Living it up with a homemade lava lamp

Living it up with a homemade lava lamp
Children’s Corner

The pandemic has been a stressful time with everyone not being able to socialise or go to school for so long. Despite Ireland beginning to reopen, it can be tough to get back to normal life.

Why not make something that helps people relax? Lava lamps are undoubtedly satisfying to observe, there’s something quite calming about the way the floating blobs in the lamp move.

Using simple household items such as vegetable oil, food colouring, Alka-Seltzer and a bottle to create chemical reactions and globules of colour, it’s easy to create a tranquil space with your very own lava lamp.

  • Water
  • A clear plastic bottle (or jar)
  • Vegetable oil
  • Food colouring
  • Alka-Seltzer (or other tablets that fizz)


  • Pour water into the plastic bottle until it is about one quarter full.
  • Pour in vegetable oil until the bottle is nearly full.
  • Wait until the oil and water have separated.
  • Add a dozen drops of food colouring to the bottle (choose any colour you like).
  • Watch as the food colouring falls through the oil and mixes with the water.
  • Cut an Alka-Seltzer tablet into smaller pieces (around 5 or 6) and drop one of them into the bottle, things should start getting rather dramatic, just like a real lava lamp!
  • When the bubbling stops, add another piece of Alka-Seltzer and enjoy the show.


What’s happening?

Previously in this column we looked at the relationship between oil and water and how they just don’t like to mix. The oil and water added to the bottle separate from each other, with oil on top because it has a lower density than water.

The food colouring falls through the oil and mixes with the water at the bottom. The piece of Alka-Seltzer tablet dropped in afterwards releases small bubbles of carbon dioxide gas that rise to the top and take some of the coloured water along for the ride.

The gas escapes when it reaches the top and the coloured water falls back down. The reason Alka-Seltzer fizzes in such a way is because it contains citric acid and baking soda (sodium bicarbonate), the two react with water to form sodium citrate and carbon dioxide gas (those are the bubbles that carry the coloured water to the top of the bottle).

Adding more Alka-Seltzer to the bottle keeps the reaction going so the lava lamp can be enjoyed for longer.

When your Alka-Seltzer stores are depleted, you can take the experiment a step further by tightly screwing on a bottle cap and tipping the bottle back and forth, what happens then?