How to Make Ledgestone Concrete Molds
- 1). Arrange the ledgestones in a pattern on a flat surface. The stones should be placed to create a single stone section made up of the individual stones of three to five feet in length, with a width of no more than two feet. Creating a mold much larger will make the veneer too heavy to work with. The top two inches of the ledgestones from the top surface of the stones downward will be reproduced by the mold, creating two-inch thick stones that can be placed in mortar on a surface, to replicate the placement of full-sized stone. Place the stones so that they create a repeatable pattern that blends seamlessly across the individually cast sections. To do so, arrange the pattern so that the ends of the stones are staggered such as the placement of bricks on a brick wall. The right end of the pattern should fit snugly into the left end of the pattern like a puzzle piece, with the top of the pattern fitting in the bottom as well. This will allow the veneer to be placed continuously in a line using multiple segments.
- 2). Build a wood frame to hold the mold during its creation. The wood frame should be the size of your stone arrangement plus two inches to allow for extra space on the mold for handling. Make the frame high enough to rise above the height of the stones by one and one-quarter inches. Secure the edges of the frame by nailing at the corners and then seal the seams of the frame using duct tape to prevent the mold making material from seeping out. Create the mold in an easily handled size, between three to six feet in length. Cover large surfaces by casting multiple sets of veneer and then joining them together on the application surface.
- 3). Using a paintbrush, brush the surface of each stone with a stone sealant. Allow the sealant to dry for two hours and then glue the stones to each other in the set pattern using epoxy glue. Wait a further two hours for the glue to dry.
- 4). Place a bed of clay into the bottom of your wooden frame one inch thick. Place the ledgestones into the bed of clay, centered in the frame. Build up the clay surrounding the stones until only the upper two inches of the stones and their surfaces remain exposed. When finished the sides of the frame should be a quarter inch higher than the stones themselves. This is so that the mold material will cover the stones with additional material to develop a mold backing one-quarter inch thick.
- 5). Spray the ledgestones, clay and sides of the wooden frame with the mold release agent to prevent the mold from sticking.
- 6). Mix the silicone rubber mold mix following the directions provided by the manufacturer of the mix. Pour the rubber over the stones, covering the stones and the clay bed up to the level of the frame one-quarter inch above the stones.
- 7). Tap the side of the frame to force air bubbles to rise to the top of the rubber mold mix. Continue tapping for several minutes until the air bubbles stop. Removing the air bubbles gives you a better reproduction of the surface of the stones.
- 8). Wait about 12 hours for the rubber to cure, creating a solid mold. Remove the rubber by peeling it away from the ledgestones and frame. The mold created should replicate the top two inches of the ledgestones.
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