How to Make Clay Tiles
By Laura Reutter
We've read a lot about sandwiching tiles between drywall (sheetrock), flipping them, turning them, covering them, etc. to prevent warpage. I can tell you that none of this is necessary. Why spend countless hours handling, coddling and fussing over tiles? Not efficient! Not cost effective for a professional tile-maker. I have developed a technique that is almost 100% foolproof for making flat tiles and greatly minimizes handling.
First, use a heavily grogged clay that is sculptural or tile quality, not a throwing clay (not plastic). I use an off-white stoneware called Crystal Stone that fires to cone 6. (I usually glaze fire to cone 5 - 6 after a bisque firing of cone 05.) Crystal Stone is available at Seattle Pottery Supply. I tested dozens of clay bodies before I found this one. It had the least warping and shrinkage of all their clays that I tried. I'm sure other pottery suppliers will offer something similar.
Second, I like the clay on the dry, stiff side. Too much water makes it dry slowly and promotes warping. Wedge it a lot if it is too wet.
Supplies you will need:
Several pieces of drywall (small enough to handle easily--18" by 24"). Tape the drywall edges with duct tape to avoid the nasty plaster interior from leaving dust everywhere.)
Rolling pin or slab roller
A pattern slightly larger than the final size of tile you want. (My clay shrinks about 10%, so I make my pattern large enough to compensate for that.)
A couple of sturdy metal racks, the type you find for closet organizers (available at Target, K-Mart, or hardware stores). The racks are used for drying. An oven rack might also work. The bars need to be fairly close together to support your tiles fully. (Tip: thrift stores, junk stores, and salvage stores often have these racks for sale at a fraction of the retail cost.)
To begin, I cut approximately 1"-thick slabs off my bag of clay. Wedge the clay as needed. Then I hand-roll the slab with a sturdy rolling pin in both directions to get the approximate thickness needed. Most of my tiles are press-molded in plaster molds. If you use molds, drop your completed tile right onto a piece of drywall as it releases from the mold.
If you don't use molds, don't worry. The tile making process works the same way without molds. Just roll out your slabs directly onto a piece of sheetrock using wooden spacers or dowels under your rolling pin for the correct thickness. (I like 1/2"-thick tiles myself.)
Once you have rolled the clay slabs out, don't move them! Don't lift them or turn them or anything. (If you do move the clay, it will remember and will warp, bend, and curl during drying and firing.) Just trim the slabs in place, cutting them to the desired dimensions using your trimming knife and pattern. Remove the scrap clay around the edges and re-wedge. Allow the tiles to sit on the sheetrock for 8 to 12 hours, give or take a couple of hours. (Overnight is usually good.) The drywall will suck a lot of water out of the clay!
Now your tiles will be stiff enough to handle without flexing; test a tile and see if you can pick it up safely. At this point, trim and smooth the tiles' edges, and then place them directly onto a rigid metal storage rack. Because air circulates on all sides of the tiles, they dry very evenly without warping. No flipping is needed. No covering is needed. No weighting or stacking is needed. Keep the tiles on the rack until they are completely dry and ready to bisque fire.
There is no need to score the backs of tiles unless you want to. This has nothing to do with the warping or drying process. It helps the tile adhesive cling to the tile and hold it to the wall or floor during installation.
In all, you should need to handle your green tiles only about three times: once to roll out and cut the clay, once to smooth the tile edges and place the tile on a drying rack, and once to put it into a kiln for your bisque firing.
I fire tiles flat on the kiln shelf both for bisque and glaze firing. I have made tiles by the thousands, big and small, and perhaps have a warped tile once in every hundred.
Other notes: While your tiles dry, avoid direct sources of warm air (like a register vent or portable heater) that might dry one area faster than another. You want nice, even drying, at top and bottom. At 55 to 60 degrees F in my studio, my tiles take about a week to fully dry with no warping. If you want to hurry the drying you may use a fan to gently circulate the air in the room; this might dry the tiles in a few days. Drying will be slower in a cool, damp environment.
I built my tile drying rack from two shelf units made of rigid metal rod. Each shelf unit measures 12" wide by 36" long. My two racks are supported side by side on a wooden framework with legs. The total drying surface from these two racks is 24" wide by 36" long. It will hold quite a few tiles. It’s good to have the racks well off the ground and to allow plenty of air to circulate. Because I make lots of tiles, I bought enough racks to have several levels available to dry tiles, all supported by the wooden framework. (You could support the racks between two chairs or counters or improvise something if you don't want to build a permanent drying rack.)
Laura Reutter Ravenstone Tiles 1633 Cherry St. Port Townsend, WA 98368 www.ravenstonetiles.com firstname.lastname@example.org
Laura, it was very kind of you to share your experience in making tiles. Thank you.
The topic of tiles takes me back to my childhood. When I was 11 years old living near Tripoli, Libya, I could see the glittering Mediterranean from where I lived. In the early mornings I would walk along the beach collecting 1/2”-square Roman tiles that occasionally washed up on the sand. They had once decorated the ancient coastal cities of Sabratha and Leptis Magna.
Charles Hall sent a note about glass cracks: “If the crack is ‘healed,’ meaning the edges are softened, it means it cracked on the way up and then melted together at slump temperature. If the crack is sharp and distinct, it broke below fuse temperature (approx 1100 degrees F) on the way down. A crack can also be due to incompatible glasses.”
Last week’s Kiln Pointer included a letter from Don Pearse about quenching silver clay. Martha Biggar of Biggar Handwrought Jewelry in Draper, Virginia, adds more details: “Before you quench PMC or Art Clay, be sure to let the silver lose its cherry red glow. Quench in water. Also remember to NOT quench any metal clay with inclusions like natural or synthetic stones or glass. This can cause the inclusion to crack out. While stones do not have to be annealed, glass does.”
With best wishes,
Arnold Howard Paragon Industries, L.P. - Better Designed Kilns 2011 South Town East Blvd. Mesquite, TX 75149-1122 Voice: 972-288-7557 & 800-876-4328 / Fax: 972-222-0646 email@example.com / www.paragonweb.com
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