Lava lamps are fun. It’s satisfying the way the blobs flop and float about, rising and falling in the tube… but wouldn’t it be more fun to make your own?

X-Peri-Mas #6 made something that looked a bit like a lava lamp – with oil and water swapping over between two containers but this one is even closer to the real thing.

What you will need

  • A long, thin container like a measuring cylinder
  • Oil – colourless works best (baby oil)
  • Food colouring
  • A fizzy tablet or bicarbonate of soda

How to do it

Pour a little water into the container to get quite a short layer at the bottom. Now pour in the oil, leaving about 5 cm free at the top in case the whole thing fizzes over and makes a mess.

Add a few drops of food colouring and watch them fall through the oil. If you’re lucky the colour will sit at the boundary between the oil and the water at first and then slowly diffuse and spread out like tentacles into the water. Soon enough you’ll have an even colour of water in your container.

Now to make the bubbles that will rise and fall in your container. Drop in a small chunk of a fizzy tablet – it will fall all the way through the oil and sink through the water too and start to fizz. The gas that is released with form into bubbles that will rise all the way up – carrying some water with them as they go. The coloured water blobs will be dragged up with the bubbles all the way to the very top of your cylinder but then pop! Without the air there to help the water float it will sink again through the oil layer and settle back into the bottom of your container where more fizz will form and carry a new blob right up again.

The less water you have the slower the bubbles will form but it can make the whole thing look a lot better if you’re patient.

Get involved

Share pictures or videos of your attempts with #XPeriMas on Twitter – I’d love to see them.

PS: Yes, I did accidentally make an experiment that looks like it is raining blood. I’ll crack it out next halloween…

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