Plaster of Paris is used in a variety of applications that range from the medical field to several disciplines of art. It possesses a lot of utility, especially if used with the help of molds in the field of arts and crafts. It is basically a form of gypsum that was found in Paris, and was frequently put to use by the reputed artisans of Paris. If used properly, it is like an ideal material that can be used right from making molds and casts to using it in the form of building material. This form is basically found in a powdery form, and is then mixed with water in order give it mountable and cast-able semisolid form.
Methods to Use it in Molds
Here are some simple instructions on how to use plaster of Paris molds to obtain best results, because the setting of the plaster in the mold largely depends upon the method of mixing of the plaster and water.
If you are planning on using the molding and casting process, you need to first consider the mixing, apart from the molds. Plaster of Paris is usually available in the form of a fine powder. It is always advisable to follow the instructions that are given by the manufacturer while preparing the mixture. It is basically made up of 3 different compounds, namely, calcium sulfate hemihydrates, calcium carbonate, and crystalline silica, which vary in minute quantities from manufacturer to manufacturer. Hence, while making objects with the help of molds, it is safe to follow the recommended quantities in order to have consistency in the plaster once it is mixed, and also to stimulate drying and molding. I strongly recommend that you use a mixing bucket in order to have an even blend. If you are allergic to the plaster, use a pair of rubber gloves. In fact, don't hesitate, use the gloves. While mixing the plaster, take the recommended quantity in the bucket, and then add the powder in the bucket of water.
In order to get hang of the molding process, first use simple shapes and combinations such as, small candy molds. Molds of different types are also available in many hardware stores. I would recommend that if you are using the molding process for the first time, then you use standard plastic molds. First, pour the mixture of the powder and water, that now resembles sludge, into the mold. Be sure that you pour down the mixture very slowly and gradually so that no gap is left in the cast. Also, shake the mold well, when the mixture is still in its semisolid viscous state.
While making different objects, there are a few simple things that you can try out in the whole process. For example, pour the mixture down into a small plastic bowl. Do not fill the whole bowl till the brim. Then, place a small coin (insert the face) in the mixture and even it out. Remove the coin, and then the cast after the mixture has dried. You will get a beautiful imprint of the coin in the plaster mold.
Removal of the molded object from the mold is the most difficult task to perform. The plaster can take anywhere between a few minutes to an hour to dry up. The basic drying period of the object is determined by its size. The key is to feel the moisture with your finger. When the plaster is still a bit moist, remove the object from the mold as delicately as possible.
For additional information and directions, refer to the manufacturers instructions to make simple objects, like artificial coins, paperweights, artificial candy, or small statues.