How to Paint on Milk?

Have you ever thought to paint on the milk? Amazing idea. isn’t it. And today, we gonna show you this amazing science experiment with the material you can find in the kitchen. Trust me, you can be an artist if you really try this one.

Age：3+          Time: < 15mins

 Safety 

1. Do not drink the milk in this experiment.
2. Be careful, not to break the chinaware.

 Materials list 

• 100ml whole milk
• Food coloring (red, yellow, green, blue, any colors which you think can create a fabulous painting)
• Dishwashing soap
• Dropper
• Plate (transparent cup)

 Instruction 

Step 1/3 – Pour the milk to the plate, about 5mm depth.

Step 2/3 – Add a few drops of different food coloring in the milk.

Step 3/3 – Soak a cotton swab with washing liquid and draw on the milk. Then, you can see the food coloring running on the milk.

 Troubleshooting 

Why does the food coloring dissolve quickly in milk?

- The food coloring used in this experiment can dissolve in water with ease so the lower the fat content in milk, the more food coloring will dissolve in water. Therefore, when skimmed milk or low-fat milk is used, the food coloring will dissolve quickly and fail to achieve the desired effect.

 Question to ask 

1. You can use soy milk, coconut milk as well as goat milk to do this experiment.
2. What will happen if other kinds of liquid are used to replace the milk?

 Scientific description 

The principle behind is the Surface Tension Theory. The main ingredients of milk are water (mostly), protein, fat, vitamins and, etc. Because some proteins and fats in milk cannot dissolve so they remain droplets in the water. The dishwashing soap can significantly reduce the surface tension. When dishwashing soap is added to the milk, it reduces the surface tension of the water so the milk made by the protein and fat in the milk will flow, while the food coloring on the surface will flow with them too. Thus, the color is moving.

 Extensions 

Use a cotton swab to dip some washing soap and paint on the milk.

 Disposal 

Pour the milk into the sink and do not forget washing what you have used.