This means no big, ugly stamp marks on your hand and no more free admission for anyone trying to sneak in. Light-activated inks work because they contain substances that glow under different types of light, but remain invisible to the naked eye. When you return to the park, they will ask you to put your hand under a special light, and just like magic, a glowing stamp imprint appears. If you need to leave the park, they will stamp your hand, but you may be surprised when you look down to find nothing is there.
Today, many amusement parks use light-activated invisible inks. These ink stamps were easy to copy and allowed people to sneak in without ever paying for a ticket.
When you returned to the park gate, as long as you had the stamp, you didn't have to pay to come back inside. Long ago, if you needed to leave an amusement park to go to your car, they would simply stamp your hand. Vinegar alone can be heat-activated, but if you add red cabbage water instead of heat, it becomes a chemically-activated invisible ink.Ī third kind of invisible ink is a favorite of amusement parks. When the message receiver adds the second chemical developer, the chemical reaction between both substances causes the color to change and the message to appear. Chemically-activated inks can be made from any two chemical substances that are colorless until mixed with one another. You can find many heat-activated invisible inks right inside your kitchen, including clear soda, lemon juice, apple juice, onion juice, milk, soapy water, sugar water, and vinegar.Īnother type of invisible ink is chemically activated. When the ink is exposed to heat, such as under an iron or over a candle flame or 100-watt light bulb, the acids in the liquid turn a different color and the message becomes visible. Once the message dries on the paper, it is invisible. These inks can be made from many types of organic liquid. One very simple form of invisible ink is heat activated. One way to do this (and answer the challenge) is to use invisible ink. What do you think? How would you answer the challenge? It can be fun to think like a spy and figure out ways to send secret messages. Your challenge is to leave a written message on a piece of paper in a way that people won't see the message, even if they stare right at it. ATTENTION, SECRET WONDER AGENTS: Today's Wonder, should you choose to explore it, is one of great mystery…and science.
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