Curious Kids Science

Magic Rainbow Milk Experiment

Magic Rainbow Milk Experiment

Magic Rainbow Milk

This is a fun experiment that takes almost no planning and requires very little clean up afterwards. Easy for a quick after school activity.

Challenge: Can you make milk move with only a tiny touch?


  • Homogenised full fat cows’ milk. Enough to cover the bottom of a shallow dish so that it is about 1cm to
  • Liquid food colours. Three or 4 colours is best but you can see the results with 2 colours
  • Dish washing detergent. The type that you use when washing dishes in the sink
  • Dropper or syringe
  • Cotton buds
  • Shallow dish


  1. Pour the milk into your shallow dish. Make sure that the milk covers the bottom of the dish and that it is at least 1cm deep.
  2. Use a dropper or syringe to put drops of food colour or liquid water colours on to the surface of the milk. Try not to mix them.
  3. Place a small amount of detergent on to the tip of the cotton bud and gently dip the cotton bud in the milk right next to some of the colour drops.
  4. Watch the magic happen!

The Science

Homogenized milk has gone through a process where the fat is broken up into tiny pieces called globules. These are all throughout the milk.

When you added food colouring to the milk it floated on top. This is because food colouring is less dense (heavy) than milk.

When detergent touches the surface of the milk, it begins to dissolve the fat globules. This process (along with several other things that are going on) causes movement in the milk. The movement in the milk causes the colours to move and mix.

What you are watching is an example of a chemical reaction.

For more exciting experiments why not grab our Chemistry-in-Action kit?


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