March 4th, 2024

Science Smarts: Magic milk for you know who

By Patty Rooks on December 23, 2023.

It is almost here, two more sleeps and the big jolly guy will be arriving at our houses! Well, I perhaps should not say that; as he will only come to your house if you have been nice NOT naughty – do not forget that, as there is still time for him to change his mind!! We all know Santa is a pretty special person, so full of magic, wonder and so many cool things. Did you know the milk we leave him to wash all those cookies down with can also be magical? Let’s get started!

*Remember to ask an adult before doing this experiment.


– Homogenized milk

– Cotton swab

– Flat glass baking dish

– Dish soap

– Clean plate or saucer

– Christmas cookie cutter

– Red and green food colouring


1. Set the cookie cutter in the middle of the flat glass baking dish. If you have a large flat glass baking dish put a couple of cookie cutters in!

2. Pour enough of the homogenized milk into the pie plate so that it comes up half way inside the cookie cutter.

3. Place two or three drops of red food colouring (depending on how large the cookie cutter is) inside of the cookie cutter. Squeeze two drops of green food colouring outside of the cookie cutter.

4. Squeeze out about one teaspoon (15 mL) of soap out onto the clean plate.

5. Dip the tip of your cotton swab into the soap.

6. Take the cotton swab and touch the surface of the milk right in the middle of the cookie cutter.

7. Observe what happens.

8. Take a clean cotton swab and dip once again in the dish soap.

9. Carefully touch the surface of the milk outside of the cookie cutter.

10. Observe.

11. Remove the cookie cutter from the flat glass baking dish.

12. Watch what happens.

What is going on?

You had a nice large surface area in your large glass baking dish. This allows for the magic to happen! The science at play here is chemistry. The chemistry of the dish soap and the large fat content in the mild are the reasons for the magic.

The food colouring should have stayed in one circle and not spread out much initially. This is because the food colouring is water soluble and does not mix very well with the high fat content in the homogenized milk.

The surface molecules in the milk will begin to pull on the puddles of colour. They will slowly begin to spread in all directions. By adding the liquid soap, you are weakening the pull of the water molecules in the centre, causing the stronger water molecules on the outside of the container to pull the puddles of colour toward them.

The soap also breaks down the fat molecules allowing the food colouring and milk to mix.

We have a few spaces for our Operation Minerva Conference on Jan. 30. This is open to ALL Grade 9 girls who are interested in STEM. It is a day of STEM with mentoring and hands-on workshops. Send me an email and I will get you an application – NOTE: space is limited!

Patty Rooks, Senior Scientific Consultant PRAXIS, “Connecting Science To The Community”. Contact Praxis at,, Tweet or follow us @PraxisMedHat, or friend us on Facebook. Address: #12 826 11 Street S. E., Medicine Hat, Alberta, T1A 1T7 Phone: 403-527-5365, email:

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