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Floating images

By David, 21 March 2019 Activity

Drawing of a green and red butterfly in the bottom of a bowl with a small amount of blue water.Have you ever wanted to bring your pictures to life? Here’s one neat trick to make a drawing float away, literally!

You will need

  • Small bowl*
  • Non-toxic whiteboard markers
  • Tablespoon
  • Water

* Hint: The activity works best if the bowl is quite new, without cracks or scratches.

What to do

  1. Drawing a butterfly on the inside of a white bowl.Draw a small picture in the bottom of the bowl with the whiteboard markers.
  2. Pouring blue liquid into a bowl with a butterfly drawn on it.Tilt the bowl to the side and add about a tablespoon of water, away from the drawing.
  3. Bowl with blue liquid and a butterfly. Corner of butterfly is floating on liquid.Slowly tilt the bowl back so the water starts to touch the edge of your drawing. The marker ink will start to float up to the surface of the water.
  4. Keep tilting the bowl, carefully floating the drawing bit by bit.
  5. Butterfly drawing in a bowl of blue liquid.When it’s completely floating, you can move the drawing around by gently shaking the bowl, by blowing on it, or by poking it very gently.

 

What’s happening?

Whiteboard marker ink has three main ingredients. Pigments give the ink colour and solvents keep it liquid inside the pen. The third ingredient is a resin, which is need to make this activity work.

Whiteboard marker resin is an oily solid, which sticks lightly to whiteboards. Inside the marker, the resin is dissolved in the solvent chemicals. After you’ve drawn a line, the solvents quickly evaporate and the resin turns back into a solid.

When you add water to the bowl in this activity, you start a struggle. The resin sticks to the bowl like it would a whiteboard. But it also sticks to the surface of the water. The attraction force of the water surface, known as surface tension, is strong enough that you can use the surface of the water to peel the marker off the bowl.

Surface tension is surprisingly strong. In a recent experiment, scientists from the United States and France used surface tension to peel permanent marker off a sheet of glass!

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