Abstract: An apparatus and method are used for preserving a mortise. A guard for preserving a mortise includes an overlay configured to fill the mortise, an edge conforming to an indentation edge of the mortise, and a securing device configured to removeably attach the overlay within the mortise. The guard may further comprise a flange disposed on the overlay for placing and removing the guard from the mortise. The securing device may be configured for receiving a fastener or may include a protrusion configured to be received in a hole disposed in the mortise. The guard advantageously prevents paint from entering and damaging the mortise. A method for preserving a mortise includes providing a guard configured to fill the mortise, placing the guard on top of the mortise, and securing the guard within the mortise. Beneficially, the guard and method for preserving a mortise protects a mortise from exposure to paint.