Cookout season is upon us, so I thought I would pass on a somewhat cookout-related project for this Monday morning.
When potter Clay Cunningham lost his glass patio tabletop in a spring storm, he decided to keep the existing table frame and replace the glass top with a ceramic mosaic top. In this post, Clay explains how he did it, from the planning stages to the final grouting. Plus he shares his clay body and clear glaze recipe. – Jennifer Poellot Harnetty, editor.
I recently returned from a vacation to discover that a spring storm had destroyed the glass top of my patio table. I was faced with two options—order a new manufactured tabletop or put my talents to work by designing and building a new one out of clay. With my summer schedule open, my wife and I started our mosaic table. This is a great project for use in any outdoor setting.
Creating the Design
Begin by purchasing a 5/8-inch thick sheet of exterior plywood. Cut the plywood to the shape of the table frame with a hand-held jigsaw. You can also use a hole saw to cut a hole in the middle for an umbrella to fit through. Once the plywood is ready, start designing the mosaic.
Lay the plywood on the floor, cover it with large sheets of drawing paper (24 × 36) and lightly tape them together to hold their position. Cut the paper to the shape of the tabletop and sketch a design in pencil (figure 1). We decided on an image of aspen trees with beautiful red and yellow fall leaves, but any image is possible with this technique. There are a few considerations when designing a mosaic. First, large clay tiles tend to warp, which leads to an uneven top, so keep individual pieces small—less than eight inches on a tile’s longest dimension. Second, the tiles fit together like a puzzle, but an excess of undulations causes trouble. It’s best not to have pieces lock into one another. Finally, including a border will not only visually ‘frame’ your design, but also ensure a nice, even edge to the entire table.
Finalize the image in pen and remove the tape carefully. Number the individual sheets to help keep track of their position. Also indicate the four quadrants of the plywood sheet as well.
- Drawing Paper
- Plywood Table Top
- Jiffy Mixer
- Tile Adhesive
- Wet sponge
- Needle Tool and Stiff Flexible Rib
Get Out the Clay
Roll out a large ¼-inch thick slab of clay (we used white earthenware). This will be thick enough for strength yet not so thick that it makes the tabletop excessively heavy. Now lay one quadrant of the paper out onto the clay and cut the edges to match the drawing. To ‘trace’ the image onto the clay, use a needle tool to do what I call the dot-to-dot technique. Simply follow along the drawing, lightly piercing through the paper with the needle tool until the entire drawing is perforated (figure 2). It’s important not to press down on the needle tool too hard. If you do, you’ll stab into the clay, which distorts the drawing and makes for rough, gouged edges. Remove the paper to reveal the dot-to-dot drawing on the clay. Continue this same technique with the other three quadrants.
Allow the clay to dry to an early leather-hard state then cut along the dotted lines with a fettling knife (figure 3). Check the cut pieces with the original paper design for overall consistency. After drying a bit more, smooth the tiles out along the edges and round off any sharp points. If the edges and points are not smoothed, they may turn into sharp areas poking out on your tabletop.
To prevent warping in the tiles, carefully flip and gently compressed each one numerous times over the course of a few days or dry them on an open wire rack. While the tiles are upside down, incise small grooves into the back of the tiles with an old pen. This groove allows the tile glue to grip and hold onto the tile. Do not use a needle tool to create the grooves as it will make a line that is too thin to allow the glue to fill the groove. When flipping the tiles, keep the them close together and in their correct position.
Glazing and Firing
Meticulous note taking is important when moving the tiles to the kiln shelf. Make detailed drawings of which clay quadrants are on which shelves and where the shelves are placed in the kiln. Without these notes, it’s easy to get confused. Space the tiles out a bit to allow enough room to add underglaze to them without accidentally getting the wrong color on a tile. Though you could add the underglaze to the tiles before placing them on the kiln shelf, placing them first avoids over handling of the underglazed pieces. With a wide hakeme brush, apply underglazes in a thick, opaque coat onto the tiles (figure 4). After the underglaze is completely dry, apply a thin coat of a clear glaze and load them into the kiln. You can bisque fire the tiles before glazing them if you wish, but I wanted to eliminate as many unnecessary steps as possible. Fire them slowly to the appropriate cone.
Prepping and Setting the Table
Brush three coats of weatherproofing water sealant onto the plywood tabletop to ensure its longevity. Gather the tile glue, grout, and trowels for creating your mosaic. All of these supplies came to less than $50 (including the plywood) and can be purchased at your local home center.
Now it’s time to construct your mosaic. Begin by laying the tiles out onto the plywood, allowing an even amount of space between each tile. Because the clay has a shrinkage rate of around 10%, the mosaic will perfectl
y fit your tabletop and allow just enough room between the tiles for the grout. Once the tiles are situated, they’re ready to be glued down. Flip each tile over, coat with a liberal dollop of tile glue (figure 5), and immediately place into position, paying careful attention to retain an equal amount of space between all of the tiles. Continue this process until every tile is glued and placed. I recommend going back over each tile and giving it a little wiggle to ensure that none are missed. Trust me, you’ll find one.
Allow the glue to dry overnight and add the grout the next morning. The grout does two things—first, it adds a stained-glass effect with all of the tiles separated by a single, unifying color and second, it keeps water and other materials from getting between the tiles and rotting the wood underneath. Note: If any water freezes between the tiles, it will expand and break the mosaic.
Grout comes in an unending variety of colors so choose the best color for your design. A black grout helps colorful tiles ‘pop’ out at the viewer. Mix the grout per the instructions on the package to a smooth, thick concrete consistency and immediately trowel directly onto the mosaic. It’s important to get the grout down into every nook and cranny between the tiles (figure 6). With one motion, press the grout down into the empty spaces. With the next motion, scrape it off of the top surface. Continue until the entire tabletop is coated with grout, including the edge of the table where the tile and plywood meet.
Though the table will look like a mess, cleaning it off is a snap. As the grout begins to dull in color, use a soft rubber rib to scrape it away from the top (figure 7). The scraping removes all but a fine film on top of the tiles which can be easily wiped away. Remember, it’s always important to wear a respirator or dust mask whenever handing dry materials. Last, a light sponging with a thoroughly rung out damp sponge brightens all of the colors and a dry towel removes any remaining film. The entire grouting process can be completed in less than an hour.
The only thing left to do is secure the tabletop to the table frame. Cut out small blocks of wood and insert wood screws into them. These serve as the brackets that lock the tabletop into place, yet allow it to be removed if needed. From under the table, place each bracket a few millimeters away from the table frame, one in each quadrant, and screw them into the underside of the tabletop. And with that, the table is complete.
|Clay’s White Earthenware Cone 04|
|OM4 Ball Clay||25|
|Carly’s Clear Glaze Cone 04|
|Pemco 626 Frit||25|
Add: Handful of Epsom Salt
Clay Cunningham is a ceramic artist and instructor, currently teaching at Lewis Central High School in Council Bluffs, Iowa. To see more of his work, or for contact information, visit www.claycunningham.org.
**First published in 2013