When you splurge on a cocktail in a bar, the drink often comes with a slab of aesthetically pleasing, perfectly clear ice. The stuff looks much fancier than the slightly cloudy ice you get from your home freezer. How do they do this?

Clear ice is actually made from regular water – what’s different is the freezing process.

With a little help from science you can make clear ice at home, and it’s not even that tricky. However, there are quite a few hacks on the internet that won’t work. Let’s dive into the physics and chemistry involved.

Homemade ice is often cloudy because it has a myriad of tiny bubbles and other impurities. In a typical ice cube tray, as freezing begins and ice starts to form inward from all directions, it traps whatever is floating in the water: mostly air bubbles, dissolved minerals and gases.

These get pushed toward the centre of the ice as freezing progresses and end up caught in the middle of the cube with nowhere else to go.

That’s why when making ice the usual way – just pouring water into a vessel and putting in the freezer – it will always end up looking somewhat cloudy. Light scatters as it hits the finished ice cube,........

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