Activity #3 - Stainless colour soap bubbles

Difficulty: Easy
Time Required: Only Takes a Few Minutes

Here's How:

  1. If you are making your own bubble solution, mix the detergent and water.
  2. Add the sodium hydroxide and indicator to the bubble solution. You want enough indicator so that the bubbles will be deeply colored. For each liter of bubble solution (4 cups) this is about 1-1/2 to 2 teaspoons of phenolphthalein (red) or thymolphthalein (blue).
  3. Add sodium hydroxide until you get the indicator to change from colorless to colored (about half a teaspoon should do the trick). A little more sodium hydroxide will result in a bubble that stays colored longer. If you add too much, the color of the bubble won't disappear when exposed to air or rubbed, though you can still react it with club soda.
  4. You may find it necessary to dissolve the indicator in a small amount of alcohol before mixing it with the bubble solution. You can use pre-made indicator solution, adding the sodium hydroxide to the indicator rather than diluting with water.
  5. You've essentially made disappearing ink bubbles. When the bubble lands, you can make the color vanish by either rubbing the spot (reacting the liquid with air) or by adding a little club soda. Fun!
  6. If you have disappearing ink, you could mix it with bubble solution to make disappearing ink bubbles.


  1. Please don't drink the bubble solution! Unused bubble solution may be stored for later in a sealed container or disposed of by pouring it down the drain.
  2. These are bubbles intended for 'blowing bubbles', not for bathing.
  3. Sodium hydroxide is a strong base. Avoid direct contact with this ingredient. If you do get some on your hands, rinse them immediately with water.
  4. Phenolphthalein and thymolphthalein change from red or blue to uncolored around pH=10. If you look on the indicator chart, you can see there are several less common indicators that would change color rather than disappear at this pH.

What You Need:

  • Liquid Dishwashing Detergent (or other detergent)
  • Water
  • or Commercial Bubble Solution
  • Sodium Hydroxide
  • Phenolphthalein
  • Thymolphthalein
  • Club Soda (optional)

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