Of course, the poison pen is mightier than the dull-edged sword, and I’ve got a micro weapon of mass destruction. I write my manifestos in blood, plot bank jobs in ink black as midnight, but for secrets . . . well, those deserve a lighter touch. Like any clever spy, I like to hide things in plain sight, and invisible ink is just the trick. It is a cinch to whip up, and there are few things more delightful than a scorching-hot love note revealed over the bright flame of a candle.
As kids we made invisible ink using the juice of fresh-squeezed lemons. While practical, the mix doesn’t store well and the ink can be a bit cloudy. This covert concoction is a clear upgrade.
Wide bowl
1 tablespoon citric acid powder (see Notes)
⅓ cup water
Metal-nib caligraphy pen
Light- or normal-weight typing or copy paper (heavy paper is harder to work with)
Small jar with a sealable lid
Candle and matches
1. In a wide bowl, combine the citric acid powder with the water. Stir until the mixture is no longer cloudy.
2. Dip the pen into the ink, pressing the nib down slightly. Write as usual, dipping the pen frequently——every three or four letters.
3. Transfer the ink to a small, lidded jar for storage and later use.
4. To decrypt: Hold the note over a candle flame close enough for the paper to brown but not catch fire——this will take some practice but is lots of fun in itself. It helps to know where the writing is on the paper before decrypting (see Notes).
5. Burn after reading.
Citric acid is found in the canning section at grocery stores, or at health food stores, or online.
Consider making more than one copy of your final draft, in case the original note combusts during decryption (this can happen faster than you might think). Also, keep a glass of water nearby or decrypt next to a sink, just in case your writing becomes especially volatile.