All of the following are steps for proper instrument care EXCEPT

Keep instruments with differing finishes separate.
Use the instrument only for the purpose for which it is designed.
Keep ratcheted instruments in a closed position.
Do not stack instruments to avoid entangling them.

Keep ratcheted instruments in a closed position.

Rationale: If ratcheted instruments are not open during the sterilization process, surfaces not exposed to the sterilant will remain contaminated.