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Between the Lines: Grouting Tiles, Mosaics, and Tile Installations for a Visually Pleasing Effect
Posted By Laura Reutter On December 22, 2010 @ 8:00 am In Ceramic Decorating Techniques,Daily,Features,Making Ceramic Tile,Pottery Making Illustrated | 12 Comments
Grout does not just have to be a practical element in tile work. With a wide range of premixed grout colors available, it can also be used to aesthetically enhance a single tile or an entire tile mural. By strengthening the weight of a line or adding a weathered patina, grout can really become an integral part of the decorative process.
Today, Laura Reutter demonstrates how grout can be used in this way. She also gives some great advice for press molding and drying tiles without warping. – Jennifer Harnetty, editor.
Grouting for effect isn’t a new idea—several tile companies around the turn of the last century used grout in decorative as well as functional ways, including Moravian Tile Works and the Hartford Faience Company.
Grout is a mixture of cement, sand, and colorant to which water is added. Like mortar, grout hardens slowly over a period of time. In conventional tile installations, grout fills the spaces between ceramic pieces, creating a smooth durable surface that prevents the penetration of moisture and dirt. Grout is available in a wide range of premixed colors, making it easy for artists to pick and choose the appropriate hue for their project.
To achieve a decorative effect, tiles require recessed areas in their surface that will hold grout. These recessed areas may be linear elements such as grooves or negative shapes carved into the tile. Grout is applied to the tile after the glaze firing. Gaps between whole tiles and tile mosaics also create grout lines. Depending on the width of the grout line, the effect can range from subtle to dramatic.
The following examples focus on using charcoal black grout applied to the surface of glazed stoneware tiles that have been fired to cone 6.
The swan tile (see page 30) is a simple 4×8-inch tile based on an Art Nouveau period design. First roll out a ½-inch thick slab of clay that’s large enough to accommodate the design. Make the paper pattern slightly larger than the final tile size to allow for shrinkage during drying and firing. Transfer the image to the clay slab by tracing over the paper pattern with a pencil, pressing firmly to ensure the design is inscribed into the clay.
Cut the slab to its desired size and allow it to stiffen overnight. Once the clay is almost leather hard, incise narrow lines—approximately 1/16-inch wide and 1/8-inch deep-—around the primary shapes on the clay tile. Use a combination of wooden and metal clay modeling tools and bamboo skewers to create the lines. Add additional linear details to the swan tile, such as feathers and ripples in the water, if desired. Keep in mind that the wider and deeper the incised line, the more grout it will hold and the more prominent the grout line becomes. Extremely shallow details will not retain the grout.
Brush, pour or dip glazes onto the tile, taking care not to fill the grooves. After glazing but before firing, any glaze drips that have settled into the grooves must be removed using a needle tool or pointed wooden stick (figure 1). Grout won’t stick in a shallow groove that’s partially filled with glaze. Once the tile has been glaze fired, it’s ready to accept grout.
Note: Colored grout stains everything it touches! Protect your work area with plastic sheeting or newsprint and wear gloves. In addition to the grout, available in home centers and flooring stores, you’ll also need a sponge, container of water, container for grout, stirring stick, and a flexible squeegee for application (figure 2). Mix the grout as instructed by the manufacturer and apply to the surface of the tile.
Once the lines are filled, the grout should be left undisturbed in order to set up. After 30 minutes or so, sponge off any excess grout. Use a slightly damp sponge and be careful not to lift grout out of the grooves (figure 4). If you do accidentally remove too much grout, you can add a little where needed at this time.
There will probably be some alteration of glaze colors during grouting. Light glazes and matte glazes are especially prone to picking up colors from grout. Test a sample of your glaze with some grout first if you want to avoid unexpected color shifts. Areas that are sensitive to staining may be coated with a resist such as paste wax or varnish prior to applying grout. Again, testing is recommended.
I found that the white glaze on the swan’s body was readily stained by the black grout, but I wanted the grayish muted effect that resulted and did not mask this color (figure 5).
My Idyll tile was designed specifically to utilize black grout lines that would strengthen the composition, enhancing an already linear Arts and Crafts-style image.
The first step is to establish a basic pattern on paper. Use a wide-tipped permanent marker over a pre-existing drawing to give an idea of how the final grout lines will look. Trace the pattern using a stylus, transferring the design to a stiffened clay slab. Once the design is established on the slab, carve grooves to a width and depth of at least 1/8 inch (figure 6). The grout requires a groove deep enough to anchor it, ensuring it will stay in place during application and sponging.
