On clear ice.
You will have noticed that many of my recipes have been calling for “a big block of clear ice” and no doubt you’ve been wondering exactly where such a thing is supposed to come from. My bad. I should have explained this a bit earlier. I suppose I’ve been subconsciously delaying the inevitable because clear ice is such a, well, thing. The problem with The Clear Ice Problem is that even talking about it makes you sound like a bit of a dick. Now luckily for you I’m prepared to make that sacrifice, so let’s just accept that I’m a bit of dick and move right on. The main questions are – a) what is clear ice? b) why does it matter? c) how can I make it at home? Clear ice is ice that doesn’t contain cloudiness and bubbles. The cloudiness you see in the ice you make at home is a result of impurities and air in the water. When water freezes it purifies itself by forming a pure crystalline structure which in turn pushes impurities and air out. Consider a frozen lake. The ice is clear because it froze from the surface downward and, as it froze, pushed the impurities deeper down. Even a dirty lake freezes clear. However in your home freezer – which freezes cubes from the outside inwards – these impurities just get locked into the centre of your ice-cube. So what? Well, cloudy ice melts significantly more quickly than clear ice. You may even have noticed this yourself. The ice machines in most bars make clear ice that lasts much longer than the cloudy ice you make at home. This means your drink stays colder longer and doesn’t get as watery toward the end. Shaking or stirring with cloudy ice isn’t really a problem but for any drink served “on the rocks” it makes a big difference. As an added bonus there is nothing quite as beautiful as a big crystal clear iceberg floating in your Negroni.
The Clear Ice Problem – more specifically making clear ice at home or without spending a fortune on a commercial ice machine – has been driving professional and amateur cocktailiens nuts for years. All sorts of crazy ideas have been discussed on the internet. I’ve found only one of them that really works and luckily it’s also quite simple. Commercial ice machines make clear ice because they freeze like that lake – in one direction. We call this “directional freezing” and there’s an easy way to do this in our own freezer. Here we go:
Buy one of these. It’s a Coleman 5 litre/4.7 quart cool box. It’s designed to keep a lunch or six-pack of 330ml cans cool and it also makes a great ice bucket so you’re getting 3-for-1 value here. They are fairly cheap and available on Amazon. You could get another brand but make sure it fits in your freezer and that the lid comes off.
Fill it with water, leaving a bit of space for ice expansion, and put it in your freezer. Turn it around after about 12 hours to keep it freezing evenly. The important thing is that you don’t freeze all the water. There should be at least 2-3cm (1″) of liquid water left at the bottom. How long? That depends on your freezer but usually between 24 and 36 hours. Note how long it takes to freeze to the desired level for future batches. In the example pictured here I left it a bit too long and it almost all froze. That’s not a disaster but it makes more work for you later.
Take the cooler out of the freezer and let it rest for at least 10 minutes. Don’t worry, it won’t melt, we just need it to warm up a little so that it doesn’t shatter when we carve it. Meanwhile get your tools together. You need couple of clean, dry towels of the non-fluffy kind, a clean bread-knife, a wooden or rubber mallet and some new large zip-lock bags. An ice-pick might be handy but isn’t essential. Wash your hands and clean your sink.
Turn the cooler into the sink and tap the bottom until the big block of clear ice slides out. You might want to have a clean towel or chopping board in the sink to keep the ice clean.
Put the block on a towel (or bar mat as shown) right beside your sink. From here on you need to work fairly quickly but carefully – please don’t cut yourself. Trim the block until you have a regular shape using the bread knife. If you removed the cube before if froze right through this should be pretty easy. If you left it too long, like I did this time, trim off the cloudy ice from the bottom. The cloudy ice cuts quite easily (that’s right – because it’s full of air and impurities). Now carve the block into slabs and then cubes by making a score with the bread knife (be very careful when starting the cut – that’s when the knife is likely to slip) then tapping the knife firmly with the mallet. You’ll be surprised how linearly the ice splits (mostly).
Continue to make cubes that are just the right size to snugly fit into your DOF glasses. They’re not going to be perfect cubes but that’s fine. Sweep the shards into the sink as you go and put the cubes into a zip-lock bag. When you’re done put all but one of your lovely diamonds of clear ice in the freezer for future use and make yourself a Negroni or maybe a Lord Lucan.
Now if I could only come up with an effective way to make clear ice balls…
XXX UPDATE XXX
I came up with an effective way to make clear ice balls.