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I have read when i was in fourth grade that onion juice could be used to make invisible ink that appears when the paper is heated. There was also a scene[0] in
by ducaale 7y ago
I have read when i was in fourth grade that onion juice could be used to make invisible ink that appears when the paper is heated.
There was also a scene[0] in National Treasure film (2004) where they use lemon and heat to reveal a hidden text
[0] https://www.youtube.com/watch?v=WTA7KR9-9lM https://www.youtube.com/watch?v=WTA7KR9-9lM
- JulianMorrison 7y agoSoya juice (what she used) probably has the advantage of not smelling. Onion and lemon would give themselves away, I feel!
- alexis_fr 7y agoIt looks like any organic liquid works, including milk in the case of Lenin, soya juice in your case, lemon and onion if you want to tip off the spied ;) I’m curious about how it bends the paper. The retractile nature of drying juices must create visible irregularities on the surface.