Have you ever wanted to spray paint your own wall? Cannot afford an airbrush or spray paint cans? Fear not. You can use this not-quite-the-same-but-good-enough technique.

First, dissolve some watercolors in a glass of water. Then cut a straw in half. Place half the straw in your mouth and the other half in the water.

The straw in your mouth must be held 1 cm away from the top part of the straw placed in the water. Blow quite hard into the straw in your mouth and the water should rise up through the other straw and be splattered onto the wall. If that doesn’t happen, lower the other straw further down in the water.

Blowing into the straw causes a rapid flow of air to pass over the top of the other straw. This causes the pressure at the top of that straw to decrease, making the water rise from the glass through the straw to be splattered against the wall.

Commercial airbrushes work in the same way but reach higher pressures and finer liquid droplets. For other fun experiments visit www.thenakedscientists.com.