Simple science: Grow a paper towel rainbow

We’ve been busy creating colourful paper towel rainbows with a simple science experiment. All you need is; A piece of kitchen roll, a piece of card (empty cereal box is perfect), a few paper clips, some water-based felt tip pens and two small pots of water.

Start by cutting out a rainbow shape from the sheet of kitchen roll and colour the very ends of your rainbow (just a few centimetres from each end). Then cut a matching rainbow shape from the cereal box and secure your paper towel rainbow to it with paper clips (this isn’t essential, but the card helps prevent the kitchen towel from sagging and keeps it in place so it’s easier to see the results). Place each coloured end of the rainbow in a small pot of water and watch as the colour gradually travels up both sides of the rainbow to meet in the middle! Afterwards, carefully detach your rainbow from the piece of card and leave to dry.

You can even try doubling up your paper towel to create two identical rainbows. They make lovely window decorations too.

How does it work?

In a similar way to how a plant takes water from the roots to the leaves, the water climbs up the paper towel, lifting the ink along with it. The process is called capillary action.

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