Try this at home: Layered drinks!
Impressive and tasty layered drinks can be made at home too. All you need is a teeny bit of practice.
In films you can sometimes see drinks with different coloured layers on top of each other. Everyone knows that oil floats on top of water, but a water-olive oil -drink doesn’t sound too tempting…
Don’t worry, two water solutions can also be placed on top of each other. These could be for example two juices of different colour or a juice and a milk-based drink.
The most important thing is to use drinks with different densities. The most dense (most sugary and “heaviest”) drinks go to the bottom and less dense drinks (light drinks and foamed liquids) go on top of them. If the drinks are cold, the layers will keep apart longer.
The idea is to pour the lighter layer very slowly along the stem of a spoon. The other end of the spoon is placed just above the lower layer and the liquid is then poured very carefully from a beaker or jug. Capillary forces will then hold a small amount of the liquid on the spoon and let it run down. If there’s too much liquid, it will form drops and drop of the spoon and cause the layers to mix.
In this video the bottom layer’s sugar concentration is first increased by dissolving some additional sugar to it. Then a layer of milk with some cocoa powder is added. You could still add an extra layer of diluted sugar-free orange squash. However, you don’t want to mix milk with very acidic juices because some cheese will form between the layers.
If you want, you can make layers of any colour or taste with food colouring, sugar and flavored mineral waters, for example. You will want to boil the bubbles out of a fizzy drink and cool it before use. Otherwise bubbles will mix the layers. Or you can just stick to juices.
Jan Jansson is a chemistry teacher that spends his little free time doing molecular gastronomic experiments.