Glazing & Firing: Tips & Troubleshooting
Making ceramics is an interesting hobby. People create, glaze and fire ceramic pieces for home use or decoration. People new to ceramics learn by their mistakes, but some problems are easily avoided. Preparing the bisque pieces properly, glazing and firing clay or using simple basic techniques keeps many problems from happening.
Other People Are Reading
-
Before Firing Greenware
-
Firing greenware is the first step in the firing and glazing process. Greenware is uncooked ceramic pieces. Make sure the greenware is dry before firing. If it is cold to the touch, it is too wet for firing. If it feels warm, it's ready for the kiln. Wet clay explodes in a kiln, and destroys the kiln walls. Remove any rough spots on the dry greenware before firing using a damp sponge or brush tool. Removing the rough or sharp spots gets complicated after firing.
Preparing Pieces For Glazing
-
Bisque ceramics (ceramics fired one time) are ready for glaze, but the bisque needs cleaning before firing. Small bits of debris gets inside the ceramic pieces during firing, and cook into the glaze during the next firing. Before firing, turn the piece upside-down, and, gently shake out any debris. Rinse the top, bottom and inside of the ceramic piece, so any small specks of cooked clay rinse off. Wipe the bottom of the piece off with a damp sponge, and let the clay dry for about 15 minutes before glazing.
-
Preparing The Kiln and Glazing
-
Paint several thick layers of kiln wash over your kiln bottom and shelves before firing glazed pieces, so you avoid damaging the kiln. This keeps glaze from sticking to anything if it drips. Paint two to three layers of glaze over the ceramic piece. Make sure it dries between layers.Put the glazed pieces in the kiln with at least one inch of space between them. If the pieces touch, they cook together, and are bound together.
Fire Hand-Built Items Slowly
-
Firing hand-built items is tricky. Some people make thick layers of clay that dry slowly, but the outer layer feels dry. Put a hand built item on a shelf by itself in the kiln. Set the kiln to the lowest heat setting on your kiln, and let it heat for three to five hours. This dries the piece without making it burst. Damp ceramic pieces explode if cooked too quickly. Fire the piece normally after drying it in the kiln.
Firing Red, Orange And Yellow Glaze
-
Red, orange and yellow glaze gives all potters problems. The red and orange changes to different colors if it's cooked with certain other colors, is low on oxygen or is cooked on stoneware clay. Make the ceramic piece out of white clay. It keeps the glaze from changing colors. Remove the plugs from the kiln before firing, and prop the kiln open a few inches with a stilt. This gives the kiln more oxygen. Fire the kiln to the cone listed on the glaze. The cone is a pyramid shaped object that is put in the kiln setter. When it melts, the kiln shuts off automatically at the correct temperature. Different cones melt at different temperatures. If you fire the glaze too high, it turns white with black lines through it. Never fire metallic glazes with red, orange or yellow glaze, especially copper colors. It makes the colors turn weird colors. Instead fire the glazes first, and paint an enamel metallic color where you want it after firing.
Cooling And Unloading The Kiln
-
Never open the kiln directly after firing, it takes at least six hours before the kiln cools enough for opening with a pot holder on your hand. Let it sit at least eight hours before opening the kiln with your hand. If you are firing glazed pieces, let the kiln sit for at least 10 hours before opening the kiln. Opening the kiln too early results in crazing. Crazing is when lines show up all through the glaze, and, sometimes, the glaze pops loose.
-
References
- Photo Credit Hemera Technologies/PhotoObjects.net/Getty Images
