Trowel On

As long as you plan ahead and gather the right materials, coating your walls with clay plaster will be an easy and satisfying weekend project. Here are the tools and techniques you’ll need:


  • 150-grit wet/dry sandpaper
  • fiberglass joint tape
  • all-purpose joint compound
  • putty knife
  • drop cloth
  • painter’s tape
  • rigid steel rectangular plaster trowel
  • plaster hawk
  • roller brush
  • small paintbrush
  • paint tray, stir stick
  • particulate face mask
  • heavy-duty ½-inch drill
  • attachable mixing paddle
  • 5-gallon bucket
  • Chapin Multi-Purpose Sprayer
  • tile sponge

Master the Tools

The traditional plastering tools may sound intimidating, but they just take practice to master. Hold about 1 cup of plaster on the hawk and scoop half of it onto the trowel with your dominant plastering hand.

Know Your Site

Each work site has its own preparation and application requirements, depending on the existing wall surface. These steps are for plastering over a painted wall. But before you get started, consider whether you have lead paint. If your room hasn’t been painted since before 1978, it just might. Adams says a good gauge is to check whether the paint is flaking; if it is, it probably contains lead. In that case, have professionals like Global Pacific Environmental (503-223-4401) test and remove it.

If your wall is covered in glossy paint, sand it lightly with 150-grit sandpaper to give it tooth. For all paint finishes, cover any cracks from ¼ inch to 1 inch wide with fiberglass joint tape. Next, seal these cracks and any small depressions with joint compound, using a putty knife to apply the compound so that it’s flush with the wall. Let it dry completely.

Before you begin priming and plastering, protect the floors and adjacent furniture with a drop cloth, set up a fan for ventilation, clean all dirt or grease off the wall, and apply painter’s tape around the trim and ceiling seams to protect them.

Prime Time

Traditional earthen plasters required a layer of chicken wire or burlap underneath to create a textured surface to which the plaster would bind. To most modern plasterers, this is a recipe for an unrefined, caveman effect. Fortunately, there’s an alternative: Ecohaus (819 SE Taylor St, carries American Clay’s Sanded Primer Elite, which creates an ideal surface for the plaster to bind to. It goes on like a coat of thin paint and should be applied with the shortest-haired roller brush you can find. Be sure to stir the primer well, until it has the consistency of paint and the sand is mixed throughout. First use a smaller brush for cutting in at the corners and along the trim, then pour the primer into a roller pan and use the roller brush to apply an even coat to the wall. Allow 3 hours for it to dry completely.