The trick to making ice cubes last as long as they do in bars

Why is it that ice cubes at home melt faster and turn your drink into a watery mass, yet your bartender's ice stays chunky and cold until the glass is empty?

Martin Wolf, a bartender at Berlin's historic Frederick's bar and restaurant, spills the secret with three cool serving hacks.

Double freezing: "To make ice last longer, double freezing helps," is Wolf's top tip. Fill water into a cube maker and freeze. When the cubes are well frozen, pour them onto a plate or into a freezer bag and freeze them again.

Go big: People tend to think that putting a lot of ice in the glass will water down the drink. "The opposite is actually the case," says Wolf.

This is because many ice cubes cool each other, especially giant ones. "The larger the ice, the lower the ratio of surface area to volume. And this results in a longer cooling capacity and means that the ice melts more slowly."

Square is more: Round ice cubes may be easier to push out of ice cube makers - "but square cubes are better than round ice moulds because they offer a greater surface area and therefore cool for longer."