Yep, chalk dust!

Professor Kyoto was an old school teacher and used a blackboard and chalk to teach her students, as a result, she had a drawer full of chalks and the dust they drop. Picking up a good handful of chalk dust she quickly threw it at Melissa's face.

"Ah, my eyes!" Screamed the naked heroine as she was temporarily blinded by the chalk. Professor Kyoto quickly went to a hidden drawer and pulled out a rag that she quickly soaked with chloroform and smothered the helpless teen with it, Melissa was unable to fight off the effects of the **** and promptly collapsed.

Locking her door and putting a 'Do Not Disturb' sign on the handle, Professor Kyoto strapped Melissa back into the bindings she'd stupidly let her out of. After a good fifteen minutes, Melissa groggily woke up, the chalk dust having been washed out by Professor Kyoto. Making sure Melissa was watching, Professor Kyoto reattached the Mind Sifter back onto Melissa's head.

"This time you won't escape, just to make sure I inserted a negatonium buttplug, a gift from Dr. Bluder. I now know who you truly are. Rocketgirl!"

Melissa tried to deny it but she knew that she was screwed.

"W-What are you gonna do to me?" Melissa asked, afraid of the answer.

"You'll find out, when you wake back up!"

"WAI-MMMM!" Melissa barely had chance to speak before Professor Kyoto was covering her mouth with an ether-soaked rag.