Slip Casting/ Ceramic Sculpture

WHAT IS SLIP CASTING? Slip casting is a process of creating ceramic forms by casting liquid clay (slip) into plaster molds. This process is most useful when you want to make multiples of a form. The molds enable you to create identical copies. —————– In the classroom, slip cast multiples can be used to†¦. -create multiples of a student’s ceramic artwork (for gift giving or a new sculpture of multiples) -create identical starting forms that students will manipulate to create their own unique artwork – try out different glaze techniques on – allow experimentation without the fear of â€Å"ruining† the artwork Materials All you need for slip casting: Plaster mold, Clay slip, kiln Necessary items if you want to make your molds: five gallon bucket, plasticene ( non hardening clay), Vaseline /liquid soap, hammer , chisel/screwdriver, —– Plaster and slip are available at most ceramic supply centers. I listed some local suppliers on the resources page in this packet. Plaster comes in a couple different types. Pottery plaster is the standard and readily available at ceramic supply stores. Casting plaster is only necessary if you want to make extremely detailed pieces. I go with the cheapest and it works fine for classwork. Just as  clay comes in many forms, so does slip. The texture and chemical content of the slip dictate what type of clay body it forms. Clay slip bodies range from fine delicate porcelain to coarse strong stoneware. Your firing temperature depends on the content of your slip. For normal classroom use I use low fire white casting slip. It is available in premixed 2gallon bags from most ceramic supply stores. It usually runs about 8 dollars a bag. Four gallons is enough for a class of twelve to make at least two ten inch hollow forms. HOW EXACTLY do you CAST SLIP? First, you need a mold made of plaster. It must be plaster because the plaster absorbs the water from the slip. Fill the mold with slip. As the mold absorbs the water, the level of the slip in the mold will go down requiring you to top off the mold. You want the slip to stay level with the horizontal surface of the mold. If you want a hollow form , you have to dump out the excess slip. Watch for an eighth of an inch skin of slip to form on the edges of the piece before you dump the slip. That skin is now the wall of your hollow piece. For small pieces, it only takes about five minutes before you are able to dump out the excess slip. If you leave a mold filled with slip too long, the ceramic piece will be thick and heavy. Which doesn’t really matter, but it wastes a lot of slip. If you don't leave it in long enough, it will tear as it comes out of the mold and be useless. You can pour solid. Usually this practice is used for plates, bowls, and other utility items. To pour solid, just keep filling the mold with slip until it stops sucking up slip. [pic] HOW DO YOU get the piece OUT OF the MOLD? After you have dumped the excess slip, the mold has to sit and dry. The mold pulls the water out of the clay and dries the piece out. To speed up the drying you can use a fan, blowing across the molds, or put your molds on top of a hot kiln. The larger the piece the longer it will take to dry. If you leave a piece in the mold too long, it will dry out too much and crack. If you don't leave it in long enough, it won't come out easily and will tear. You can tell if a piece is ready to come out of the mold if it has pulled away from the sides of the mold/pour hole. When the casting is dry enough to take out, gently pull your casting, now more like leatherhard clay, out of the mold. It should release easily, if the piece is dry enough. Try to pull the piece straight out of the mold to keep from warping its shape. When the piece comes out of the mold it will be a dark gray. Once out of the mold it will continue to dry and will turn light gray. After the piece has dried to a light gray almost white, it is ready to fire in the kiln. Adapted from: http://www. rykerstudios. com/ceramics/articles/slipcasting. htm RESOURCES Casting Slip Available in Atlanta from: — Daven’s Ceramic Center http://davensceramiccenter. com/ 5076 Peachtree Road, Atlanta, GA   30341 Fax:   770-455-7012 4805. Atlanta Area   770-451-2105 [email  protected] om Casting Supplies ONLINE — Axner Ceramic Supply http://www. axner. com/axner/supplies/slip-casting. php — mold making and casting materials http://www. smooth-on. com/ How to Resources: Trouble shooting guide- http://aardvarkclay. com/pdf/technical/Basics%20of%20slip%20casting. pdf Short History of slip casting- http://www. lindawilsonceramics. co. za/3. ht ml Deflocculation of slip-(make your own)– http://ceramic-materials. com/cermat/education/213. html Videos- YouTube Video- http://www. youtube. com/watch? v=8u_SABU_8d0 Advanced mold making video demos- http://www. smooth-on. com/media. php