The key to using Venetian plaster is in the technique used to apply thin plaster layers and to burnish these layers to create an impression of depth and luster. This technique requires not only a special application of plaster but also special application tools. Check out the information below to learn more about this technique and the tools and materials necessary to perform it.
Apply Brick Mortar
To successfully apply Venetian plaster to a brick surface you will first need to fill in all joints and depressions in the brick surface. Mix your dry mortar with water and apply this mix to the brick surface, being careful to leave a flat, smooth surface. Allow the mortar to dry, then examine the surface for ridges, dents, or irregularities on the surface. Fill in dents and depressions with a new coat of mortar, and smooth the surface. Where you find ridges or high spots, sand these down until the surface is smooth. Clean off all dust and debris, using a soft brush or damp sponge.
Use a Japan scraper to apply the plaster. This tool will help you avoid ridges in the plaster as you apply it. Begin applying the plaster at one of your wall's top corners, applying only a small amount until you have worked it and are ready to apply the next patch. Apply the plaster in thin layers, as you would apply drywall joint compound. First, apply it in one direction, then a stroke in a different direction, moving and stroking the plaster until you get a flat, smooth surface. Then proceed to apply and work your next patch. Be sure you don't leave lines or thick layers. Work quickly with each patch. This plaster is applied in such thin layers that it will dry quickly when applied.
Sand the Plaster
When your first coat has been applied to the wall surface, allow it to dry. Then, sand with a sanding block to smooth away any bumps, peaks, or lines. The surface must be smooth after each application and sanding. Ultimately, it should be as polished looking like marble. When finished, apply a second coat, as thin and smooth as was the first coat. When it's dry, sand this second coat. Then do a third coat, dry and sand.
Burnish the Plaster
With a stainless steel trowel that has rounded edges—no corners that can leave marks and lines—press its surface against the plaster surface and work it in a circular motion. Pressure against the trowel as you move it across the surface of the plaster gives the plaster a marble-smooth finish, so put as much pressure as possible on the trowel.
Apply the Sealer
Use your trowel, now, to burnish the sealer onto the plaster surface. When the surface is dry from applying the sealer, burnish one last time to fill pores and give the wall a shiny, glossy appearance.