View Larger Image Detail of the restored coal-saggared tile floor, which occupies 350 square feet in St. Athanasius' Chancel, Evanston, Illinois.

April 1, 2007

The Dark Side of Athanasius

by Brian Fiorentino | Read Comments (1)

From Dante to Lucas, it’s the dark side that provides much of the texture to our journey. I hadn’t quite reached this epiphany when I first gazed at the patterned tile beneath my feet in the dimly lit chancel of St. Athanasius Parish. Now with the sting of smoke still faintly in my eyes, I recall the dark swirling fumes from which the tile was born. I think of Hamlet’s witches chanting over a smoking caldron and recall Hamada saying, “if you truly want to know what happens inside the kiln, you must go inside.” Though I never fully realized that feat, many an hour was spent coaxing visions of darkness from inside the coal-filled saggars spewing smoke from my kiln.

The spirit of the great medieval polymath St. Athanasius was near as I strode the aisle of his namesake church with a group comprised of two architects, a priest and an engineer. Beneath our feet was a tile floor, installed eighty years previously and hidden under tattered carpets for almost half that time. The architects had been looking for a year for someone to restore the floor, and now regarded me with a mixture of skepticism and vague expectation. But there in that religious edifice I suddenly found myself on familiar ground.

A few weeks earlier I had come across a Ceramics Monthly article on red clays (“Red Clays for Mid-Range Oxidation,” by David G. Wright, March 1999) that mentioned the passing of an old clay mine. The orange clay that was mined there was called PBX Valentine. It now lay buried beneath a vast shopping mall in northern New Jersey, lost forever to the hands of potters, sculptors and brickmakers.

It was my favorite sculpture clay throughout the ’80s until it was no longer available. The group assembled at St. Athanasius that day were taken aback when I named a town in New Jersey where I thought this tile may have originated. It was only speculation, of course, but the color was unique and so familiar to me that it seemed a distinct possibility. The article mentioned a possible replacement, so I left them with some hope of finding a good match, and we struck a bargain to begin producing samples.

Looking at the tile of St. Athanasius, I had but to connect the dots of past and present to find a solution. I placed calls east and west to some of the old practitioners of our art. I also managed to reach the author of the CM article to ask about a substitute clay. Gradually I assembled my sources.

I found my own twenty-year-old clay recipe on a receipt from the “Grinding Room” at Alfred University. The junk I keep justifies its existence at rare intervals. The new recipe would be a combination of science and intuition. The heft of the tile told the density; the grain of a broken shard revealed the grog content; I estimated the shrinkage and temperature from the color of the fired clay. The architects had asked for samples within two weeks and I delivered. Even I was surprised by the strong resemblance. One architect gasped, and they got confused over which was the original. They were impressed with the apparent sleight of hand and regarded me now as magician as much as tilemaker.

A Date With Darkness

With the orange recipe (link to recipe file) well under way, I squared off with the dark side of the project. These tiles were impregnated with carbon; a deep, smoked-in black for which there was no comparable pigment. But the gods of serendipity were fast at work, and experiences new and old made for a remarkable synergy.

I visited the Moravian Pottery and Tile Works in Doylestown, Pennsylvania. The staff there gave me a tour and I made note of the coal saggars they used, and the cutters designed for tile production. A few months later, they also generously shared a recipe for making saggars, and provided instruction on using horse bedding and coal dust to smoke tile. I admired their mottled gray-black tile, but was concerned about the random result. My tile had to be as black as black’s shadow, as impenetrable as night’s last hour.

 A search for horse bedding ensued and I found a dealer in western Illinois that sold horse bedding by the semitruck load. Next I set out to locate some coal dust. It was a cool, rainy day when I made my way through a labyrinth on the far south side of Chicago. I arrived with anticipation at the Gruen coal yard, only to find no one home. I stood there in the rain, empty bucket in my hand, while a frothing brace of dobermans thrashed violently against a chain-link fence wishing to strip me of my soul. I had cash in pocket, but Mr. Gruen had forgotten our assignation to trade in dark substances. After an hour, and with the dogs’ palpable ferocity bearing down on me, I nervously shoveled some wet coal into my bucket and quickly left. Later that season I would return to make a legitimate transaction, but for now I had what I needed for a test.

The coveted sawdust of the required size, shape and hardwood composition originated conveniently in a cabinetmaker’s shop five minutes from my home. The gods of serendipity smiled again but it would soon be the more fractious kiln gods that I would have to face.

