Cauldrons are items in the form of large pots that witches use to make potions. These items contain the magical energies resulting from the brew and the chemicals used to create it. These magical energies can seep into the cauldron over the course of numerous generations. As the pots absorb the runoff of numerous potions being brewed in them, they ultimately become magical themselves. This makes the potions made within them more powerful and potent, with the cauldron adding its own power to the contents of the brew. This makes the oldest cauldrons incredibly valuable to witches, with these items being passed down to each generation over hundreds of years through a coven.
Newer cauldrons lack the history and usage of these ancient cauldrons, and lack the slow buildup of magic that their counterparts have developed over the centuries. As such, they are just normal pots used as containers for brewing potions. However, potions that are made within recently built cauldrons brew faster, making the process of potion making quicker. This has led to a competing market where cauldrons can be bought and sold, dependent on the potential needs of an individual. However, the situation seems counter-intuitive. If older cauldrons have built up magic over many centuries, it stands to reason that brewing potions within them would speed up the process and make it more powerful, with the cauldron adding its own magic to the potion and maxing it up. As it turns out, a cauldron that isn't magical at all due to its recentness is more likely to win out in this regard. How can this be the case?