This is the second part of my series of recipes from Liquid Intelligence. I’m going to make all of them, which you can see here.

In Liquid Intelligence, Dave Arnold explains how to make clear ice. What makes ice cloudy is solids and gasses dissolved in the water. As an ice cube freezes, the water freezes into crystals first, forcing solutes away from the new ice crystals. Because the ice in a normal freezer is freezing from the outside in, those solids are forced toward and concentrated in the center of the cube.

The solution is to do what an ice sculpture machine does and freeze from one direction to the other. The easiest way to do that at home is via insulation. Put your water in a cooler, and leave it in your freezer with the lid open, and it will freeze much faster from the top than from the sides and bottom.

So I bought a small 10 quart cooler from Amazon. You’re supposed to load it with hot water, since hot water has fewer gasses in solution. You want to let it drop in temperature as much as possible before putting it in the freezer, otherwise you’ll get a ton of condensation from the evaporating hot water on everything else. Figuring it would take a year for the hot water to cool in the insulated cooler, I put the hot water in a stockpot until it cooled to room temperature, then gently poured it into the cooler, which I then placed in the freezer.

Here’s a picture at the start:

You might not be able to make it out from this image, but after about one day the ice was frozen a couple inches from the top.

After another day (approximately 50 hours in) I took out the cooler and unmolded onto a towel next to my sink. (I need a large bar mat for next time!)

As you can see it was only frozen about halfway through. I wanted to practice cutting it anyway, figuring my technique would need some work, so I didn’t put it back in the freezer and just went ahead. I suspect a third day would have it frozen very close to the end.

I first cut off the unfrozen part, of course drenching my kitchen in the process. After trimming it, I got about a 2.5” thick slab. Here’s what it looked like:

Arnold’s method of cutting is pretty simple. You use a large serrated knife (I used my bread knife, since I almost never cut bread anyway) to score the ice on both sides. Then you simply put the blade into one of the grooves you created and tap on it and voila. Arnold is right when he says that it looks a lot more impressive than it actually is. Here it is cut into columns, with one column cut into chunks:

I used it in an Oaxaca Old Fashioned from Death and Co.