Wednesday, October 08, 2014

Home Made Play #4: Milk Magic

Nope, this isn't a breast feeding post.

It's about cool science. You get to dot milk with pretty colours and then  get the coloured swirls to move around as if they had a life of their own.

All 3 love this experiment though it requires a bit of dexterity and not dunking the entire cotton bud in.

It eventually looks the colour of strawberry, orange or weird green melon milk when they are done with it. But it's cool nonetheless.

All it requires is
a. Food colouring
b. Detergent
c. Full fat milk (The more milk fat there is, the more dispersal effect there will be)
d. Cotton buds

What happens in this 'experiment' is that milk has 'surface tension' that is created by the cohesive forces of milk molecules. Liquid colouring, being less dense than milk stays on the surface, most of the time in the vicinity of where it was dripped. Detergent weakens said surface tension. So when the detergent is dipped onto the colour droplet, it breaks down the fat in the milk and the tension outside of the detergent drop pulls the colouring outwards, forming a colour rim. (See Muffin's right corner picture)

The first time Muffin did it, he simply could not follow the instructions of 'touch the surface of the milk with the cotton bud' and 'use the other end of the cotton bud to dip detergent onto the coloured dot.' He spent his time turning the milk into coloured liquid.

The second time we did it, he was much more conscientious about following instructions. And managed to make some nice patterns before he started stirring it and declaring he was making 'orange' or 'strawberry' tea.

Evan was more fascinated with the effect the detergent caused (true to his curious and slightly more science inclined mind) and would repeat it again and again just to see the dispersal effect while Jordan , true to herself, wanted to make complicated swirls before she dispersed it. She saw that as a means of clearing her pattern so that she could start with a relatively clean milk surface again.

It's not something that will occupy them the whole day but it did keep them quiet for a good while and doesn't cost much to create (I bought home brand milk and used whatever colouring we had left from the cloud dough session) and the added bonus of it being pretty at the same time.

There's more of an explanation here if needed. 


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