According to San Francisco Victoriana, moldings were used to frame the ceilings in structures of ancient Greece that were "built in the service of religion." While crown molding, as such, is a more modern invention, it has its roots in the classical world. When you are using crown molding in a room that has difficult and bull-nosed corners, it may be necessary to fashion crown molding out of plaster when you are on the site. The result will be a seamless transition from wood to plaster to wood again that will be imperceptible from the ground.
Things You'll Need
- Crown molding
- Drill and 3/8-inch bit
- Two 3/8-inch dowels
- Wood glue
- Finish nailer and brad nails
- Bonding primer and brush
- Rosin paper
- Expanded metal lathe
- Wire cutter
- Pencil and paper
- Jig saw
- Screws and screw gun
- Putty knife
- Settling compound (slow drying)
- Profile knife
- Joint compound
Install the crown molding all around the room except at the interior corner where you wish to make the plaster crown molding. Leave a gap that creates a 90 degree angle.
Drill two holes in the molding on either side of the gap. Put wood glue into the holes and insert two 3/8-inch dowels. Secure them with brad nails. Paint the interior of the gap with bonding primer.
Crumple rosin paper and stuff it behind the dowels. Cut two pieces of expanded metal length to size and staple it to the dowels and the ceiling to create a rounded shape. You will have a cone shape in the gap.
Pack mud on the wire mesh with a putty knife.
Hold paper on the ceiling and trace the curve that you created with the expanded metal lathe. Cut out the shape and trace around it onto a piece of plywood. This will be the pattern for the plaster crown molding. Cut the plywood and secure it to the ceiling with screws.
Apply slow drying settling compound on the mud until it is built up. Make sure you sand each coat and vacuum it so as to remove any dust that could keep the plaster from sticking. Sculpt the compound with a profile knife to match the profile of the crown molding.
Fill in any holes or divots with a putty knife. Apply joint compound on the area for the final coat. Paint the crown molding when dry.
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