How to Make Plaster and Cement Items with Molds
To get started you will need a mold, plaster of paris or cement, vegetable oil, large bucket and gloves. I have used simple round 9″ cake pans as a mold for stepping stones or you can purchase a professional mold. These may be hard to find locally, but are readily available online. You can easily find them by searching with terms such as stepping stone mold, cement mold or plaster mold. To decide on whether to use plaster or cement you must first consider what kind of an item you are planning to make and if it will be located outdoors. As a general rule, use cement for outdoor items and plaster for indoor items. Plaster items don’t seem to hold up to well outside if you get a lot of extreme weather. I like using plaster a little more because it will dry a lot faster and you can usually obtain more detail than with cement. The plaster and cement can be found at any hardware store. I wouldn’t recommend buying the plaster at a craft store because it is usually 10 times more expensive than the hardware store. You should be able to buy a 25 lb. bag for about $10-$15.
Now that you have everything together you can get started creating items. First, you want to take the mold and grease it very lightly with the vegetable oil and put it aside. Now put on your gloves and add plaster into the bucket outside. Usually the correct amount of dry plaster you need to pour into bucket will be about 2x the size of the mold. Then, just start adding small amounts of water and mixing it at the same time. When it is ready to pour into the mold, it will have the same consistency as pancake batter. At that point, start pouring it into mold slowly. It is important to keep shaking your mold gently as you pour in the plaster to avoid air pockets. At that point, you just want to let your mold sit for 30 minutes to dry. With cement you would follow the same procedure, except cement takes 24 hours to dry. Do not let your molds dry in direct sunlight or they will crack. Your item will be ready to remove by turning it upside-down and lightly tapping on the sides of the mold. You can leave finished piece just as it is or paint it at that point. Finally just add a light coat of concrete sealant and your creation will be ready for years of enjoyment.