Sunday, February 27, 2011

What's the difference between stoneware (ceramic) clay and and polymer clay (also known as Sculpey or Fimo)?

While we were working on a craft project, some kids in the neighborhood were asking me a very good question that I thought I'd share with you. What's the difference between stoneware (ceramic) clay that I use for my pottery and polymer clay (also known as Sculpey or Fimo) that we were using for our crafts?  The answer is practically EVERYTHING! I could understand their confusion since both substances have been called "clay," probably because they can both be molded/shaped and use heat to harden them. But as to how they are different:  ceramic clay is a natural mineral substance composed largely of silica (the same material that glass is made of) while polymer clay is not really clay at all - it is PVC (polyvinyl chloride) plastic (the same material your pipes may be made of). Although both are heated in the production process, stoneware clay is slowly, heated to 2260 F or higher (at which point it becomes very strong) while the Plastic clay is heated to 250 F (which is great because it uses very little energy and takes very little time.)  When stoneware is "glazed" it is coated with another clay that is even higher in silica content, which, when heated (fired) to to temps above 2200F, becomes  extremely hard and glasslike and  which makes it "waterproof" in the glazed areas. When plastic clay is "glazed," it is coated with  acrylic which is not baked.  While ceramic clay bodies only have the vibrant colors available with plastic polymer clay when they are glazed, one of the main advantages of natural ceramic clay is that it is a material known and proven to last the ages (centuries). In today's throw away society, it's nice to know that your stoneware clay product  has the potential to be passed down to future generations, and if it's handmade also, it will be something to be treasured!

 This is a new piece; sort of a bizarre, out of the ordinary, tea light/luminary. It was hand thrown, altered while wet, and then carved when leather hard. It's glazed with a commercial glaze, Coyote's gun metal green.  (we usually use our own glazes, but this one is so cool!)

EMT Etsy Mud Team Challenge! Today's the last day to vote in the Platter Challenge.  (Voting earns you a 20% off coupon to participating Etsy Mud Team shops, of which Hurricane Pottery is one!)