Jewish Humor Really Isn't Funny Once YOU Get Their Punchline[s]

https://www.sefaria.org/Mishnah_Niddah.5.4?lang=bi

"I apologize for any confusion earlier. The term "tain" is indeed used in the context of mirrors, specifically for the reflective coating. The "silvering" or reflective coating on the back surface of a mirror is often referred to as the "silver tain" or simply "tain." So, yes, "tain" is the word for the second component, which is the reflective coating on the back of the glass in a modern mirror."
https://chat.openai.com/share/eb3beff3-b2cb-4a74-af73-c31a551ba035