Plastering scrim is a technique that involves the installation of parallel lines across the backing. You can think of it like bondage tape. This allows for excellent control over the wall surface and definition in areas where the painting will be required. There are many types of scrim installation, but this article will deal with paper-backed mesh scrims. Most importantly, these scrims should not be confused with tension fabric-backed scrims or plastic mesh scrims often used for rendering or screeding mediums for concrete formwork, etc.
The primary sequence when installing scrim is to start at one corner, place your first strip edge up against the corner bead (where timber stud walls stop), making sure that it is tight all the way along. Go to your next corner and place a strip edge up against the first strip. The two strips should butt tightly together without any ’ gaps between them. If there are gaps, either you have not installed the previous strip correctly, or this double-sided tape is too weak for your needs.
After you have completed both corners, install another piece running from top to bottom on the wall; however, do not go back under the corner bead as there will be no more connection points at that point. Now cut across each side of the first half, so it creates small triangles. These triangles become hooks that help hang other pieces in place. Continue making this pattern until you reach the other side of the wall, if necessary, overlapping one of the triangles over the corner strip.
When you near your next corner, leave a small section of the last piece sticking up off the wall about 45mm. This is to allow you to hang another piece on it when you get to that point. Do this at all significant corners in your work area and then finish with extra pieces cut into specific shapes around outlets etc.
If you are cutting across large areas with no corners, try to install continuous strips top-to-bottom or left-to-right so that any small breaks in the pattern help break up large areas.
For larger open areas which require shaping or definition (such as drop-down ceilings for lighting), utilize laps’ in your installation pattern so they create triangles that can be folded over the top of the drop down.
As you install your scrim, there is a fine line between tight and sticky; if it’s too close, it becomes difficult to cut or fold into the right spot without ripping off strips, however too loose, and you are creating gaps in your finish which will require filling. If possible, try using two different thicknesses of tape on either end of your run for this reason.
Scrim plastering allows for excellent control when finishing off with paint lines or texture. Not only does it make masking easier, but there are often textures molded into the commercial paper-backed mesh, which allow the paint to grip far better than straight wall surfaces – hence crim.’
Several kinds of commercial scrims are available; some even have vinyl backing, making them easy to put up and store. The most common paper-backed mesh is the asi-score’ brand. These come in rolls which you can snap off at regular intervals giving you quick dispensing options.