Introduction: Pour Your Own Rainbow!

About: What you WILL find in my Instructables: food, crafts, crochet, foraging, and much more. What you WON'T find in my Instructables: heavy machinery, tech-related projects (I'm just not very good with computers :(…

Learn how to make use of density properties and pour a rainbow in a cup, jar, or glass for a cool effect and gorgeous room decoration!

Step 1: Things You Need

Here are the things you will need to try this at home:

  • 4 Clear cups or containers
  • Food coloring in Red, Yellow, Green, and Blue (I used gel but liquid is a better choice)
  • White Sugar
  • Syringe
  • Warm water

Step 2: Prep Your Liquids

1. Number 4 cups 1-4 with a marker

2. Pour 1 spoonful of sugar in cup 1, 2 spoonfuls in cup 2, 3 spoonfuls in cup 3 and 4 spoonfuls in cup 4

3. Pour in 60ml of warm water in each cup and lightly stir to dissolve To help the dissolving process, put cups in the microwave and microwave for 30+ seconds and then stir each one again.

5. Color the liquid in cup 1 red, yellow for cup 2, green for cup 3, and blue for cup four (one drop of liquid food coloring, I simply stirred in some gel coloring for mine)

Step 3: Layering the Colors

1. Take your syringe and fill it up with the blue sugar water (cup #4). Gently squeeze drops of it into the bottom of your cup or container

2. Then repeat with your other colors in order from blue, green, yellow, and lastly red.


NOTE: When I first tried this experiment, I failed many times. Each time the water would become brown as all the colors mixed together. I slowly figured out that the trick was to squeeze slowly, releasing drops of the liquid and also holding the syringe close to the surface of the liquid in the cup.

Step 4: Analysis: What Happened and Why?

So, why did the colors not mix together?

Because the densities of the different colored liquids were different! Density of a substance is the ratio of its mass to it's volume. The blue liquid had 4 teaspoons of liquid and was the densest compared to the other 3 liquids. This means that it will stay at the bottom even when other liquids are poured on top. This applies again with the other 3 colored liquids. Have you ever tried to mix oil and water? You would probably know that they do not mix, because the oil is less dense than the water and so it is on top.

To add different colors, simply play around with the amounts of sugar in the liquid to change up the density. More sugar = higher density.

Step 5: Gallery!

As you can tell, the one I did in the light bulb bottle did not turn out as well, I think this is because I had to do a lot more liquid and the chances were much higher that the colors would mix.

Explore Science Contest 2017

Participated in the
Explore Science Contest 2017