big block and while you hold it in the process of chiseling it. A great trick for reducing the melting is refreezing the ice cubes after cutting them and manicuring them into desired shape after they’ve refrozen. In any case, preventing slipping of the ice and the cutting board is important. Always handle sharp tools with caution.
When choosing knives, be mindful of the material of which the blade is fashioned. “Even with quality knives, the blade will shrink when cutting ice and will expand when at room temperature; you have to pay attention to the condition of your blade as you cut your ice more often,” says Francis Stansky, the lead bartender at Pacific Cocktail Haven. Over time, the stress can lead to the blade chipping, so keep an eye out for when your blade needs extra care or replacement.
Using heavy-duty gloves will protect your hands from the sharp edges of the ice, knife and chisel blades. “When working with a material like ice that doesn’t always act the way you want, a sharp knife or a band saw can do a lot of damage,” says Törnell. “That said, I don’t want to scare people off of trying to chop ice. Just use a pair of protective gloves and common sense and go for it.” If you can’t find a pair of food-safe gloves, wear a pair of rubber gloves over the heavy-duty ones. Rubber gloves may allow the ice to slip out of your hands, however, so you’ll want to use a dry kitchen towel to grip the ice.
Storing the Ice
Whether you cut your ice at the bar with a saw or in your home kitchen with a serrated knife, your work isn’t done. Storing the ice properly is just as important as everything that came before. The amount of space you have available will need to factor into your decision about the volume of ice cubes you’ll be making. “You can only work with the volumes you can store; keep it in mind when planning,” says Stansky.
“The best thing you can do is refreeze your cut ice cubes separated from each other on a tray lined with parchment paper for two to three hours,” says Törnell. “After that, you can store the ice cubes together in a Ziploc bag or small container in the freezer.” Vacuum-sealing your ice cubes is another common practice for storing ice, and it works well to protect the cubes from taking on any unwanted smells, too.
“Spraying your cubes with vodka prevents the cubes from sticking together,” says Stansky, regardless of your storage method. The vodka allows for small bubbles to form between the cubes, making it easier to separate them without using force. “Ice will also evaporate and lose its shape if you keep it in the freezer for over a month,” says Star, so make sure you don’t leave ice cubes in your freezer for too long.
Beyond the Cube
If you find yourself comfortable with the basics, consider watching videos of Hidetsugu Ueno, a bartender and the owner of Bar High Five in Tokyo who has been teaching hand-carving ice seminars all over the world. His videos show the step-by-step process of cutting ice diamonds, as well as how to make ice spheres from an ice cube. “When using a three-prong ice pick, I like to use different parts of it to shape my ice,” says Wong. “Sometimes I angle it and use only one prong; sometimes I use all three; other times I even use the corner of the metal base that holds the prongs for more surface area.” He suggests getting tools with handles that are comfortable to you, since you’ll likely be spending a lot of time honing your skill. “When shopping for a paring knife, look for the one where the handle is close to the heel of the blade, as long bolsters in between give you less control,” he says.
You can also try making colored ice by using filtered juice (a coffee filter works best for this) or even placing a cocktail inside of your drink for an extra challenge. “Usually, I put my ice in the freezer for two hours, and once the top freezes, I place berries or flowers underneath that layer and let the water freeze for several more hours,” says Star. And if you want to get really fancy, you can go as far as freezing edible gold flakes in your ice, as Törnell and his company have done.
A quick and easy hack to making a single clear ice sphere is to place a single-sphere ice mold inside a large shaker tin and fill both with water, recreating a similar effect to Star’s Tupperware method.