Tape the baseboards and around windows and doors using painter's tape, and place drop cloths on the floors.
Scrape any bumps or irregular surfaces on the walls flat, and apply crack filler where needed to create a smooth surface.
Pour the primer into a roller tray and prime the walls using a 3/8 inch roller, then allow the walls to dry according to the manufacturer's directions.
Pour the Venetian plaster into a roller pan and use a 3/8 inch roller to roll the plaster onto the wall in a 3 foot by 3 foot section.
Use a steel spatula to move the applied plaster in different directions in an overlapping pattern. Try to use a random motion to avoid leaving an even pattern, especially along the edges.
Apply the Venetian plaster product with the roller to the next 3 foot square section and use the steel scraper to move the product in an overlapping pattern next to the previous section.
Repeat this application until you cover the entire surface. Let this first coat dry one to four hours until matte and lighter in color.
Apply a second coat using the steel spatula with a small amount of Venetian plaster on the blade. Start at the top of the wall and apply the plaster thinly in a random pattern, moving back and forth and side to side.
Cover the surface completely using the steel scraper and plaster, then allow to dry for another one to four hours.
Smooth the surface with the steel spatula for a polishing effect, then polish the surface further with a nylon kitchen scrubber, moving in a back and forth motion.
Buff the completed surface using fine steel wool in a circular motion to polish the surface to a high-gloss finish if desired.