Magic Milk

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Paint creative pictures using household items.
Watch the REACTION between the oil in the milk and the washing-up liquid.

This experiment can be a little tricky to understand, but it all involves a property of water called Surface Tension. Water molecules are attracted to one another but not in the air. The water molecules will try to make the surface as small as they possibly can to be close to one another; this is what surface tension is. Milk is in fact mostly water, so it, too, has surface tension.

The washing-up liquid is designed to break up the surface tension of water so it can dissolve and clean fats and grease in the kitchen. As a result, we can use washing up liquid's surface tension-breaking ability to break up the surface tension of the milk and as it does so, create swirls of colour.


• Whole milk
• Disposable plates (plastic are better)
• Food colouring (various) (if you don't have a dropper, put a small hole in the lid)
• Washing-up liquid
• Cotton wool buds


Experimental art:
1. Pour milk so it covers the entire plate
2. Place a few drops of food colouring around the milk in different spots. Be creative! This is your chance to create real art
3. Dip the cotton bud in washing-up liquid
4. Ready? Set? Go? Touch the milk with the cotton bud. You can place it at the centre of the plate or see what happens when you put it to one side. You don’t have to stir or move the bud at all. Just sit back and watch the magic.


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