Mix the stucco. Fill a cement mixer with 1 cubic foot of hydraulic or masonry cement mixed with hydrated lime; 3 cubic feet of plaster sand; and 5 gallons of fresh water. Mix for 60 seconds until the stucco resembles a thick paste. The mix is enough for "1,440 square feet at one half inch thick per hour," according to Mortar Sprayer.
Stop the mixer. Shovel the stucco into a wheel barrel. Wheel the barrel over to the place where your stucco work will begin. Keep a wheel barrel filled with stucco within at least 6 feet at all times during the process.
Turn on the gasoline engine connected to the sprayer.
Dip the stucco hopper directly into the wheel barrel mix. Fill the hopper with stucco and remove it. Hold the stucco sprayer perpendicular to the wall. Position the nozzle 12 inches away from the wall.
Pull the sprayer trigger. Hold the trigger for one second and release. Move the nozzle up and down in a vertical motion or back and forth in a horizontal motion as you spray. Spray at one- to two-second intervals. Refill the sprayer hopper every 10 or 15 seconds.
Spray stucco until it's 1/2 inch thick on the wall. Turn off the sprayer engine. Duck the hopper into a fresh bucket of water to rinse it off. Even out the stucco -- if you want -- with a large metal paint scraper. Place the scraper blade flush against the wall. Move the blade in arcing motions all around the surface to even the coating.