We think this DIY lava lamp is brilliant: not only is it eye-catchingly cool, it's also a science experiment that teaches your kids about liquid density – basically, how some liquids are heavier than others.


You don't need any fancy ingredients – you've probably got most of them at home already – and it's super-quick to make.

The science behind a homemade lava lamp

The secret behind the lava lamp is liquid density – in this case, how much matter is packed into the different liquids.

Oil and vinegar have different densities. Vinegar is more dense than oil, so this is why it sinks to the bottom of the glass.

Once it reaches the bottom, it touches the bicarbonate of soda. This causes a chemical reaction that releases bubbles of the gas carbon dioxide.  The bubbles of carbon dioxide attach themselves to the vinegar and cause it to  float to the surface with them.

But once the carbon dioxide bubbles reach the top, they escape into the air. So now the vinegar globules start to sink again.

Here’s how to make a lava lamp

Help your child to learn all about liquid density in a truly genius and genuinely fun way

You will need:

  • 3tsp bicarbonate of soda
  • Tall glass or bottle
  • Vegetable oil
  • Small cup/jug
  • Teaspoon (for mixing)
  • White vinegar (can be any type of pale vinegar)
  • Food colouring of your choice

Step 1: Add the bicarb

how to make a lava lamp step 1

Put the bicarbonate of soda in your glass or bottle.

Step 2: Pour in the oil

how to make a lava lamp step2

Fill the glass or bottle about 2/3 full with the oil. Don't mix or shake the oil and the bicarbonate of soda together.

Step 3: Prepare the vinegar


In your small cup or jug, mix a little vinegar with a few drops of food colouring.

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Step 4: Add the vinegar

how to make a lava lamp step 4

Really slowly, add drops of your coloured vinegar mix to the glass or bottle, trying not to let them run down the inside of the bottle but instead drip directly into the oil.

Watch as your lava lamp starts to float and bubble. For full-on hippy-dippy atmosphere, you could turn the lights off, close the curtains and shine a torch behind the bottle!

Pics/video: Danielle Graph


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Dani Graph
Danielle GraphCommunity Manager