Things You'll Need
Masonite doors are made from fiberglass to create an entrance way that's both attractive and durable. These doors look like real wood but will not rot or warp due to sun or moisture. While fiberglass doors can be expensive, homeowners can save money by buying unfinished doors. This allows the homeowner to stain the door themselves before it is installed. Masonite doors can be stained in almost any shade to complement many different types of home design and decor.
Remove the door from the opening, if needed. Use a center punch and a hammer to drive out the hinge pins, then lay the door across padded sawhorses. Spread newspaper or drop cloths beneath the door to protect the floor. Remove all locks and hardware from the door to avoid staining them along with the door. Cover any glass panels or other elements with painter's tape to protect them as you work.
Clean the door using acetone or mineral spirits. Apply these materials with a clean, dry cloth. Use another clean cloth to wipe the acetone away when your done. Make sure the room is well ventilated as you perform this task, and wear gloves to protect your hands.
Choose your stain. Masonite doors can be stained with any oil-based or gel stain. Avoid water-based products, as they tend to produce poor results. Test your stain on a small, out-of-sight area of the door before proceeding, as stains often look very different once they are applied.
Stir the stain thoroughly to ensure it is well blended. Use a foam brush to apply it to the door, working on one area at a time. For example, stain all panels, then trim, then side lites and so on. This will help maintain a visual separation between these areas. Rub away excess stain with a clean, dry cloth to maintain an even finish. Allow each area to dry for several hours before moving to the next section.
Allow the door to dry completely before turning it over and staining the other side. Don't forget to stain all four edges in addition to the two faces.
Repeat Steps 4 and 5 to apply several coats of stain until you achieve the desired finish. Do not sand the door between coats.
Wait until the door is dry, then apply a protective seal coat. Choose a UV-rated clear polyurethane sealer with either a gloss or matte finish depending on preference. Apply this sealer to the door using a bristle brush.
Reinstall the door once it has dried completely. Reinstall hardware as needed, then remove any protective tape you used to protect glass or other elements.