How to Prep Interior Doors for Painting: Sanding and Priming (Step-by-Step Guide)

Proper preparation is the most important part of painting interior doors. Good sanding and priming prevent peeling, ensure better paint adhesion, and deliver a smooth, professional-looking finish.

Skipping these crucial steps often leads to visible brush marks, uneven paint coverage, and doors that need repainting soon. This guide walks you through exactly how to prep your interior doors correctly.

• 120-grit and 220-grit sandpaper (or sanding sponge)
• Tack cloth or microfiber cloths
• Mild detergent or degreaser
• Wood filler (for damage repair)
• High-quality interior primer (stain-blocking recommended)
• Painter’s tape
• Screwdriver
• Drop cloths
• Vacuum with brush attachment (optional)

You have two main options:

1. Remove the door: This gives the best results because you can paint both sides easily and avoid drips.
2. Paint the door in place: This is faster but requires more care to protect floors and hinges.

Most professionals recommend removing the door and placing it on sawhorses for easier sanding and priming.

Remove the doorknob, hinges, and any locks. Take a photo of the hardware layout before removing it to make reinstallation easier.

If you prefer not to remove the door, cover the hinges and hardware carefully with painter’s tape.

Clean the entire door, including the top edge (which collects a lot of dust) and both sides. Use warm water mixed with mild detergent or a degreaser.

Pay special attention to areas around handles where fingerprints and oils build up. After washing, wipe the door completely dry. Any remaining dirt or grease will prevent proper sanding and priming.

Fill dents, holes, scratches, or cracks with wood filler. Let the filler dry completely, then sand the repaired areas smooth before proceeding.

Sanding creates a smooth surface and helps new paint adhere properly.

• Start with 120-grit sandpaper to remove old gloss, rough spots, or flaking paint. Sand with the grain of the wood.
• Sand the front face, back face, and all four edges (top, bottom, and sides).
• Switch to 220-grit sandpaper and sand the entire door lightly again for a very smooth finish.

For pre-primed doors (most new doors), use only 220-grit or finer sandpaper. Do not sand aggressively, just lightly scuff the surface to help adhesion.

After sanding, remove all dust thoroughly. Use a vacuum, then wipe the door with a tack cloth or a damp microfiber cloth. The surface must be completely dust-free before priming.

When do you need to prime?

• New unfinished or bare wood doors → Always prime
• Pre-primed doors → Usually not needed (just light sanding)
• Changing from dark to light color → Strongly recommended
• Painting over oil-based paint with latex paint → Prime required

Apply a high-quality interior primer. Use a brush for panel edges and recessed areas first, then roll the flat surfaces.

Prime both sides and all edges. Allow the primer to dry fully according to the manufacturer’s instructions (usually 2-4 hours).

After the primer dries, lightly sand it with 220-grit sandpaper. This removes any raised wood fibers and creates an ultra-smooth base for your final paint. Wipe away all dust again before painting.

• Always sand with the grain of the wood.
• Work in a well-ventilated area and wear a dust mask when sanding.
• Apply primer and paint in thin, even coats.
• Sand lightly between primer and paint coats for the smoothest finish.
• For the best professional look, apply two coats of primer on bare wood doors.

Taking the time to clean, sand, and prime your interior doors properly makes a huge difference in the final result. Doors that are well prepped look smoother, last longer, and require fewer coats of paint.

Good prep work separates amateur paint jobs from professional-looking results. Follow these sanding and priming steps carefully, and your painted interior doors will look beautiful for many years.

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