an activity from Grow in Wonder
Lemon juice dries clear. Write with it and your words disappear. Warm the page and they come back, brown as toast.
Grandpa Theo says
"A secret is heavy when you are the only one carrying it. Hold it up to the light and it weighs a good deal less."
The page above only pretends. This is the real thing, and it takes about ten minutes plus drying time.
Press the dry page with a warm iron, no steam, a few seconds at a time. Or hold it near an old-style light bulb, the kind that gets hot. Keep the paper moving and never let it touch the bulb.
Energy-saving and LED bulbs do not get hot enough, so nothing will show. Please skip candles and flames altogether.
Lemon juice is mostly water, with a little acid and sugar in it. When the water dries away, what is left on the paper is too thin and pale to see.
Heat changes that. The dried juice turns brown well before the paper does, so your writing shows up while the page around it stays pale. Scientists explain the browning in slightly different ways. Anyone can watch it happen.
People have been hiding words on a page for a long time.
A Greek engineer named Philo described an ink that stayed invisible until a second liquid was brushed over it.
The Roman writers Ovid and Pliny described secret letters written in milk and in the juice of plants.
George Washington's spies hid messages in an invisible ink made by a doctor named James Jay.
More of Ava's world is waiting in the books
See the book series