If you’ve ever sipped an $18 bourbon rocks at a classy tavern in South Florida, chances are good those rocks came from Mixology Ice. At his chilly warehouse northwest of Miami International Airport, Leal and his partner, Fabian Alvarez, pump out massive blocks of clear ice every five days. These icemen start with tap water, which flows through a five-step filtration system that peels away impurities. Once filtered, a $5,000 freezer called a Clinebell chills the water into two 300-pound blocks. Leal says that ice is then painstaking carved into Collins rods, chiseled into two-inch cubes and molded into spheres...

...Local high-end bars swear by clear ice’s benefits. Premium liquor deserves premium ice that won’t melt fast, they say, and it doesn’t hurt business when patrons post their fancified drinks on Instagram.

Cocktail author Jim Meehan recalls working in a bar in Wisconsin in the 1990s. 

“Ice was just a utilitarian thing.” he said. “It was frozen water that was used to keep drinks cold.”

That frozen water was usually cloudy, full of impurities and air bubbles. Around the turn of the century, though, the craft cocktail renaissance began; bars threw out pre-made mixes and started using fresh juice and top-shelf spirits. And crystal clear ice started to appear in cocktails.

The first clear ice cubes were made from an ice sculpting machine, which freezes water in a way that pushes out impurities or air. Meehan was running a bar in New York at the time and he was skeptical.

“I believe the original costing on this ice was around 75c a cube, which is a pretty considerable cost per drink,” he said. The visual appeal, however, eventually won him over.

“It makes a dramatic difference in the drinks,” Meehan said. “One of the things I’ve always said to bartenders, and anyone who would really listen, is that we taste with our eyes first.”

“Ice is the most important part of your drink,” declares Jay Khan, founder of the agave-focused bar Coa. “It controls the dilution and temperature of your cocktail. I’d say that 98 per cent of our drinks here use ice, so it’s essential. Not to mention, good clear ice just looks sexy.”
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Many crucial steps go towards the creation of the perfect cocktail – a good base, the right vessel, an accurate shake or stir – but that frozen water could be so crucial is a surprising professional confession in an industry that has become more upscale in recent years.

Even if you’ve perfected your mixology skills and filled your cabinets with fancy glasses and bartending tools, your homemade Old Fashioned or Aperol Spritz will never live up to the ones served at a craft-cocktail bar if you use cloudy ice cubes that smell vaguely like the leftovers you’ve been storing in the freezer. As Mathew Resler, the head bartender at Bar Goto, says, “Ice is an integral ingredient when making cocktails. The appearance, dilution ratio, taste, and purity are all essential to a proper drink.”
Resler and the other bartenders I asked about how to make perfect ice all pointed me to journalist Camper English, who writes about cocktails and spirits and pioneered the technique that most professionals now use to make ice (after experimenting with the frozen stuff for a decade).