Porcelain clay makes the most elegant tiles. Its natural buttery consistency creates a jewel-like surface when it has been glazed and fired. That's because the particles in the clay are so fine -- unlike tiles made from stoneware and earthenware, which have a more earthy, rugged look. Because porcelain is so refined, it requires attention and care to ensure tiles made from it dry flat and fire flat in the kiln.
Things You'll Need
- 1 bag moist porcelain clay
- 1 foot squares of canvas fabric
- 2 strips of wood 1/2 inch by 1/2 inch
- Rolling pin
- 12-inch ruler
- Paring knife
- 6-inch-wide putty knife
- Small pail
- 90-degree plastic triangle
- Plaster wallboard 12 by 12 inches in sets of two
- Thin plastic sheeting
- Spray bottle
- Metal cookie cooling rack
- Boar's hair and sable brushes
- Colored glazes
- Synthetic sponge
- Small natural sea sponge
Make A Plain 5-Inch Square Tile
Lay out a clean square of canvas on the work surface. Taking 1 1/2 lbs. of moist porcelain clay, roll it into a ball and set it in the middle of the canvas. Using the heel of the hand, pound the clay into a flat, square-like slab about 1 inch thick. Set one strip of wood on either side of the clay, making sure the distance between the two are no farther apart than the width of the rolling pin.
Roll back and forth over the porcelain, applying firm pressure, until the rolling pin makes direct contact with the tops of both strips of wood simultaneously. The clay slab is now 1/2 inch thick.
Remove the two strips of wood and lay the 90-degree triangle on the surface of the slab, making sure not to dent the slab's surface. Lightly run the tip of the paring knife along the two right-angle edges of the triangle. Carefully lift the triangle off the slab.
Measure out 5 1/4 inches from the two incised lines created by the tip of the paring knife. Make a slight dot in the clay with the tip of a sharp pencil every time you make a measurement. With measuring complete, lay the ruler along your reference dots in the clay and run the tip of the paring knife lightly along the edge of the ruler incising a perfect 5 1/4-by-5 1/4-inch square on the face of the clay slab.
Pick up the putty knife and align the edge of the blade on top of one of the incised lines on the clay slab. Hold the putty knife straight up and down then slowly press down until the blade meets the surface of the table. Repeat this until you have a perfectly chopped square tile.
Gently pull away the leftover porcelain clay from the square tile. Smooth the edges of the tile with a small natural sponge soaked in water before draping a piece of plastic over the tile and let it sit for 24 hours.
Repeat steps 1 through 6 for each additional tile.
Drying Porcelain Tiles
Lift back the plastic to allow air to start circulating around each tile. Porcelain tiles can warp very easily if dried too fast. Check on the tiles regularly and watch for any warping. The drying process must progress at a snail's pace. Cover the tiles back up with plastic at any time the drying needs to be slowed to maintain the flatness of the tiles.
Watch for the tiles entering the leather hard stage. When a tile can be picked up by the edges and the clay maintains its shape, it's leather hard. Peel the canvas away from the back of each tile and set each one on a piece of plaster drywall. Lay a second piece of drywall on top of the tile, gently placing a weight on top of the board.
Remove the tiles from between the wallboard when they look dry but not chalk-white. Set them on cookie cooling racks for the final stage of drying.
Start loading the porcelain tiles into the kiln, laying each one flat on the shelves when they feel bone-dry to the touch and are chalk-white.
Bisque And Glaze Firing Porcelain Tiles
Set the porcelain tiles flat on shelves in the kiln and close the lid. Slowly increase the temperature of the kiln. A bisque firing should take six to eight hours depending on the size of the kiln and how many tiles are in it. Just as a tile needs to be dried slowly, a porcelain tile needs to be fired slowly, too.
Cool the kiln for 16 to 24 hours.
Take the fired porcelain tiles out of the kiln and begin brushing liquid glazes on to the surface of each one. The color and design options are endless.
Let the raw glaze dry thoroughly. Check for any raw glaze that's flowed down on to the sides or bottom of the each tile. Take a damp synthetic sponge and wipe off any glaze on the sides or bottom of the tiles. Load the tiles back into the kiln, making sure no tile touches another. Fire to the recommended glaze temperature, which takes six to eight hours.
Cool the kiln for 16 to 24 hours before taking the tiles out of the kiln.
Tips & Warnings
- To tell if a tile is bone dry, lay it against the cheek. If the clay feels cool, that means too much moisture is still trapped in the clay. Continue drying.
- Any clay shrinks as it dries and during the kiln firings. To end up with a 5-by-5-inch tile, start with a raw square of clay measuring 5 1/4 by 5 1/4 inches.
- When firing a kiln, make sure the room is well-ventilated so the noxious fumes don't collect inside the room.
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