MDF, or medium density fiberboard, inside doors are an inexpensive alternative to genuine wood. But with the lower cost comes lower quality, so you will need to put more into the prep work to have the door ready for paint. The porous material of the door should be coated using an oil-based sealing primer before you paint. Use a paint sprayer to use a top notch latex paint to get professional results.
Lay dropcloths on the floor. Place two sawhorses up in a ventilated work area.
Twist a shim under the edge of the door for support. Remove the screws from the door hinges using a drill or a screwdriver. Remove the door from the frame and take it to the job area.
Lay the door round the sawhorses, every finish balanced on one sawhorse, to evenly distribute the weight. Remove the doorknob and the hinges, using a drill or a screwdriver.
Put on a dust mask and then sand the entire door, such as the edges, using a fine-grit sanding pad. Remove the sanding dust with a vacuumcleaner. Vacuum the corners of raised panel doors completely to remove residual dust.
Clean out the door of dirt and greasy residue using a degreasing cleaner and a clean cloth.
Put on a respirator and protective eye wear. Fill a paint sprayer with sealing primer. Hold the spray gun roughly 1 foot from the door and use a light coat of primer, using smooth, sweeping moves, making sure to spray the edges. Moisture can enter unsealed edges, causing the door to swell. Permit the primer to dry thoroughly. Apply another coat of primer and let it dry.
Fill nail holes and dents in the door with vinyl spackling using a putty knife. Wipe excess spackling using a clean, moist cloth.
Clean out the paint sprayer and hose using sterile water in the event that you used water-based primer or paint thinner to get oil-based primer.
Fill out the paint sprayer using paint. Hold the spray gun roughly 1 foot from the door to use a light coat of paint. Spray the door, such as the edges, with paint using smooth, side-to-side, sweeping motions. Maintain a consistent distance as you spray to ensure uniform paint coverage. Permit the paint to dry for the total amount of time recommended by the manufacturer.
Apply another coat of paint to the door and let it dry for 24 hours. Turn the door over and repeat the process on the opposite side. Permit the door to dry for 24 hours before replacing the hardware.