Glowing Water

Glowing Water

Make water glow eerily under a black light using the fluorescent dye found in highlighters. Glowing water can create some exciting special effects when used in fountains, or use it to transfer glow to bubbles, ice and slime.

Suitable for kids aged 8 + with parental supervision

CAUTIONThis science activity involves the use of a sharp knife to cut open a highlighter pen and the ink-soaked felt inside the highlighter. This must only be done by an adult.

You Need:
  • Yellow highlighter felt pen
  • UV light, or black light
  • Gloves
  • Clear glass or container
  • Water
What to do:
  1. Prise off the back of a highlighter pen, or if this is not possible, have an adult carefully cut the pen in half with a sharp knife.
  2. Pour some tap water into the glass or container.
  3. Wearing the gloves, pull out the ink-soaked felt that is inside the cut pen. Although nontoxic, the gloves will protect your fingers from being stained with the fluorescent dye.
  4. Soak the felt in the container with water for an hour or so. With the gloves on, squeeze the felt until almost all the ink has been transferred to the water.
  5. Turn on the black light and watch your water glow an eerie green.
  6. Use the water to transfer glow to any water based experiments or activities, like making slime, ice or bubbles. Tonic water also glows under UV light, so is great to use in edible glow experiments, like making glowing jelly.

Why is it so?

Tonic water and highlighters glow under black light because they contain fluorescent chemicals. These chemicals absorb light and then release it back. In this case they absorb highly energetic invisible UV light and release less energetic but visible light. The water is transparent so it is easy to colour with these glowing chemicals. The glowing water can be reused again and again and will never lose its glow.