When Albus was young, he went to Cairo for an alchemy competition, but competing was not his only reason for going.
Pomona leafed through the notes he had left behind. One day, while wandering through Cairo's pigment market, he discovered dragon blood for sale, even though Muggles frequented the market.
The vendors would boast to their customers about how a bottle of blood was connected to stories of saints, princes, princesses, and great beasts. They did it only to raise the price, and the customers knew their tricks perfectly well. Not every bottle contained "dragon blood."
Perhaps to prove that he knew what he was looking at, or perhaps out of youthful impetuosity, Dumbledore bought a bottle too. He was swindled, and from then on, he became interested in studying dragon blood.
Slughorn had once used dragon blood in a Muggle home to fake the appearance of having been attacked. Dragon blood, like wizard blood, retained traces of magic, while Muggle blood did not.
People had always focused on dragon blood's uses in potions. Dragons were powerful creatures, after all, so their blood ought to have potent healing properties. But Albus discovered that dragon blood could clean a fireplace and remove stains as a detergent, because he had once used it that way while doing housework in his youth.
When his paper on the twelve uses of dragon blood was first published, people would almost have dismissed it as a joke if not for the fact that he was the Hero who had defeated Gellert Grindelwald.
The ash in a fireplace consisted mainly of grease and plant ash, both of which dragon blood could dissolve. Pomona used this property of dragon blood to brew the potion the maze required.
Though all were dragons, Welsh Green Dragon blood, Hungarian Horntail blood,