Lay down the drop cloth to avoid drips on your floor from the faux-texturing material. Put on the gloves to protect your hands.
Apply two coats of the tinted primer with the paintbrush. Pick a primer color that closely matches that of the sand wash. Brush on the primer by starting at the top corner of the wall, applying a 2-foot strip across the ceiling edge and down the corner of the walls.
Fill the 3/4-inch nap roller with sand wash and apply the wash to a series of sections on the wall, each covering an area 2 feet by 2 feet. Create a column look down the wall by covering more sections of the same size. Each section should slightly overlap and have a wet edge.
Apply a thin coat of sand wash over the wall to cover the entire column until the wall is done; allow four hours to dry.
Apply a second coat of sand wash and allow 24 hours for it to dry.
Apply a top coat of clear, water-based polyurethane, particularly if the area being textured is in a high-traffic or high-moisture location. Allow seven days to dry.
Round the edges of the flexible steel trowel, using the sandpaper.
Put the Venetian plaster in the trowel, test the color on a smaller surface, then spread it on the wall at a 15- to 30-degree angle. Use random long strokes, followed by short ones. Use a thin layer in some places so the original surface can be seen. Allow four hours to dry.
Add a second coat by spreading a thin layer of plaster at a 60- to 90-degree angle. The strokes should be long, short and overlapping. Wait 24 hours before applying a burnishing or top coat to the faux texture.
Hold the trowel at an angle to apply a thin layer of top coat. Venetian plaster should have a satin sheen when dry. Don't apply a top coat and a burnishing finish to the same wall.