Exhibit: Shadow Box

Stand in front of the ‘shadow’ wall and get someone to press the button on the flash unit.  After the flash, your shadow is still visible on the glowing wall.   The wall is made from plastic containing the same luminous material that makes fire exit signs glow in the dark.  The luminous picture on the sign has to be given some daylight before they will glow.  In the same way, the material on the wall only glows after a strong flash of light falls on it.  If you are in the way, you will cast a shadow on the wall behind you, this means that section of wall doesn’t get its flash of energy, so it doesn’t glow.  Your shadow stays there for a minute or so until the surrounding glow has faded.