Milk and dishwash liquid - An experiment on surface tension

This was the first ever experiment that we tried at home. We picked this for our little A as this was quite the perfect mix of art, science and fun.  A was 3 years old at that time and even now, it is her favourite one. She keeps asking for a repeat of this one just for the fun of it. I generally prefer experiments which use a lot of colour - the never fail to fascinate. Like I said, this was quite the right mix.

You will typically have all the ingredients sitting in your kitchen shelves, even in the most diverse of situations. What you need are –

• A wide pan – I took a steel dinner plate
• Food colouring – as many colours as you can have
• Dishwashing liquid
• Milk
• A toothpick

That’s it! You are good to go.

Begin by pouring milk in the pan. You don’t need to take too much of it, just enough to cover all ends of the pan and to ensure that when you drop the dishwash liquid, the milk can float about to get the required results.

Drop food colouring into the milk at random places. We used green, yellow, red and blue.

Now this is not exactly how it looks, my green seems to have been too liquid and it spread as soon as it was dropped into the milk. The colours should otherwise be just blobs as you drop them on the milk at random places, like the blue or the red that you see here. You can drop the colours maybe with a pipette or even a spoon.

Now take a tooth pick, dip it in the dishwashing liquid and touch it on the surface of the food colour.
And be prepared to be amazed!

The effect is so sudden and dazzling you might actually catch yourself gasping in surprise. The colour shoots off all around the moment the colour meets the liquid.

Howzzat! Speechless, aren't you? :-) Check this one!

Doesn't this look or remind you of beautiful modern art paintings? Its an absolute riot of colours.. colours literally bursting in front of your eyes all around an epicentre, ie. the point where the toothpick meets the milk. :-)

Keep doing the same with all the food colouring bits and soon there will be a spectacular mish-mash of colours. It is a sight to watch, really.  You even end up making new colours - orange and sky blue in the picture above and pink in the picture below.

I'm attaching a video just so you know the effect of the bursting of colours.

You can just keep going on and on at it till there is no sight of the milk. The colours will finally end in a muddy brown and there will not be any more colour bursts.

Again, I would like to mention that there is a definite wastage of precious milk, so you can take a small dish if that bothers you enough to not want to try the experiment. But all said and done, the spectacle can be best appreciated by all in as wide a pan as you can manage. :-)

The science behind it is simple – the swirling of the liquid is a result of the detergent disturbing the surface tension of the milk. The food colour is to create the colour effect to fascinate your curious little one’s growing mind.

I waited for A to ask me any kind of questions about this, but there were none forthcoming. I tried nudging, by asking her why does she think this happened. All I got was a disinterested shrug, the 'why-don’t-you-let-me-enjoy-this?' kind of shrug. So, I left her alone to enjoy herself  :-)