Can you please explain 'treated' here?
The word "parchment" is derived from the name Pergamon, a city in ancient Asia Minor, modern Turkey, which was a center of its manufacture. It is treated animal skin, scraped thin and with the hair removed.
"Apply a process or a substance to (something) to protect or preserve it or to give it particular properties" Oxford English Dictionary. com/definition/treat
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
"Apply a process or a substance to (something) to protect or preserve it or to give it particular properties" Oxford English Dictionary.
https://www.lexico.com/definition/treat