Intricate concrete stamp adds style and texture to a vertical surface.
Stamping a concrete wall gives texture and depth to an otherwise plain vertical surface. The stamping process involves adding a layer of concrete overlay to an existing wall and then stamping the wet surface. You might want to enlist a few helpers to add and smooth the new concrete while another person concentrates on impressing the stamp. Once the patterned surface dries, you'll have a stylish wall that resembles natural stone, brick or other designs.
Prepare
Adding a new layer of concrete thick enough to stamp is not as simple as smoothing wet concrete on a wall. The overlay must form a strong bond with the existing concrete to reduce the possibility of cracks forming. Clean the wall with a scrub brush and a bucket of water to remove dirt and dust from an interior wall. If you're working outside, use a power washer if needed. Coat the wall with a bonding agent; agents come as powders or in liquid form. Follow the application instructions, which typically entail using a roller brush over the wall and a paint brush in corners.
Apply Overlay
A number of different concrete overlays are on the market. Look for a cement-based mix designed for vertical application. Wall overlays are about a third lighter than floor overlays for thick applications that won't sag. If your stamp impresses rock textures or other deep designs, you'll need to apply a layer at least 3 inches thick. Once the overlay is mixed, apply it with a trowel over a corner section of the wall large enough to press the stamp twice. Once applied, the overlay should be immediately smoothed with a straight edge.
Vertical Stamping
Impressing a concrete stamp into a wall requires precision. Before applying even pressure to the first stamp, see that the alignment is straight with the wall. Press the stamp no more than 15 minutes after the overlay is applied, and tap it with a mallet so the depth is consistent. Once the next section of overlay is spread and smoothed, align the stamp with the previously impressed pattern, and press it again. Continue stamping each section until the wall is finished. Go over light lines in corners by tracing the pattern deeper with the end of a trowel.
Maintenance
Give the stamped concrete one week to dry. Interior walls will dry slowly at room temperature. Spray water over an exterior wall throughout the week to prevent it from drying out too fast, weakening the bond. After a week, seal the wall with a low sheen, penetrating concrete sealant to fill the porous surface. Exterior sealant should be applied every two to three years, depending on the amount of harsh weather it's exposed to.
