Plaster ceiling designs are some of the most beautiful elements of classic Victorian home decor. By utilizing a few plastic or metal molds and some plaster of Paris, you can replicate some of these ceiling designs in your own home. Turn your traditional dining nook into an elegant dining room or your plain foyer into a grand entry hall in just a few simple steps.
Buy the plaster molds you would like to use. Molds come in many shapes and sizes and they can be found at craft stores or purchased from online retailers. The molds you select do not even need to be plaster molds, specifically -- candy molds also work well.
Create the design you would like to apply to your ceiling by arranging the plaster molds in different patterns. Be creative with circular medallions, flower shapes and decorative borders. Draw out a sketch of the finished product so you know how many casts you will need of each mold.
Mix your plaster of Paris by following the directions on the packaging. Fill a plastic tub or bucket with water and sprinkle the plaster of Paris over the surface of the water, sifting it through your fingers, until the entire surface is coated. Allow the powder to sit for 2 minutes then stir the mixture from the bottom up with a metal spoon.
Stir the plaster of Paris slowly and evenly until it begins to thicken. Once the plaster reaches the consistency of whole milk it is ready to use.
Coat the inside of your plaster molds with cooking oil to keep the plaster from sticking. Pour the plaster of Paris into the molds, filling them all the way to the top.
Set the molds aside to dry. This could take anywhere from 30 minutes to an hour, depending on the size of the mold. After 30 minutes, gently touch your finger to the plaster. If it feels warm or if your finger leaves an imprint, the plaster has not completely set.
Pop the plaster castings out of the molds by turning the molds upside down over your hand and gently press the casting out of the mold from the back and into your open hand. Set the plaster pieces in a warm, sunny area or near a radiator to dry for 24 hours.
Transfer your sketched design to the ceiling in pencil. Use a measuring tape or ruler and mark the exact position for each of the plaster molds.
Paint your plaster molds, if desired, with acrylic paint for bold colors or watercolor paint for subtle coloring. Allow the paint to set for several hours until it is dry to the touch. Apply a layer of clear matte acrylic sealer to protect the molds from moisture. Allow the sealant to dry overnight.
Attach the plaster castings to the ceiling by spreading a 1/4-inch layer of joint compound on the back of each piece with a putty knife. Press the molds into the ceiling in the desired location and hold each one in place for 30 to 60 seconds. Fill in any gaps around the mold with joint compound to create a cohesive look. Wipe away any excess joint compound with a damp sponge.