(Left) Colorful, soft,rounded, happy-looking cartoon things can be painted or thinned. (Right)Dark,pointy, dangerous-looking inert things can't.

An obstacle/enemy's State of Matter decides if Mickey's Paint and Thinner affect it or not. In Epic Mickey, there are two states of matter.
  • Toon- These obstacles can be erased or painted in.
  • Inert- These obstacles can't be erased, and Mickey's paint has no effect on them.

Beetleworx are made of both substances. Mickey has to thin out the Toon shell and attack the vulnerable Inert core.