Let There Be Light Curtis Benzle

Appears in the October 2022 issue of Ceramics Monthly.

Our daughter (Marisa) enjoys an occasional respite from her dawn-to-dusk career in commercial agriculture by renting space in a Gainesville, Florida, ceramic studio. Prior to becoming a full-fledged member of the Art Alley (and despite her lifelong experience in my clay studio) Marisa had to take an introductory clay class. Her teacher, a student at the University of Florida, mentioned his academic interest centered on translucent porcelain. And so, I thought . . . 

Another Moth to the Flame

Clearly, clay has qualities that tantalize and engage. My initial fascination was throwing on the potter’s wheel. That seemingly simple act of spinning a mass of malleable clay into a sumptuous form secured a lifelong obsession. While I never particularly warmed to glazing, that magical, Christmas-morning moment of opening a kiln still holds an addictive appeal. And then, perhaps most enticing, elusive, and possibly the least understood attraction—translucency.

The ability of translucent porcelain to manipulate and transmit light ever so seductively is a quality quite often misunderstood as low-wattage transparency. Transparent color explodes in refractory magnification and illumination. Translucency, an inherent quality of porcelain, is less celebration and more afterglow. It creates mysteries by challenging the eye, while imagery hides among the opaque shadows of thickened clay. 

Imagine the seductive sighting of a faint image, shrouded on a misty morning or fish, darting in dark and swirling waters. These are the moments that call for translucency—when our aesthetic objective is to embrace the emotion of a moment, instead of a precise repetition. 

Translucency is Magic and Mystery

My initial artistic pursuit of light and form emerged during my studies for an MFA in glass at the School for American Crafts at the Rochester Institute of Technology (RIT) in New York. While I embraced the many virtues of glass, I soon realized that being barred from the tactile connection with clay presented a major problem for me. So, I set off trying to blend the best of two worlds, the tactile quality of clay and the luminous character of glass. Porcelain was the clear solution.

At that time, 1974, there was not much information available about translucency in porcelain. Everyone who cared to look knew that a high-quality porcelain would transmit light, but how?
The popular formula for porcelain was 25 parts each of silica, kaolin, feldspar, and ball clay, but that formula yielded a rather dim luminosity. I was advised to remove everything that had any metallic content, so out went the iron-bearing ball clay. I increased the feldspathic fluxing agents in order to lower the firing temperature to a range that would achievable in an electric kiln and endlessly adjusted material ratios until I ended up with the highly translucent recipe I named Benzle #89. Along the way, I learned a lot about why porcelain is translucent. An out-of-print technical treatise, Clay Bodies, by Robert Tichane was chemically complex and confusing, but an invaluable resource. The following is a brief interpretation of his lengthy explanation.

Making a translucent porcelain requires a delicate balancing act with the constituent materials. The body needs to be dense, with the correct crystalline structure to provide an appropriate degree of both stability and translucency. The body also needs to melt, but not so much as to sag. Two concerns for maximum translucency and minimum slumping are viscosity and color:

• Viscosity: The viscosity of the flux needs to be as high as possible to inhibit distortion. The clay component will also impact viscosity, and New Zealand kaolin (a halloysite clay mineral) has an unusual crystalline configuration that promotes a stable structure. (I did not use New Zealand kaolin in the Benzle #89 clay body recipe as it was not available to me in 1975, but I do use it in the Benzle #108 clay body­—both recipes are listed on page 39.) 
• Impact of Color: Pure metallic oxides will absorb light and diminish translucency. A safe and simple workaround is to take advantage of the incredible work of ceramic engineers and use ceramic stains to add color. Stains are safer and less apt to block translucency. Stains should still be used with caution and tested for color stability and translucency.

It is challenging to achieve the precise balance between glassy transparency and ceramic viscosity, but when this balance is struck, the result is a material that whispers with a very subtle and sublime beauty.

Lithophanes

Along the path to translucent porcelain, it is difficult to miss an encounter with lithophanes. In 1984, following up on a tip from a librarian at The Ohio State University (OSU) in Columbus, Ohio, I visited the incredible collection of lithophanes amassed by Laurel Blair in Toledo, Ohio. Blair, a real estate agent by profession, was passionate in explaining his understanding of how lithophanes were made, but my working knowledge on the subject was more significantly informed by the doctoral thesis written by Walter Ford at OSU. Dr. Ford realized that while carving wax could be useful in the creation of lithophanes, the more common process was photographic.

Specifically (and outlined in an October 2007 article in Ceramics Monthly), a slurry consisting of gelatin, ammonium dichromate and water are mixed, dried on a glass plate, and exposed to intense light through a photographic negative. When rinsed in water, this yields a low-relief plate that is graphically consistent with the previous two-dimensional image. Because this photo process was difficult, messy, and slightly dangerous (due to the ammonium dichromate), I was pleased when, years later, I discovered the more technologically advanced method that incorporated digital imagery and a computer-numerically-controlled (CNC) router. CNC routers and digital printing are now used extensively in the creation of contemporary lithophanes. I carve into Corian plastic because it is approximately the same translucency as porcelain, so the image is visible upon carving. I carve a negative image in the plastic and then make a plaster mold from that. 

Over the years, I have enjoyed multiple uses for lithophanes in my production line of nightlights and architectural lighting. I find the lithophane integration of light and clay eternally fascinating and continue to explore.

Translucency and the Art World

A successful, translucent porcelain body, even when available, creates a curious cultural conundrum as translucency falls outside the normal, critical criteria evaluated in the visual arts. When observed, translucency is often admired, but this quality is rarely expected or critically considered. 

Translucent porcelain is ephemeral, with a luminosity that is only apparent under specific illumination. I embrace the aesthetic challenge of this transitory nature, but have learned over the years that most curators and collectors anticipate work that is experienced precisely as it looks under specific gallery lighting. This is a limited perspective, but one that is virtually omnipresent.

Translucency in porcelain is a prime example of an overlooked aesthetic virtue. While one of the hallmarks of porcelain (along with density and tone or ring), translucency is often misperceived as unrealized transparency. This is no more the case than imagination being unrealized reality! Translucency suggests. Translucency entices. Ideally, translucency engages and encourages intimate examination. Translucency soothes the senses and continues to fuel my artistic ambition.

the author Curtis Benzle received degrees from the Ohio State University and Northern Illinois University, and apprenticed in pottery with Robert Eckels. He is professor emeritus at the Columbus College of Art and Design (Columbus, Ohio). His work is in collections including the Metropolitan Museum of Art, New York City; Smithsonian, Washington DC; Los Angeles County Museum of Art, Montreal Museum of Art and Seto (Japan) Cultural Center. Benzle is a member of the International Academy of Ceramics and a former Trustee of the American Craft Council, past Executive Director of Ohio Designer Craftsmen, served on the Board of the Craft Emergency Relief Fund (CERF) and is the past-president of the Alabama Visual Arts Network.