Glass Coating Ceramics
Step 1 This project can be completed with a hand-thrown bowl made on a pottery wheel or with the assistance of a plaster slump mold. If throwing the bowl on a wheel, construct a bowl or plate of your desired shape and size. Since part of the bowl will be carved away, ¼ inch thickness is suggested. If using a slump mold, begin with step 2.
Step 2 If beginning with a wheel-thrown bowl, skip to step 4. Roll a clay slab (large enough to cover the slump mold) with a slab roller or rolling pin and cut it to the shape of the slump. Since part of the clay will be carved away, it’s best to roll the slab to around ¼ inch thick.
Step 3 Drape the clay slab inside the slump mold and use a towel to press the clay down against the mold. Press out any folds in the clay.
Step 4 Use the Soft Fan to apply one coat of White to the inside of the bowl. (Don’t worry if it has some streaks or if some of the red clay shows through the white.) Allow to dry to the point where the wet, shiny look is gone.
Step 5 Use a wooden rib to make indentations along the outer edge of the bowl.
Step 6 Pull up along the edge of the bowl to create a bit of a ruffle all the way around the shape
Step 7 Center the slump mold (with the pressed clay shape inside) on the pottery wheel. If you started with a hand-thrown bowl, it should still be centered on the wheel. Start the wheel turning at a comfortable speed and use a variety of ribbon tools to carve grooves about 1/8 inch deep where the glass frit will be placed. Carve additional lines around the edges and between the carved areas where frit will not be added. Glass frit can only be placed on flat areas, not on the sides since it can slide or move in firing when placed on vertical surfaces.
Step 8 Remove the shape from the wheel or from the slump mold and place on several layers of newspaper or on a piece of drywall. Allow to dry thoroughly.
Step 9 Once it is completely dry, fire to cone 04.
Step 10 Apply one coat of Tuxedo to the entire surface of the shape. Use a damp sponge to wipe back the Tuxedo, leaving color in the crevices and grooves. Let dry. Apply two coats of Natural Clear to the front and back of the shape.
Step 11 Fire to cone 06. The above image shows how the piece looks before adding glass.
Step 12 Use a spoon to scoop frit into the carved-out areas. Overlap each color slightly so it looks like one color flows into the next. Use the Wipe Away Tool to push loose frit into position. Heap the glass since it will compress slightly when fired and thin areas could expose ceramic surfaces.
Step 13 Stilt the bowl and place it in a kiln, and fire at 500 degrees per hour up to between 1,400 and 1,450 degrees Fahrenheit. You don’t want to heat the glass to the point of completely melting. It should be heated to the point of tackfusing where the glass softens enough to round edges and bond to the ceramic surface. Every kiln fires differently, so start looking inside the kiln at around 1,400 degrees and turn the kiln off when it reaches the proper fuse.
What did you learn from this project?
• Glass can be tack-fused to ceramic surfaces, giving a textured surface.
• Glass frit can be full-fused to ceramic shapes for a smooth finish. The glass will usually have a crackle pattern since the C.O.E. of clay and glass vary.
Note: Creations like this are designed for decorative purposes and are not safe for food.