Colourful Milk Display

A simple science activity that creates stunning colour explosions using whole milk, food colouring, and dish soap. The reaction between the dish soap and the fat molecules in the milk scatters the food colouring, producing a vivid swirling display. This activity can also be used to introduce kids to the concept of emulsions.

What You'll Need

• Whole milk (at least 1 cup)
• Shallow tray or plate
• Food colouring (assorted colours)
• Pipette or dropper
• Washing up liquid / dish soap

Steps

1. Pour a layer of whole milk into the shallow tray or plate.
2. Gently drip a few drops of food colouring onto the surface of the milk, spreading them out across the surface.
3. Add a few drops of dish soap directly on top of the food colouring drops and watch the colour explosion begin.
4. Observe the colours swirling and spreading as the soap reacts with the fat in the milk.

SAFETY NOTE Do not drink the milk after the activity.

Why Does It Work?

Milk is mainly tiny droplets of animal fat dispersed in water. Whole milk produces the best results due to its higher fat content. The dish soap acts as an emulsifier – it breaks down the fat in the milk, causing the food colouring to scatter and swirl as the fat molecules move. This is the same principle that makes dish soap effective at cleaning greasy dishes.

Extension Ideas

• Try different dish soap brands to compare the effect.
• Experiment with whole, semi-skimmed, and skimmed milk to see how fat content affects the reaction.
• Try adding drops of multiple colours and observe how they interact.

Shot List

• Colour drops on milk surface
• Soap application close-up
• Colour explosion reaction
• Full display overhead shot