The wall texture you see by the light switch is pretty typical of new homes in the Katy suburb of Houston, and actually a little lighter than many builders use. These bumps would show under the new wallpaper, and also cause potential problems with adhesion at the seams, so I had to smooth the surface. To do that, I trowel on joint compound, which we just call “mud,” and which is something like plaster. The process is called “floating,” or “skim coating.”
It takes a while to dry, which can be sped up by using fans, and also by having the air conditioning or heat, plus the house fan, cranked up in the house to pull humidity from the air. Sometimes it needs overnight to dry completely. A heat gun is the final encouragement for stubborn spots. In the second photo, the mud has been applied and dried, and is waiting to be sanded.
The dust from sanding is like fine flour, and drifts onto everything, so it’s important to take steps to keep it off the homeowner’s furnishings – and out of the smoke detector!
I use an abrasive flexible sponge (not shown) to do the sanding by hand, and it goes pretty quickly. Once the sanding is done, the walls (and floor!) need to be vacuumed, and then the walls get wiped down with a damp sponge, to remove any remaining dust. This is a crucial step, because anything (wallpaper, paint, decals) applied over a dusty wall will delaminate and fall right off.
Once the walls are dry again, a primer is applied. When I have newly floated walls, which are porous, I like to prime with Gardz, a thin sealer that soaks into the surface and dries hard and intact. Gardz dries clear, which is why, in the fifth photo, the wall is smooth but you still see some of the paint from the wall underneath.
The last shot shows the pretty new wallpaper, free of bumps or distractions, and with a solid surface to cling to.
This wallpaper is called “Watercolor Peony” and is by Anthropologie.