Spherical ice cubes are about more than aesthetics. Not only do they look cool, they keep your drink cool longer, which means you have more time to enjoy the taste before it becomes too watered down.
The volume of a piece of ice provides the cooling effect, but its surface area controls how fast the ice melts — the lower the surface-area-to-volume-ratio the longer the ice will take to melt for the same cooling effect. Essentially, a lower surface area to volume ratio keeps your drink cold while delaying diluted caused by melting.
As shown in the chart below, of all the regular shapes a sphere has the lowest possible surface area to volume ratio, which is why spherical balls of ice are particularly well suited for cooling drinks.
(A cube with sides of length x will have a volume of x3 and a surface area of 6×2. The surface area to volume ratio for a cube is therefore 6 to 1 (6:1). Of all the Platonic solids (solids with identical faces) the icosahedron has the lowest surface area to volume ratio.)
The ice ball maker by iconic minimal designer brand Muji provides a easy way to create ice balls in your freezer.
Japanese bars often shave blocks of ice into spheres by hand, or mold them from blocks using expensive ice sphere devices that can set you back several hundred dollars, but if you’re not yet ready to max out your credit card with professional bar equipment, this silicon ball mold for (￥800Prices are approximate only and subject to change.
White Rabbit Express service fee and other costs not included.) will do nicely.
It’s also possible to get creative and use them for making dishes like round custard pudding. (Note: The ice ball maker is not ovenproof.)
Material: silicone resin
Heat-resistance: -20 ℃, up to 200 ℃