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What is a Finish Plate?

Alexis W.
Alexis W.

A finish plate is a protection method for the inner workings of a mortise-style lock within an entry door. The plate is used to both conceal and protect the screws and moving parts of the lock from outside elements and potential thieves. The finish plate for locking systems is typically fashioned out of hardened steel or stainless steel. Often, the finish plate has an aesthetic technique applied to it, making it functional in residential entry doors without giving an industrial appearance.

Without the finish plate applied, the workings of the mortise locking system become vulnerable to harmful elements. They also become susceptible to potential burglars or thieves. The components would otherwise be visible, allowing thieves to be able to manipulate the lock components to gain entry.


A mortise lock is a locking system housed in a casing that is directly set into the mortise that has been cut or drilled into the door’s leading edge. It is placed directly opposite of the hinge side. Since the mortise lock is contained within the casing and then applied to the door as a whole, the operation that allows the lock to function becomes vulnerable without the application of finish plates, which are used to conceal and cover the set screws for the operation as well as to finish the installation by forming the armored casing for the door opening.

Finish plates are attached to the underplate through the use of set screws or cylinder screws. The screws are machined to tighten into the hidden side of the finish plate so that the finish plate is not accessible from the outside of the door. The steel that finish plates are typically fabricated from is formed in a manner that prevents the bending or contortion of the plate, so no one is able to get to the mortise lock inside.

Finish plates are a key deterrent for people who would otherwise attempt to enter the premises through the manipulation of the locking mechanism. Typically, the finish plate is also contoured in a fashion that makes it even stronger because of its shape. Typically, it requires an extreme amount of force to negate the finish plate to gain entry through means other than the key.

Mortise locks have become more popular in residential applications. Their popularity has grown because they have become more appropriate for residential settings as finish plates allow for more aesthetic manufacturing methods. They have, however, been utilized in industrial and commercial settings for quite some time.

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