Thanks to their interest in Potions, this fact was something that both Albus Potter and Scorpius Malfoy were aware of. Furthermore, both knew that Pearl Dust burned when exposed to tincture of Demiguise. Using this knowledge, the two were able to send a message from the past using Harry Potter's blanket by writing a message on it with tincture of Demiguise, which would not react until 2020, when it was splattered with Love Potion in an argument between Albus and his father, Harry Potter.
Behind the scenes
- In the U.S. edition of the book featuring the script of the Harry Potter and the Cursed Child play, the name of the ingredient is not capitalised and is given as "pearl dust."