How to Use Plaster Arch Formers

Put on your safety goggles and face mask. Prepare the opening on the wall where you are going to install the arch by removing any paint, wallpaper and plaster down to the brick with an electric sander.

Position the arch former segment against the opening in the wall, so that it is snug and extending 1/2-inch up onto the wall on all sides. Nail the arch segments into the wall with the provided masonry nails. Position the nails 1 inch apart on the former.

Cut a 1-inch piece of galvanized wire tie with tin snips. Insert the wire at the ends of the arch pieces, right against the end of the wall with half of it sticking out. Press the arch against the wire with a pair of pliers. The wire will be a support link for the sections.

Place the connecting arch drywall bead between the right and left sides of the arch to join the pieces together. If your wall is less than 6 inches thick, use the provided Soffit and self-tapping screws to make the arch thicker. Do this by overlapping the provided Soffit pieces against the wall and securing them into it with the self-tapping screws, then place the arch segments over the Soffit and nail into the wall.

Add the other half of the arch formers to the other side of the opening in the wall in the same manner.

Cut another 1-inch section of galvanized wire tie. Insert the tie in between the two arch formers where they intersect, halfway up from the bottom of the formers. Twist the wire tie to secure it in place, then bend the ends down into an opening in the lathe with a pair of pliers. Do the same for the other corner of the arch.

Nail standard angle bead onto the vertical corners that lead up to the arch with galvanized masonry nails spaced 1 inch apart.

Install the PVC arch nosing. Place the end of the arch nosing at the bottom of the joint where the arch and the vertical corner angle bead meet. Run the arch nosing up along the arch, and press the ends into the arch forms with your thumb to snap them into place. Trim excess nosing with tin snips.

Apply a 1/4-inch thick coat of plaster to the arch former. Wait overnight for the plaster to dry into a rough hard surface.

Use a plaster float to add a 1/8-inch layer of the finishing plaster over the hardened metal lathing plaster and smooth it to a level even surface. Wait 48 hours for the plaster to dry before sanding and painting it.