Search Metal Clay Articles:
Using Cork Clay to Make Hollow Objects
by Mary Ellin D'Agostino
You can make hollow beads and sculptures using PMC+ Paste and Cork Clay. The process is similar to making a silver leaf, only instead of only coating one side of your mold, you are coating the entire surface.
Cork Clay is a non toxic modeling product that is an excellent core for making silver clay beads, sculptures and other hollow forms. Wash hands after using.
Keep all unused portions wrapped tightly in plastic. Once the Cork clay has dried, it cannot be re-moistened. Store at room temperature. Dark spots in the clay will not affect its performance.
Shape the damp cork clay and allow it to dry completely-overnight or in a 200 oven for several hours. It is best to dry the cork clay slowly. If there is moisture in the clay, the cork may expand during firing causing your piece to become cracked or to burst open. Beads can be many shapes and sizes; sculptures can be amphora (pot) shapes, birdhouses, teapots, cups, boats, baseball bats, animals, human figures, or just about anything you can imagine.
Before it dries, fine silver wire handles or findings can be inserted into the cork to hold them securely while applying the silver clay paste. Do not use other silver wire with unfired PMC+ because it will probably be sterling silver (92.5% silver and 7.5% copper). The copper in sterling silver burns at the temperatures PMC+ is fired at; it will turn black, be too weak for hanging, and may damage your piece.
It is also useful to insert a skewer or toothpick into the cork, to hold while applying the silver clay paste. Skewers are also useful for keeping the holes in beads open.
After it is dry, the cork clay may be finished further by sanding, drilling, or filing to the desired shape and smoothness.
Coat the cork form with 10 or 12 thick layers of PMC+ Paste. If the silver paste is too thin, the piece will crack or break. Remember to incorporate some means of hanging or using the silver object such as wire handles on an amphora. Alternatively you can drill a hole using a toothpick or skewer through which a silver "jump" ring can be inserted. Make sure the paste is very thick around the hanging hole. Beads can be left on the skewer or gently removed for shipping and firing.
When you fire your cork and silver clay project, heat the kiln slowly. This is especially important for pieces with large cork cores because the burning cork can increase the kiln temperature close or up to the melting point of the silver, damaging or melting your silver project.
While it burns away, some smoke is produced. Always fire in a well ventilated room. Never open the kiln door while Cork Clay is being fired-the sudden influx of oxygen may cause it to burst into flame, possibly harming anyone standing in front of the kiln.
When fired, the cork burns away leaving a small amount of ash residue. The residue is easily washed away with water.
Last updated on Thu, September 17, 2009 by Metal Clay Guru