Some nights I lay awake thinking about my invisible partner in the project; the tilemaker that preceded me by 100 years. There was a fine craftsman’s sensibility teamed with industrial precision that produced a one-of-a-kind, yet remarkably uniform product. Glidden/Claycraft was stamped on the bottoms of certain tile shapes. Claycraft was the name of a nineteenth-century tile company in California, but their company logo and tile products didn’t match the Athanasius tile. I searched but couldn’t find information on a tilemaker named Glidden. The maker of the original tile would remain a mystery.

The Moravian recipe for saggars was loaded with fire clay, talc, mullite and wet wood chips. Slabs were carefully packed into wooden forms and meticulously reinforced, smoothed and squared off. Lids were carefully fitted and the group of saggars was set aside to dry for a couple of weeks. After firing, they would be ready to pack with horse bedding, coal and tiles, and set in the kiln for the first tile firing.

If at First You Don’t Succeed . . .

The first saggar firings were a disaster. The new tile had to be fired between Cones 6 and 7 to match the density of the original tile, but none of the saggars withstood the stress of the higher firings. They cracked violently across the bottoms and up the sides, and the rush of oxygen leaking in turned the tile gray. It took another four weeks to master the twin beasts of stress fractures and deep reduction.

With the deadline fast approaching, I still only had about a 40–50% success rate with the black tile. Both the initial body recipe and design of the saggars were scrapped and rethought from scratch. In the end, I adapted a 1950s ?ameware body from Karen Karnes for the saggars. This remarkable body seemed to get stronger with every firing. I made detached slabs for the bottoms because even corderite kiln shelves had exploded from the extreme heat differential. I designed the lid to drop inside the saggar to compress the fuel as it burned so oxygen didn’t seep in and reoxidize the tile. All the seams and inside spaces were buried in sand because the clay seals I used shrank and cracked, allowing air to leak in.

The final hurdle was determining how to pack the tile inside with the fuel. A mixture of sawdust and coal was required; however, if the coal came in direct contact with the tile it left a hard, shiny residue. Sawdust alone would not develop the dense blacks required at Cone 6. Each tile had to be packed with a thin layer of fine sawdust on top, and then a careful blend of coarse horse bedding and coal dust around the edges. Sand was used to fill any remaining air space, and the tile was packed face to face, one on top of the other all the way to the top, with the drop-in lid applying pressure to the top layer of tile.

I recalled some research done at Alfred University by Charles Binns. He explained that terra sigillata reduced more easily than the clay body it was applied to. When I coated the tile with a light spray of terra sigillata made from my tile body, I finally arrived at a reasonable success rate. The tiles were coming out with a solid uniform black, and a hardness, density and size to precisely match the originals. I still have no idea how the original tilemakers achieved this result. The process of packing the tile in saggars was painstaking and unbelievably time consuming. It was hard to imagine someone devising this technique by choice.

 The last firing was to hold nearly a third of all the black tile shapes. It took two full days to load and was a work of art in itself. When the kiln was finally unloaded I was stunned at the results. This final batch of tile was a perfect uniform black, but was even darker than the original tile and would stand out in stark contrast. The reduction had been too successful! Just days before all the tile was due, a third of the black tile would have to be redone.

A Final Attempt

At this point I was physically and mentally exhausted. We had remade most of the black tile shapes more than once, completely remade the saggars three times, and now I had run short of materials. The summer was coming to a close, all five of my crew had left town, and I had seriously injured my back while loading saggars. But September weddings had been scheduled at the church and they expected the chancel to be finished. Facing failure dead in the eye, I made the decision to reload those tiles one more time.

 First, I ground the remaining chunks of coal by hand with a brick. I slowly repacked each saggar with Zen concentration—too much coal and the tile were too dark, too much sawdust and they were too gray—any remaining airspace and the tile were ruined. Bits of coal had to be carefully brushed from the top surface of each tile before the next could be loaded. The difference was very subtle and I wondered at times if I was imagining it, but each tile was repacked as meticulously as a Tiffany egg.

 The final firing would be my reward. 100% of the tile was just right: a true carbon black, but not too dark! When the tile was finally installed, the people at St. Athanasius were deeply satisfied and grateful. Their church had changed permanently for the better, and I myself had been changed irrevocably in the process.