After we ran last week’s feature “Making Multiples: Cavity Molds for Handmade Ceramic Tiles,” we received an inquiry from a reader about making tiles for an outdoor installation. The reader wanted to know what type of clay she should use to ensure that the installation would withstand great temperature fluctuations.
To address this question, we decided to go to someone with a lot of experience in this matter: DeBorah Goletz. In 1998, DeBorah was commissioned to design and install a series of ceramic tile murals for the Sheepshead Bay Road subway station in Brooklyn. For this, DeBorah needed to do much testing to be sure the murals would survive New York’s hot, humid summers and its bitter cold winters. In today’s feature, author David Kaplan shares DeBorah’s testing methods. –Jennifer Harnetty, editor.
For her mural series “Postcards from Sheepshead Bay,” DeBorah decided to create her own handmade tiles in the style taught at the Moravian Pottery and Tile Works in Doylestown, Pennsylvania rather than going with the easy nostalgia of mosaic. She had visited the Moravian Tile Works in the early ’90s and became enamored of the puzzle-piece tile arrangements seen there. The Moravian-inspired method of interlocking tiles allows use of the grout line for the image. “One of the problems with tile,” explained Goletz, “is you always have to figure out how to depict something, but you also have to deal with the grout lines. You could just paint something on square tiles, but then you have this square grid going over your design. With the Moravian style, the grout line is totally integrated into the design.” While traditional Moravian tiles are not recommended for outdoor use because they are not frostproof, Goletz knew her tiles would have to face New York City’s oppressively hot and humid summers and its unforgivably frigid winters.
She began experimenting with a commercial body (417 from Standard Ceramic Supply in Pittsburgh) fired to Cone 02. At this temperature, the clay has an absorption rate of 1%, putting it below the 3% or lower required for tile to withstand frost. The absorption test Goletz used was established by the American Society for Testing and Materials. First, a fired tile is weighed dry (Wd), then soaked for 24 hours in cold water. Immediately after being dried with a towel, the tile is weighed again (Ws). The absorption rate is then calculated from the two measurements using the formula below:
“Selecting a glaze recipe was less scientific, but equally strenuous,” Goletz recalled. “Because thermal expansion is difficult to establish with matt glazes, I devised other ways to test the fit between the glaze and the clay body. I did a series of tests in my kitchen, including putting glazed tiles through a hot dishwasher cycle, then into the freezer for a day or two, then back into the dishwasher, and again returning it to the freezer. “I repeated this process eight or nine times, then checked for crazing, using a magnifying loupe,” she continued. “If no crazing showed up, I drew over the glaze with indelible markers, let it set for a couple of days, and used various cleaners—including those used by the MTA—to try to remove the marker.” Once the base glaze passed this rigorous set of tests, Goletz added various colorants. “I do a lot of experimenting. I keep all my glaze tests as reference for future projects,” she explained. “I prefer the depth I get using oxide stains rather than commercial stains. But when the desire for a particular color necessitates, I use Mason stains.” The completed murals were installed in 1998. Even when it was still in the construction phase, “Postcards from Sheepshead Bay” received an award for excellence in design from the Art Commission of the City of New York.
To see more images of DeBorah Goletz’s work, visit, www.forloveofmud.com.