As described above, apply grout liberally and use firm pressure in all directions. Sponging off the grout reveals dramatic changes in the appearance of the tile.
The finished tile will probably appear darker and/or more muted than the original due to coloration from the grout. This is normal and part of the charm of the process. The addition of black grout lines strengthens this composition greatly. Compare the photograph of Idyll before and after grouting.
My goal in designing Reverie (see above) was to produce an effect similar to a stained glass window. Strong grout lines form an integral part of the composition much like lead lines do in stained glass.
Reverie is a multi-part tile assemblage measuring 12 × 17 × ½ inch. Its four press-molded sections have grooves approximately ¼-inch wide and ¼-inch deep to accept grout. The 20 border pieces are made separately from stiff clay slabs cut to size. I used a decorative stamp to impress a rose motif at the corners.
In this example, grout fills the grooves in the tiles, gaps between molded sections, details in the face and hair, as well as filling in the letters of Reverie—producing positive letters from a carved negative space.
For a multi-part project, all the glazed pieces must be adhered to a support before grouting. Suitable supports include plywood, mold resistant drywall, cement board, brick, and concrete. Depending on the support chosen, prep work may be involved, such as sanding painted surfaces. There are tile adhesives available for every need. Check your home center and follow the instructions provided with the adhesive. I prefer to use water-based adhesives, which give off less odor and are easier to clean up. Spacing between sections is an important consideration; it should be consistent and pleasing to the eye. Remember that gaps become dark filled in lines and play a big role in the final appearance of your project. Tile adhesive doesn’t set up instantly so you have time to adjust the placement of individual pieces if you don’t like the initial placement.
I’ve enjoyed experimenting with the possibilities of grouted tiles and look forward to further explorations.
Tile artist Laura Reutter has been designing and making tiles since 1998. Her business, Ravenstone Tiles, is located in Port Townsend, Washington. Visit her website at www.ravenstonetiles.com for more information.
Pressmolding and Drying Tile
Keeping tiles flat while drying and firing has often been a source of frustration for clay artists. I’ve read a lot about sandwiching wet tiles between drywall, flipping them and stacking them endlessly until they are dry. This is inefficient and not cost-effective for tile makers. Here’s a technique that greatly minimizes the amount of handling needed and is almost foolproof for making flat tiles.
To begin, roll out a 1- to 2-inch-thick slab of clay. Using a heavily grogged clay formulated for sculpture or tile—not a plastic throwing clay. Choose a dry, stiff clay, as too much water makes the tile dry slowly and promotes warping.
Work the clay slab into the mold, pressing the clay by hand (figure A). Roll firmly over the back of the mold with a rolling pin, pushing the clay into all the recesses. Trim the excess clay from the back of the mold with a wire tool (figure B). Allow it to dry for one to two hours. Remove it from the mold by turning the mold over, holding it above a sheet of drywall, and gently tapping on the bottom (figure C). Avoid over handling the tile at this point. If you do move the tile, the clay’s “plastic memory” will kick in and it may warp during drying and firing. After trimming any excess clay from the top and sides of the tile, it is very important to allow the wet tile to sit on the drywall for 8 to 12 hours (overnight is usually good). Drywall sucks a lot of water out of the clay and the tile will really stiffen up. By the next day the tile should be pretty close to leather hard and stiff enough to handle without flexing. Now trim and smooth the edges.
There’s no need to score the backs of tiles unless you want to. Scoring has nothing to do with the warping or drying process, but it helps the tile adhesive cling to the tile and hold it to the wall or floor during installation.
Once the tile is trimmed, place it directly onto a drying rack (figure D). The bars of the rack need to be fairly close together to support your tiles fully, yet still allow air to circulate between them. Because air circulates on all sides of the tile, it dries very evenly and no warping occurs. No flipping, covering, weighting or stacking is needed. While your tile dries, avoid direct sources of warm or flowing air onto the tile, again to avoid warping. Keep the tiles on the rack until they are completely dry and ready to bisque. The tile, depending on you room environment, may take up to a week to completely dry without warping. Again, avoid over handling of the tile.
Fire the completely dry tile flat on the kiln shelf both for bisque and glaze firing. During the bisque, tiles can be stacked two deep. You might be able to stack them three deep if your tiles are on the thin side. Don’t make stacks that are higher than 1 inch.
For more tile and mosaic projects be sure to download your free copy of How to Design, Make and Install Ceramic Tile Murals and Mosaics: Design Tips and How-To Instructions for Handmade Ceramic Tile Projects.
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