Image of a hand under purple light.

Our hands can be pretty gross.

Washing your hands is important, but how do you know if it’s working? Make some safe but gross glow germs to find out how well you wash!

hazard iconhazard iconSafety: Never look directly at a UV torch, and only keep it on as long as necessary. If you have sensitive skin, you might want to try this activity on a small area of skin first, to make sure you don’t have a reaction to sanitiser or highlighter ink.

You will need

  • Small bottle of hand sanitiser
  • Yellow highlighter (non-toxic)
  • Pliers
  • UV torch
  • Dark room
  • Phone camera
  • Basin
  • Soap
  • Running water
  • Clean towel
  • Someone to help

What to do

  1. Take the lid off the hand sanitiser bottle.
  2. Using pliers to pul the felt tip out of a highlighter pen.Carefully use pliers to pull the tip out of the highlighter. If you’re finding it difficult, ask an adult for help.
  3. Putting the felt tip of the highlighter into the hand sanitiser bottle.Put the highlighter tip into the hand sanitiser, and then put the lid back on.
  4. Give the bottle a shake. The ink will start to spread through the liquid.
  5. Bottle of yellow liquid.Leave the bottle overnight to get as much ink as possible into the hand sanitiser. This is now your bottle of pretend glow germs.
  6. Go to a dark room. Get your assistant to shine the UV torch at your hands.
  7. Squirting green flourescent liquid from a bottle onto a hand.Pour a teaspoon of germs onto your hands – it should glow under the UV light! Spread the liquid so your hands glow evenly.
  8. Wait for a minute or so for your hands to dry.
  9. Hands with glowing marks on them.Get your assistant to take a photo of your hands glowing.
  10. Go and wash your hands as you normally would.
  11. Come back to the dark room and look at your hands under the UV light again. Did you get rid of all the glow?
  12. Hands under purple light with small amounts glowing.Take a photo of your washed hands under UV. Compare the new photo with the photo before you washed your hands. What do you notice?

What’s happening?

Our hands can be pretty gross. They touch all kinds of things every day, from door handles to bus seats. We even use them to touch other people, like when we shake hands. And all this touching means our hands pick up germs that are smaller than our eyes can see: bacteria, viruses and microbes.

For many microscopic critters, your hands are a pretty good place to hang out. There’s dead skin to eat, sweat to drink, and it’s nice and warm.

Most of the things living on your skin are harmless, and some are beneficial. But a few are dangerous, particularly if you make it easy for them to get in your body. And you do that more often than you think, such as by picking up food then eating it, touching your face, and scratching.

The best way to keep yourself safe from nasties is to clean your hands. Key times to wash include before handling food, and after using the toilet, blowing your nose, touching a pet, or gardening.

In this activity, you might have noticed there are parts of your hands that are hard to clean. This includes crevices under fingernails, in joints and lines, and between fingers. It takes a lot of care to clean it all properly!

The Food Safety Information Council have four tips for good hand washing:

  1. Wet your hands and rub together well to build up a good lather with soap for at least 20 seconds and don’t forget to wash between your fingers and under your nails. You might have to use a nail brush.
  2. Rinse well under running water to remove the bugs from your hands.
  3. Dry your hands thoroughly on a clean towel for at least 20 seconds. Touching surfaces with moist hands encourages bugs to spread from the surface to your hands.
  4. If no running water is available use alcohol gel.

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4 responses

  1. Ludwika Forster Avatar
    Ludwika Forster

    Love this experiment. Will attempt to do with our six year old. Thank you!

  2. Walter Kuehhirt Avatar
    Walter Kuehhirt

    I did not understand step 7 :”pour a teaspoon of Germs onto your hands”
    How can there be germs in a liquid that kills Germs?

    1. David Avatar

      Sorry for the confusion!

      you’ll see in the fifth step that we’re pretending the UV dye is made of germs. Just a metaphor to make the rest of the activity make sense!

  3. Yvette Cotter Avatar
    Yvette Cotter

    I had to think about this too, I have studied Microbiology and we did an experiment on transferring germs from one to another. This is a demonstration of where germs might congregate. THe hand sanitiser is sterile but contains the fluorescence that sticks to your skin like germs do when you touch things.

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