How to Fix a Groove in the Interior Bedroom Door

Remove the door from its hinges, starting at the bottom hinge and working to the top.

Unscrew any hardware from the door -- and use painter's tape to protect any parts of the door you don't want to paint, such as glass.

Lay the door on two sawhorses.

Clean the door with trisodium phosphate, using a sponge or rag. Rinse with plain water and dry with a towel. Trisodium phosphate removes any sticky residue or dirt on the door, giving you an unmarred surface to work on.

Mix a filler putty according to the package instructions. Many putties are ready to use straight out of the container, but some need stirring. Use a putty designed for the type of door you're working on. For example, use wood putty for wood doors and fiberglass putty for fiberglass doors.

Scoop some putty out onto a putty knife and work the putty into the groove. Ensure the putty goes all the way to the back of the groove for a strong fix.

Smooth the surface of the putty -- so it's flush with the door -- by running the blade of the putty knife across it and scooping off any excess.

Allow the putty to dry completely. This usually takes at least one hour, but follow your manufacturer's instructions.

Sand the surface of the putty with 100-grit sandpaper so it's smooth and blends with the door. If you used a putty that matches your door, you can finish the job here.

Sand the entire door with 100-grit sandpaper to give it some "tooth" for refinishing. Dust with a tack cloth.

Apply a primer to the door using a sponge roller or paintbrush. Use a primer designed for the type of door, such as wood primer for a wood door. Acrylic, water-based primer is a durable and flexible option for doors. Use an exterior-grade primer for exterior doors. Allow the primer to cure.

Paint the door with a water-based acrylic paint in your desired color. Use a paintbrush or sponge roller. You do not need to paint the edges of the door, because they aren't visible when the door is closed. Allow the paint to cure, then apply a second coat.