How to Open a Mortice Lock

Written by anne redler
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How to Open a Mortice Lock
A mortise lock is excruiatingly hard to open without a key. (lock image by Gonçalo Carreira from

A mortise lock comes in many shapes and sizes although the basic mechanics of the lock include a lock body, with a bolt, that is mounted into a door, window or piece of furniture and a fitting that accommodates the bolt and is fitted into the opposing frame. The door knob and keyhole for the lock are embedded in the lock body and a key is required to lock and unlock the door, window or piece of furniture with this type of locking device.

Skill level:


  1. 1

    Insert the matching key into the mortise key hole. Insert the key all the way so that it cannot be pushed in the key hole any farther.

  2. 2

    Turn the key counter-clockwise by one half to one full turn, depending on the model, to force the bolt to slide to the left from its locked position.

  3. 3

    Listen closely to make sure the bolt retracts into the body of the lock from its fitting in the door frame. You'll hear a "click" when this occurs. If the bolt does not unlock, jiggle the key in the keyhole and try the previous step again.

  4. 4

    Turn the door knob counter-clockwise, if applicable for that particular mortise lock fitting, or push down on the door handle for other models.

Tips and warnings

  • Older mortise locks can be more difficult to open versus new mortise-lock models.

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