Mortise lock

A mortise lock is one which requires a pocket, or mortise, to be cut into the door, cabinet door, or piece of furniture into which the lock is installed. Typically mortise locks have been used on older buildings before the advent of bored cylindrical locks, but in more recent times they have become a staple of commercial construction and higher end residences.

The parts included in the typical mortise lock are the lock body (the part which is installed inside the door); the lock trim (which may include any number of different designs of knobs, levers, handle sets and pulls); and the keyed mortise cylinder which operates the locking/unlocking function of the lock body.

Installation of the mortise lock cannot be done practically by the average home owner since it is labor intensive and requires a working knowledge of basic woodworking tools. Many installation specialists utilize a mortising jig which makes the actual cutting of the pocket a precise operation, but the subsequent installation of the external trim may prove to be problematic if the installer is inexperienced.

Although the installation of the mortise lock actually weakens the structure of the door, it does offer more versatility to the external trim and to the functionality of the lock. Where the common bored cylindrical lock lacks the architecture required for ornate or solid cast knobs and levers, the mortise lock can accommodate heavier return springs and more solid internal mechanisms to make this possible. Further, the mortise lock will commonly accept a wide range of other manufacturers' cylinders and keyways so that it may conform to existing lock hardware on site.

Some of the most common manufacturers of mortise locks in the United States are Baldwin, Emtek, Schlage, Sargent, and Corbin. Also, many European manufacturers which had been restricted to the designer-type installation have gained wider acceptance and use.