
photo credit: Todd Baker << technowannabe
I spent the weekend painting all of my newly installed 6-panel, solid core, molded, interior doors. What a job! I followed the following instructions from Masonite (the manufacturer of my doors) and got really good results with almost no drips. I’m going to post them here for reference.
How to paint a molded pre-primed interior door
1) MATERIALS REQUIRED:
Paint - A high quality semi-gloss enamel. Always follow the paint manufacturer’s instructions for the paint preparation and application.
• 3”-4” Black China or Synthetic Bristle Brush
• 1” Black China or Synthetic Bristle Brush
Use a black china bristle brush for oil-based paint and a synthetic bristle brush for latex paint.
2) Remove all hardware and fill any nail holes and blemishes with wood filler.
3) Sanding of pre-primed doors prior to painting is not recommended. Primer is not necessary on pre-primed doors.
4) Wipe down with a tack cloth to ensure a dust free finish.
5) Paint door in the following order: start with the door panels (1), then the center stile (2), then paint the horizontal rails (3), then the vertical door stiles (4).
Remove any excess paint from the corners of the panels or lite grilles by feathering with a dry 1” brush.

6) When painting stiles and rails, use long strokes to prevent paint from pooling where the horizontal rails and the vertical stiles meet. Paint the four
edges last (top, bottom, left and right).
7) Allow the paint to dry thoroughly before applying a second coat.
Consult the paint manufacturer’s directions for drying times.
8 ) Paint (all 6 sides) to completely seal and to restrict moisture absorption.
9) After finishing is completed, reinstall all hardware.
(Source - Summarized from Masonite’s “Painting Interior Doors Guide“)