Been Around A While

Riddle: You don't see me, unless you heat me. You don't smell me, unless you make me. You don't know I'm here, until it's too late. I have seen countless generations, and light parchment always magnifies my presence. What am I?

Answer: Invisible ink.

Source: https://www.riddles.com/6887

You don't see me, unless you heat me. You don't smell me, unless you make me. You don't know I'm here, until it's too late. I have seen countless generations, and light parchment always magnifies my presence. What am I? — Been around a while by JNutt22 v1.

Riddle: You don't see me, unless you heat me. You don't smell me, unless you make me. You don't know I'm here, until it's too late. I have seen countless generations, and light parchment always magnifies my presence. What am I? Answer: Invisible ink. — by JNutt22 v2.