How does disappearing ink work?
What is the chemistry behind invisible ink?
Thymolphthalein is an acid-base indicator commonly used as "disappearing ink." It transitions at around pH 10. Below this pH, it's invisible, but above this pH it's blue.
Sodium hydroxide (very basic) is added to thymolphthalein to keep the ink blue, but CO2 from the air neutralizes the ink and it becomes colorless. If something basic is added to the secret note, it becomes blue (and visible again!)
by world of the wise8 years ago
I know its hard to know you have run out of invisible ink but lets assume the invisible ink is still available...How do you read the notes you have written with it?
by Marlene Bertrand4 years ago
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by Catherine Spinola5 years ago
Do you prefer to write with black or blue ink, or do you not have a preference?School will begin soon and many will be purchasing school supplies. When you buy pens do you buy a pack of blue or black ink, or...
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