Ok, so I’m a little excited about today’s post! Today, I’m going to explain how to make ice. Not just any kind of ice, but clear ice! I can hear some of you feigning excitement with a patronising “oh” right now. I know this is a topic I can get a bit obsessive about, like Harrison Ford in “The Mosquito Coast,” bringing ice to the natives. And I’m sure I’ve bored a few people in the past banging on about ice.
Nonetheless, clear ice is beautiful to look at and is far better quality than your standard ice. I think it can often be a discerning factor in determining the quality of a Cocktail Bar or Spirits Bar. Anyone can stock shelves with quality liquor, learn to make some popular cocktails, but it’s the attention to detail that matters. Why waste good spirits by dropping in sub-standard ice that will melt and dilute your expensive nip faster than you plan to sip it for. No, I’m looking for clear ice!
The ice we make in our freezers tends to be cloudy, and there are a few reasons for that. Firstly, freezers tend to freeze water quicker at lower temperatures. Supercooling has the effect of forming smaller and less transparent ice crystal structures. In addition, faster expansion of the water as it freezes can cause stress fractures in the ice. Finally, quickly freezing the water can trap air bubbles and impurities inside the ice.
The easiest way to manipulate ice formation in our home freezers is to make the ice using a cooler box. By using a cooler box as the container to form ice in, we achieve two things. Firstly, we insulate the water, keeping it closer to 0 degrees C. slowing down the freezing process; secondly, we control the direction of the freezing process, causing the water to freeze from the top down. This process also forces air bubbles and impurities to the bottom.
Some suggest that you boil the water you plan to make ice with to help remove impurities and air. One would hope the quality of your drinking water is better than that. Regardless, the importance of using hot water is that it helps slow the freezing process.
1. Fill a cooler box half way, with hot water.
2. Place in freezer, with lid off or open for 18 – 24 hours (you can get a sense of the thickness of the ice my the movement of air bubbles in the water below the ice)
3. Remove from freezer and allow to rest 5 minutes. Turn cooler upside down onto rack or board straddling sink. Allow to sit until ice slides out.
4. Chisel ice into desired size. To get straight lines I start the process using a serrated blade.