Cast stone is basically molded cement. There are different levels of finesse that differentiate high-quality work from regular home projects. Commercial producers use beautiful molds and computer-generated coloring to produce a very natural stone. However, if you are interested in trying your hand at making some cast stone, here are the basic instructions.
Things You'll Need
Prepare your mold by either spraying it with a nonstick kitchen spray for very small projects or by dusting it with a release powder. This ensures that when your stone has dried, you can remove it from the mold.
Mix your concrete according to the instructions on the package. Do not add too much water or it will not have any strength after it has dried. It is convenient to mix it in a wheelbarrow using a trowel or a hoe, depending on how much you are mixing. It should have the texture of pudding.
Add coloring. You can either color the whole batch of concrete or dust the surface with a powder colorant. If you are using the powder, dust it over the mold. Liquid colorant can simply be mixed into the wet concrete.
Push the wet concrete into the prepared mold. It should be sitting on a level surface in a place out of the direct sun. Tap it several times so that any air pockets are released. Cover it with a tarp or piece of plastic and let it cure for at least 24 hours.
Invert the mold onto a solid surface. Keep it clean and dry for about a week to let it thoroughly cure. This will ensure that the center of the cast stone is not damp.
Seal the concrete with an appropriate concrete sealer for whatever application you are using it.