Let's make a rainbow

There is more than meets the eye with this experiment. Use some household items to pull apart colour and create some gorgeous art.

Did you know your black textas may be hiding other colours? We can use chromatography - the science of separating the different parts of a mixture to check this out. We will be using a process called capillary action to draw inks and water up some paper to investigate colour. Using this process you can then produce a beautiful rainbow design!

For this activity you will need some absorbent paper such a coffee filter or a piece of paper towel, scissors, a black texta or whiteboard marker- but not a permanent marker, water, a tall glass or container and a clip or peg.

  1. Cut a strip of paper or water filter around 2cm by 15cm
  2. Take your texta and draw a thick line about 3 or 4cm from the bottom of the paper.
  3. Put a small amount of water into your glass then place just the very bottom of the paper into it, making sure you don’t put your texta line under the water.
  4. Fold the top of the paper over the top of your glass and secure it with your peg or clip. Watch the water slowly creeping up the paper and notice what happens as the black ink starts to move up the paper. Is the ink still black?
  5. Wait until the ink has made its way to the top of the paper strip. How many colours can you see now? Did any colours travel farther than the others?

Capillary action is the process that let us draw the water up the paper. Did you know that water molecules like to stick together? This means that as water travels up our paper, it drags other water molecules with it. The ink of our texta has water in it so the colour gets pulled up the paper, revealing the mix of colours that are used to make up your black texta.

What other artworks can you create? We would love you to share your creations with us by using #Scienceworks #MuseumAtHome.

Have you ever wondered... 'what is colour'? Physicist and chemist Dr Kyra Schwarz with Exciton Science is here to help us learn about light, rainbows and colour!

The researchers at the ARC Centre of Excellence in Exciton Science are working towards a renewable energy future by developing and uncovering the materials that will allow us to more efficiently convert light into electricity and electricity into light.

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