How Cocktail Ice Visually Vanished

Absolutely clear cocktail ice—transparent as Steuben glass, free of disfiguring air bubbles—has been something of a holy grail among home hosts for decades. As early as 1963, a clearly frustrated Mrs. C.H. Halneisan wrote to her local paper in Akron, Ohio, asking if anyone could tell her “how to make ‘crystal clear’ ice cubes using my own trays and refrigerator. I have asked this question for years but no one seems to know the answer.”

With all due respect to Mrs. C.H. Halneisan, this wasn’t exactly true—many people claimed to know the answer to this question, which was asked with surprising frequency throughout the 20th century. In her case, the advice columnist told Mrs. Halneisan to fill the ice cube tray without the divider, stir it four or five times over a 15-minute period, then replace the divider and freeze.

Many other suggestions arose over the years for making clear ice. Some claimed distilled water did the trick. Others insisted on demineralized water or hot water. Or freeze it once, thaw it, and freeze it again. Boiling the water and letting it cool was perhaps the most common suggestion, with some decreeing the water should be boiled twice. Putting an ice tray in a plastic bag was recommended (“to avoid condensation”), as was installing are verse osmosis system, requiring “an under-sink installation linked to a third faucet.”

While diverse, all these methods shared precisely one thing in common: disappointing results. To one degree or another, all produced ice that was at least partly cloudy.

With the rise of the cocktail renaissance in the late 1990s, the quest for clear ice arose anew, this time led by a new generation who brought renewed vigor and a measure of science.

Among these was Camper English. A spirits writer based in San Francisco with a background in science, he was curious about the physics of clear ice. By the 1990s, commercial outfits were producing large blocks of clear ice for banquet and wedding sculptors. In New York, clear cubes were sold wholesale to bars. But how to do this at home? “I decided to just test some stuff out systematically, not expecting to actually figure anything out,” English says.

His early experiments included the “freeze twice” theory, and he published the results on his blog, Alcademics. (“I repeated the freezing something like 12 times,” he reported. “It’s not getting any clearer, folks.”) He started with hot water and then very cold water, and set his freezer at various temperatures. He tried carbonated water, “which made the cloudiest of ice.” The results were always the same.

When ice freezes, he noticed, the last part to solidify was always the cloudiest. English tried freezing ice in thin layers, which resulted in striped ice. He launched other experiments “focused on trying to eliminate that last trapped gas in the middle of a cube, which had me doing things like poking a straw into the middle of a freezing block of ice,” he says. He ended up with a cloudy block and a straw full of frozen water.

Then he became aware of what’s now widely called “directional freezing.”

When ice freezes, water’s molecules form a tight latticework, squeezing out impurities—such as dissolved oxygen, which becomes entrapped in the remaining liquid. Since an ice cube tray is subjected to cold from all sides, the air bubbles often end up huddled in the center of the cube, refugees from freezing temperatures.

Control the direction of the freezing, and you can largely control where the impurities end up. The method English devised was to use an insulated container, like a small hard-sided beer cooler, filling it with water and putting the whole cooler, sans lid, in a freezer. This would confine the freezing from one direction, the top, forcing impurities to the bottom, where they could be chiseled off, leaving perfectly clear ice. Making diamond-like ice, it turns out, is a bit like distillation—using a mechanical means to separate elements in a liquid.

Word spread, fueled by discussion boards and blogs, English’s prominent among them. The method was commercialized, and a number of companies began producing home freezer devices with dual insulated freezing compartments, one to collect air-bubble ice and one leaving the clear ice. Countertop machines designed to produce clear cubes and spheres have since proliferated, including the “Clear Ice Ball Maker with Crystal Flux Technology.” (Review: “I’m never left waiting long for a chilled drink. … App and voice control make it super convenient to start a batch or check status without even walking into the kitchen.”) Mrs. C.H. Halneisan would undoubtedly be pleased.

Of course, the question remains: Why does anyone care? Cloudy or not, ice won’t really change the flavor of your drink. Yet it can surely influence your experience of a drink. “To me, clear ice elevates the whole experience,” wrote a bartender on Reddit. “If I’m at a craft cocktail bar paying premium prices, I expect a premium experience. Is it necessary? No. But it defines luxury.”

“I hope we’re never going back,” says English. “Visually, it’s so much better.”

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