This story covers preparing and painting doors.
Slab doors are the easiest doors to paint, but they require careful finishing to achieve a professional appearance. Remove the door if you can and set it on sawhorses. If you leave the door in place, remove all the hardware you can so it won't be in the way and won't interfere with straight roller or brush strokes. Mask off what you don't remove. Paint the door with a roller until you have an even coat on the entire surface.
Remove the door if possible or wedge it at the bottom to keep it steady and mask off the hardware (see "Painting a slab door"). Using a 2- or 3-inch sash brush, paint the edges of each panel. Then paint the face of the panel and remove excess paint in the corners before moving to the next panel.
After you've painted all the interior panels, roll the paint on the vertical center stiles (numbers 7, 8, and 9 in "Painting order"). You can paint slightly beyond the joints of these panels because the next sequence of strokes will cover these overlaps. Continue rolling the paint in the sequence shown on the previous page, finishing with the long stiles that run vertically the entire height of the door and the edge. Then level the paint with a 3- or 4-inch brush in the same order, always brushing with the grain. Let the door dry, then reinstall the hardware.