Plaster molds help increase the output of your ceramics studio.
Ceramicists know that clay molds made from CastRite plaster of Paris are among the very best in the world. CastRite's gypsum-based formula produces molds that are durable, detailed and will not chip or chalk. But the limited selection and hefty price tags of commercial CastRite molds can be prohibitive. Hobbyists and professionals alike can easily make their own basic CastRite molds.
Instructions
1. Keep your original simple.
Select an item for your mold's "original." Avoid objects with intricate details or long, delicate appendages.
2. Measure the largest points of length, width and height of the original. Multiply each measurement by 1.25 to get the dimensions for the mold box. For example, an object that measures 2-by-4-by-6 inches would require a box 2.5-by-5-by-7.5 inches in size.
3. Construct two bottomless boxes using the measurements calculated in step 2, using plywood and wood screws. Use the smallest dimension for the height. Cut a piece of heavy corrugated cardboard slightly larger than the boxes.
4. Center one of the plywood boxes on the cardboard, and secure it by smearing clay along the edges where the two meet. Also smear clay along the inside edges of the box to create a watertight seal. Use a soft-bristle paintbrush to coat the bottom and inside walls of the mold box with a thin layer of petroleum jelly.
5. Clean the object you wish to mold with water and a mild soap. Fill any openings in the object with clay. Apply a thin coat of petroleum jelly to the entire item. CastRite plaster picks up many fine details that other plasters do not, so be careful not to over-apply the petroleum jelly.
6. Mix plaster until it is lump-free.
Mix seven parts CastRite plaster to eight parts water in a plastic tub. Stir until well-blended and smooth. During setting, the chemical reaction that hardens CastRite produces enough heat to burn skin. Once the plaster is mixed, wear gloves and avoid direct skin contact.
7. Fill the mold box with the plaster.
8. Submerge half of the original object into the plaster. Make sure that it does not touch the box's walls. If the object floats, wait one minute and try to submerge it again. Do this until it stays in place.
9. Allow the plaster to cure for approximately 10 minutes. You should be able to leave a thumbprint in it with minimal effort.
10. Hollow out a channel from the top or foot of the original object to the nearest wall of the mold box. Fill this depression with a cylinder of clay to create the mold's plug. Make a circular indentation in the plaster of each corner by holding a large coin between your thumb and forefinger and twisting it 360 degrees. Allow the mold to cure for another one to two hours.
11. Cover the rim of the mold box with a thick bead of clay. Place the second mold box on top of the first, covering the other half of the "original." Smear the clay bead to create a watertight seal. Coat the exposed plaster and the inside walls of the second box with petroleum jelly.
12. Mix the plaster as you did in step 6. Pour it into the mold and allow to dry for another one to two hours.
13. Dismantle the top mold box by taking out the wood screws when the plaster is completely hardened. Gently slip the plaster block off the bottom half of the mold. Remove the clay from the plug and work the original object out of the mold.
14. Remove the bottom mold box and clean off any remaining clay. Let your new CastRite plaster of Paris mold cure overnight to maximize its durability.
Related posts
With a two-part plaster mold, you can create a negative 3-D cast, or a hollow mold, of almost any object and recast that object in a variety of materials. Plaster molds work particularly well for...
You can easily make a nontoxic plaster mold in a home workshop or studio.Plaster is an excellent material for sculpture, crafting and mold-making. It is easy to work with, it dries quickly and, us...
Molds for many plaster crafts can be made from molding clay or carved into pieces of wood. Clay is best used when only a portion of an object is going to be replicated with plaster, simply by pres...
Creating identical copies of existing objects or parts is a professional-level task, but can also be done at home by any beginner. This process is called casting, and consists of pouring a materia...
Gather Materials and Prepare PartitionTo create a simple plaster mold, you will need the object to be molded; clay; two disposable containers; Vaseline, mold release or orange shellac; plaster; wa...
