Science Fun with Food Colouring and Dish Soap

If you would like to make this concoction start with a cookie sheet and add enough milk to cover the bottom. Thank you to Hands On: As We Grow for the idea.

Add a few drops of food colouring.

Add a drop of dish soap.

This is what happens.

I was very excited, never having done this experiment before and yelled out “the food colouring is running away from the soap!”. So much for allowing Daisy to draw her own conclusions!

Daisy enjoyed moving the milk and watching the green move further from the center of the pan.

Add another few drops of food colouring and then dish soap.

And again.

The movement is not as dramatic (luckily neither was I) as that first drop of dish soap but it was still fun to add more colours.

Here is the science bit:

Dish soap is a ‘degreaser’ that attacks the fat molecules in the milk. The movement of the molecules breaks the surface tension of the milk and the food colouring simply lets you see that movement.

We did try to make a print of the beautiful pattern created but the coffee filter we used, welded itself to the dinner plate it was drying on. Any suggestions for how to capture the art?


  • Add all the food colouring at the beginning
  • If you get excited by science do it by yourself first so you can enjoy your student’s reactions!

Learning Opportunities:


  • Hypothesize about what may happen.
  • Investigate chemical reactions
  • Discuss results and reasoning

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