Magic Milk

by Deb on November 9, 2012

Do you know how detergent works? If you vaguely remember your senior chemistry, you would know that it is a long molecule, one end is hydrophillic, or water loving, the other is hydrophobic, or water hating. What that means is that one end grabs on to the water molecules, one end grabs on to grease and oil, and when you wash it off it takes the grease with it. Voila, clean dishes.

This can all be a bit difficult to imagine, but luckily we have a way of seeing it in pretty pictures. There is a common household item that contains water, fat, proteins and makes a good canvas – milk. So of course we had to try it.

And being us, we had to test other things as well. We tried water and cream because they represent the ‘pure’ parts of the mixutre – water and fats.

The reason there is a bit of movement with the water is because the detergent disturbs the surface tension, and I suspect there isn’t any movement in the cream because of the opposite – it’s too thick for the food colouring to move around easily. But in the milk the lowered surface tension makes it easy for the water based food colouring to move around, while the end of the detergent writhes and rolls to pick up as much fat as it can.

We were going to do a mix of water and cream to see if we could recreate the milk effect, but moving and living hundreds of kilometres apart got in the way. Wasn’t it nice of us to leave you one to discover for yourselves?

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