Lesson 3: Stenciling with Plaster
Special Effects
You may not want to pay the price for Venetian Plaster, or to get a plaster mold with ultra high relief. But even those can be faked inexpensively, as you will see here.
Venetian Plaster
You can create a reasonable facsimile of this very expensive technique by adding concrete sealer to your joint compound. Use about 7 tablespoons per cup of joint compound and mix well. This will create a pretty thin mix, but if you let it sit out for a while, it will begin to thicken again to the desired consistency.
Apply as usual and allow enough drying time. When it is thoroughly dry, sand it very carefully with fine grade sandpaper (320 grit) and follow with extra fine (400 or higher) if you can find it. Remember that your plaster is actually quite thin, so you want to use a light touch here. As you work, keep brushing away the resultant dust with a soft old brush, as those particles can scratch the surface you are trying to smooth.
Follow this with satin sheen paint or a mix of paint and glaze. Paint will go on to the surface silkily with very little absorption - the satin sheen will be quite apparent. If you use a mix of paint and glaze, the glaze will make the paint less opaque. With this slightly transparent effect, you can create a lot of interesting looks. You might be able to use sponges and brushes to create a faux marble effect on stenciled plaster columns, for instance, starting with an ivory color and then adding glazes in yellow ochre and a light touch of veining in burnt sienna. Twiddle the veins onto the wet ochre glaze and then take a soft brush and pull it diagonally across the "veins", first in one direction and then in its opposite. This will soften the "vein" and give it a realistic effect. Lightly sponge very thin glaze mixed with ivory over any areas that you think are too dark, and you will simply add a look of even more depth.
As with any time that you paint on stenciled plaster, be sure to allow at least 24 hours of drying time before you begin.
Special Effects - Painted Shadow
If you want your plaster design to really pop off the wall, you can stencil in a shadow before you apply the plaster. Place the stencil a fraction of an inch over to the right and down from where you want the relief to appear. Use pale purplish gray, or brown - or whatever color would be a logical color shadow for your finished piece. Allow that to dry. Now reposition the stencil, with adhesive, just ever so slightly above and to the left of the painted shadow and start to apply the plaster as usual. (Depending on your source of light, you may want to put the shadow to the left rather than the right, or above rather than below the plaster.)
When you remove the stencil, you will see that between the actual relief created by the plaster and the shadow your design takes on the illusion of much greater depth than it actually has.
