DIY: Rainbow Bottle | Tinkerer Box Blog

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Rainbow Bottle

Stem Activities

Ages: 3-5

Less than 30 minutes

Grownup needed

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Can salt water create a rainbow? By mixing different amounts of salt with red, yellow, and blue water, then carefully pouring them into a cup, you can witness magical rainbow layers appear!

Materials Needed

4 glass bowls
Salt
Teaspoon
Clear bottle
Straw
Measuring cup
Water

Laid out on a light wood-grain table are several items, seemingly for a craft or science project. These include a clear plastic bottle partially filled with water, a small bottle of blue liquid, a folded piece of clear plastic sheeting, a small clear measuring cup with a small amount of liquid inside, and a pair of blue-handled scissors.

Step-by-step tutorial

Step 1

Add 250ml of water to each of the four bowls, then add different food colourings and stir well.

Two hands are shown cutting a piece of clear plastic sheeting with a pair of blue-handled scissors. The sheeting is gathered and held by one hand while the other hand operates the scissors, cutting through the plastic against a light wood-grain background.

Step 2

Arrange the four bowls of coloured water in order from 1-4. Using a measuring spoon, add 1 teaspoon of salt to bowl 1, 2 teaspoons to bowl 2, 3 teaspoons to bowl 3, and 4 teaspoons to bowl 4. Stir until all salt is dissolved. You now have 4 bowls of salt water at different concentrations.

Two hands are shown pouring liquid from a small, clear measuring cup onto a piece of clear plastic sheeting. The sheeting is held taut between the hands, and the liquid is being poured onto its center. The background is a light wood-grain surface.

Step 3

Pour 50ml of the solution with 1 teaspoon of salt into the clear bottle.

Two hands hold a small, clear plastic pouch filled with a clear liquid. The pouch is tied off at the top with a knot, which one hand is pinching and twisting. The background is a light wood-grain surface.

Step 4

Place the straw at an angle into the bottle.

A hand holds a small, clear, water-filled plastic pouch tied at the top. A pair of scissors is positioned to trim the excess plastic just below the knot. The background is a light wood-grain surface.

Step 5

Through the straw, pour 50ml of solutions 2-4 in sequence.

A hand pours a vibrant reddish-orange liquid from a clear measuring cup into a clear plastic bottle. A white, straw-like object is positioned inside the bottle's opening, guiding the liquid's flow. In the background, several cardboard boxes are stacked, each featuring colorful labels with images that suggest they contain science experiment materials. A piece of light blue cloth is partially visible beneath the bottle. The video showcases the process of preparing a science experiment, likely involving colored liquids.

Step 6

Let the bottle rest for 5 minutes, then pick it up. The different coloured salt solutions haven't mixed - try gently shaking the bottle to observe what happens.

A clear glass bottle is filled with liquids layered to resemble a rainbow. The distinct horizontal bands of color, from top to bottom, are red, orange, yellow, green, blue, indigo, and violet. The bottle is gently rotated, causing the colorful liquids to swirl and mix slightly at the interfaces between the layers. This visually appealing demonstration likely illustrates the concept of liquid density or layering liquids based on their different properties.

The Science Behind It:

The density of a liquid determines its weight. Water with more salt is heavier and sinks to the bottom, while water with less salt is lighter and floats on top. When you carefully pour in coloured salt water of different densities, they don't mix immediately, creating beautiful rainbow layers!

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