Stepping stones are used for decorations in lawns and gardens. They are made with concrete, sandstone or red clay. Stepping stones can have smooth, flat surfaces, be decorated with imprints of leaves and hands, or have pictures carved into their surfaces. Making rubber latex moulds out of your favourite stepping stones is moderately easy. Once the latex mould is finished, you can pour a mix of concrete and water into it and make as many stepping stones as you like.
Apply Super Seal with a paint brush onto the stepping stone you are going to use for your stepping stone mould. Cover the entire surface of the stone, including the top, back and all of the sides. Use the paint brush to push the sealant into any crevasses or decorative pattern indentations that are on the stepping stone's surface. Super Seal creates a watertight seal that will protect your original stepping stone while you make a mould out of it, preventing the stone's porous surface from absorbing the liquid latex, which can ruin it.
Wait three hours for the sealant to dry. Paint another coat of Super Seal onto the stepping stone. Wait another three hours for the sealant to dry.
Spray an even coat of the universal mould release onto the stone, covering it in small, vertical-striped sections. Universal mould release makes the set or cured latex pull easily off of the plastic bucket and the stepping stone, much like spray oil on a baking tray works when you are making cookies. Overlap each spray pass by 1-inch to ensure that the entire stone is covered with the mould release. Set the stepping stone aside and allow it to dry for an hour at room temperature. Spray the sides and bottom of the large plastic storage bucket with the universal mould release in the same manner.
Run a bead of silicone caulk along the bottom side edges of the stepping stone. Set the stepping stone, caulk side down, into the centre of the large plastic storage bucket. The silicone caulk will keep the stepping stone from moving while the liquid latex is curing. Spray the sides of the bucket with the universal mould release. Wait for the universal mould release to dry.
Mix one part of the cement latex rubber mould mix concentrate to eight parts water in a bucket with a wooden paint stick to make the liquid latex. Make enough of the liquid latex rubber mix to cover the stepping stone 1-inch above its top surface, about one gallon. If you are worried about making too much liquid latex, you can mix it in small batches and pour it over the stepping stone in the plastic storage bucket as you go until you have covered the stepping stone with a 1-inch-thick layer of the liquid latex.
Pour the liquid rubber mixture over the stepping stone, starting at the lowest point in the bucket, at a slow, constant rate. Keep pouring so the liquid rubber rises up and covers the model by 1-inch. This displaces any air and minimises air bubble formation in the mould. Place the mould in a 77 degree Fahrenheit room and allow to set or cure overnight.
Pry the cured rubber out of the plastic bucket to reveal a negative impression of the stepping stone in the mould.
Purchase a plastic storage bucket that is two times the size of the stepping stone you want to make a mould out of. You can get wooden paint sticks for free at any store that sells paint.
Work in a well-ventilated room. Wear protective clothing.