Ice, Ice Baby
As cocktail culture grows around the world, people are starting to pay much more attention to everything that goes into the glass. The spirits, the juices and the garnishes in our cocktails have all undergone serious improvements in the last two decades, and the champagne coupe has had a rebirth as a glass of choice in many craft cocktail bars. But it's only in the last half-decade or so that the eye of your local mixologist has really turned toward scrutinizing the ice in your drink. The Aviary bar in Chicago even has an "Ice Guy", whose full-time job is creating the wide variety of ice used in their incredibly creative drinks.
It's hard to imagine a time when people didn't have ice in their drinks, but the original settlers to America used to warm their drinks even in summer, thinking that the sweat produced by drinking them would cool the body. It wasn't until the early 1800's that people started putting ice in their drinks, mostly because of one very creative Frederic Tudor, who by the 1830's was shipping ice from Boston (where he had harvested it from the rivers in winter) to India! Here's another article about Tudor.
With the return of tiki drinks and a new respect for the classics, bars can no longer get by with simple cube ice. Crushed ice, cracked ice, and large cubes affect both the chilling, dilution and presentation of the cocktails. Kold Draft ice machines make uniformly perfect one-and-a-quarter-inch cubes that don't break apart in the shaker. Both the shape, size, and temperature at which ice is frozen impact how it reacts to the violence regularly done to it in the shakers and stirring glasses of the nation's bars.
As I've been building out my home bar, I've had the luxury of playing with bar techniques and technology without having to commercialize the results of my experiments, a luxury few bar owners have. I'll be writing soon about my experience clarifying citrus and carbonating cocktails, but my most successful and replicable recent experience has been with making perfectly clear ice.
In making clear ice, I've relied almost exclusively on the ice research that has been done by Camper English on his Alcademics blog.
Per Camper, I started with an Igloo cooler, filled it with water, put it in my freezer and propped the lid open. When normal ice freezes it freezes from the outside in, trapping the gases and impurities in the middle. With the cooler, because of the insulated sides the ice freezes from the top down pushing the gases and impurities downward as it solidifies. Depending on how long you leave it in the freezer (in my case, 3 days), you can either take it out while there is still some unfrozen water, or you can wait for it to freeze completely and cut the cloudy ice off of the bottom of the block.
Because I took the ice out before it had frozen completely there was a big pocket of unfrozen water in the bottom that I cut off to achieve a nice slab of clear ice. I just used a bread knife to cut the extraneous ice off of the bottom. If it freezes solid, I score it with the bread knife and use my Lewis Bag mallet on the knife to break the cloudy part off of the ice block, leaving me with the clear ice slab. I'm sure anyone with a nice set of knives is cringing as they read this, but you probably shouldn't be buying expensive bread knives anyway. If you're unconvinced, use a saw.
Because of my love for sous-vide cooking (see a few links below) our kitchen has pretty much turned into a food and drinks laboratory. A great side effect of all this is that there are lots of fun toys to play with, including the carbonator and centrifuge (which I use for clarifying liquids, usually juices). One of my most oft-used gadgets is a chamber vacuum sealer, in my case a VacMaster 215c . It's basically an industrial-strength Foodsaver that sucks all (well, most) of the air out of bagged food. What this means is that food doesn't suffer as readily from freezer burn if it's frozen and that it also lasts much longer in the refrigerator and freezer without spoiling (it's saved us hundreds of dollars in spoiled cheese since its arrival).
Occasionally a use for the chamber vac comes up that I didn't anticipate. As a result of this clear ice method, I now have the raw material for a) perfectly clear chunks of ice to keep the punches cool that I make for my parties, and b) raw material for what's probably the most extravagant device I have in my kitchen, the Cirrus Ice Ball Press (more later). The problem is that I can only make one Igloo ice slab at a time (which takes 3 days!) and as anyone who has used ice trays knows (even the really good ones from Tovolo, a necessity in any freezer), over time the ice will sublimate in the freezer, evaporating enough to ruin the perfectly shaped ice cubes you made.
The chamber vac allows me to seal (in perfectly air-tight plastic bags) not only the ice slabs I've made in the Igloo cooler, but also allows me to save any ice I've created using the Tovolo trays, Tovolo ice sphere molds or the ice press, which means that I can store them worry-free until such time as I need to use them. Unfortunately, this also means that my freezer at work has been completely filled with bags of ice. Some in packs of 30-40 cubes and some individually wrapped ice spheres.
So, what can one do with perfectly clear ice slabs? Well, besides floating them in a punchbowl as a aesthetically pleasing garnish or using them to display sushi or other cold-served food, what I've been using them a lot for is as the raw material for the ice press. The Cirrus Ice Press is a huge chunk of heavy aluminum that relies on its perfectly milled spherical core, its conductivity and its weight to melt a cube of ice into a perfectly spherical ice ball. Mathematically a sphere has the smallest surface area of any geometrical shape, which means that it will melt more slowly in a cocktail. Plus, it looks wicked cool and the process allows for a minute or two of contemplation (or, time to build your cocktail!)
In my case, it was a very generous gift from some friends of mine and while I don't think I would've purchased it myself, if you like the idea of owning one, very similar but less expensive versions of it are now available at Cocktail Kingdom. The beauty of the clear piece of ice cut from a slab is that it results in a perfectly clear ice ball, which will actually act as a lens if you look through it. Functionally it's no different than using a non-clear sphere made using the Tovolo spherical ice molds, but it certainly does look different sitting in a rocks glass.
Besides the Cirrus Ice Press, the Cocktail Kingdom "replicas" and the Tovolo Ice Sphere Molds, there is also a Kickstarter project meant to help you more easily make clear spherical ice balls. If the idea appeals to you, go support them! Finally, if you're feeling a little stabby, you can always chip away at the large ice chunk by using a ridiculously sharp ice pick (or a knife) to get rid of every part of the ice chunk that doesn't look like a sphere.
So, aside from the Igloo cooler method, what else can an ice obsessive do to experiment?
Kevin Liu at Science Fare describes an alternative to Camper's directional freezing method, using what he calls "high temperature freezing", but it requires a bit of an investment in a dorm-room bar fridge. The article is worth reading to understand why the ice in our freezers normally winds up cloudy, and has some great photos illustrating the process. If the idea of learning more about ice intrigues you, take a look at Kevin's article at Serious Eats that debunks several myths about ice.
Science writing in the name of better food and cocktail preparation has become a passion of mine via websites like ChefSteps.com and cookingissues.com. Kevin's new book Craft Cocktails at Home and its accompanying blog are worthy additions to my reading list and are both excellent resources for you or the cocktail nerd in your life.
In future articles, I'll start freezing liquids other than water and seeing if there are ways we can use them in cocktails that help modify the taste of the drink as they melt. I also want to further develop something I've been playing with lately - using commonly available kitchen gadgets to make and serve a cocktail *in* an ice sphere.