Basics

• Mix 2 parts plaster of Paris to 1 part water. Verify the mixing ratios on the package as they may vary among brands. Add the plaster slowly while stirring so that it mixes in thoroughly. The mixture shouldn't be watery but still thin enough to pour slowly off a spoon. The thinner the mixture the longer it takes to dry.
  
  Paint finished plaster with acrylic paints. Plaster of Paris is porous so avoid water-based paints if you want bold colors. Seal finished pieces with a clear gloss or matte paint if desired.
  
  Wipe out mixing bowls and spoons immediately after use. Avoid putting unused plaster down the sink as it may clog drains as it hardens.
  
  

Molds

• Make molded pieces by pressing an object into the plaster of Paris. A mold is the imprint that is left behind. Use plaster molds as a decorative element or to make a mold for casting another substance such as clay.
  
  Pour the plaster into a form. Pie plates are commonly used for children's projects, or make a form by gluing cardboard strips together---such as squares for tile forms---and set on a cookie sheet lined with foil.
  
  Allow the plaster to set up for 10 minutes in the form after pouring. Press an object into the plaster then carefully remove. The mold of the object will remain. Examples are hand prints, shells or rocks. Allow the cast to dry overnight then carefully peel off the form.
  
  

Casts

• Cast are the opposite of molds---they are a three-dimensional representation of an object. A mold is necessary to make a cast. Use any pliable substance as a mold. Coat first in a thin coating of petroleum jelly or nonstick cooking spray to aid removal.
  
  Silicone and rubber ice cube trays with decorative shapes make attractive molds for cast plaster. Plastic soap and candy molds are other options. Make your own mold with clay. Make a smooth block of clay and either push objects into it or carve a shape into it. Pull it from the plaster once cured and save the clay for another project.
  
  Mix the plaster and pour into the mold. Be careful not to overfill. Remove from the mold after the plaster has cured 24 hours. Use fine grit sandpaper to file off any rough areas.