Fake boulders are used in a lot of ways. You can hide outside speakers in boulders, line your driveway safely with them, and they are used around ponds and for waterfalls. No landscape is complete without a few rocks or boulders. There are several ways to make boulders. You can use papier-mache, fiberglass or cement. One of the most durable ways is using a cement mix called hypertufa. Hypertufa is also very light and can be easy to carve.
Instructions
1. Determine the size of the boulder you want to make. Make a boulder form from hardware cloth or chicken wire. Fill it with plastic bags or Styrofoam.
2. Cover the form with duct or packing tape. Make sure the whole form is covered so the cement mix will adhere to it properly.
3. Wearing a dust mask, mix the Portland cement, peat moss, and perlite. If you're using dry colorant in the cement, add it to the dry ingredients before mixing in water. Add a little acrylic fortifying additive (for strength) to the water and mix well. Combine all of the ingredients, adding the water mixture a little at a time to create the hypertufa. Its consistency should be like oatmeal. It shouldn't be runny.
4. Apply the mixture to the form. Build it up by patting the mixture on the form with your hands, until it's 1-inch thick and the hardware cloth or chicken wire is completely covered. Use latex or vinyl gloves when handling the cement mixture.
5. Put plastic wrap on the boulder so it dries slowly. This may take up to several weeks to cure, but not less than five to seven days.
