"This really is a burgeoning trend, and clients are requesting more 'moments' of glass block in their space," Russell said.
Her clients now see glass block as a "luxury" material - though the long-lasting, low-maintenance, high-thermal-resistance material is actually cost-effective for homeowners seeking lower utility bills.
Glass block has cycled in and out of fashion before, said architect Jeff Krieger, owner of Krieger + Associates Architects Inc. in Chestnut Hill.
"It was fairly popular in the 1920s and '30s, and then again in the '70s and '80s," powered in part by Pittsburgh Corning Corp., the sole U.S. manufacturer of glass block, he said. "Usage declined through the '90s, but we've seen a little bit of renewal recently, as more people remodel midcentury houses."
Mary Lynn Bruce, market product manager for Pittsburgh Corning, hasn't seen an increase in glass block demand nationally - there are still so many parts of the country with a sluggish home market - but she has witnessed a need for the material in many historic renovation projects. The company is producing custom-designed block to match the material installed in the '40s.
"It's a material that lasts a long time," she said.
Krieger, for one, has had the opportunity to experiment with the translucent bricks in a couple of recent projects - and he's embraced it.
In a Mount Airy home that dated back to the 1930s, his challenge was to build an addition incorporating an existing stone wall that ran through the garden. He decided to cap the rustic stone half-wall, with glass block running the rest of the way to the ceiling. He liked the juxtaposition, he said: The blocks were substantial enough to hold their own against the stone, but also contrasted with its heft and poured sunlight into the room.
When working with an 1860s Center City townhouse, Krieger took on the material again. A glass-block-studded brick wall from a 1950s addition was already a striking focal point, so he decided to play off the theme - and take advantage of more recent technology. The glass-accented wall "was such an unusual piece," he said. "We thought it was worth preserving." He echoed the design in a new wall around the back patio, punching out holes and filling them with sustainably produced colored resin panels from the manufacturer 3form. The holes now double as niches for candles, which at night illuminate the panels with a jewellike glow.
Playing off glass block left over from the material's heyday is one thing; it's still unusual to see a contemporary architect double down on glass block for new residential construction.
But that's just what Old City's Moto Design Shop did in a Fishtown project that became a study in glass block and how to deploy it. The result: a striking modern rowhouse whose facade features a multistory bay window made up of the translucent cubes.
During the day, its reflective surfaces catch the color of the sky; at night, when the lights are on, it glows from within.
"It was a way of pushing the boundaries of what a traditional rowhouse can afford in terms of natural light," said Moto's Roman Torres. It achieved that, pouring gallons of sunlight inward while preserving the homeowners' privacy and providing sufficient insulation so that all that sun didn't overheat the house on bright afternoons.
The project did present engineering challenges because glass block isn't load-bearing, but the firm solved that by breaking the facade up into modules, each framed in structural steel.
Russell used glass block to build dividers within a recent addition, where the client wanted an open, sunny ambience to permeate a new bedroom and bathroom. She's also used it to build walls for custom, walk-in showers.
"Bathrooms are the most common areas where we install and design with glass block," she said.
A glass-block shower might be priced at about $2,500, which would include materials, design, and installation, even customized touches like built-in LED lights. Custom shower glass alone would cost about $2,000.
Russell says she likes the way both artificial and natural light interplay with the glass over the course of the day, and she, like Krieger, has found inspiration in the slew of new patterns, colors and textures on the market.
She's now a little surprised to find herself using words like elegant and edgy in the same sentence as glass block.
"It's strange, because I remember hating glass block before I became a professional designer," Russell said. "I remember seeing it in my elementary school and other commercial structures, and thinking that it was more or less the cheaper way to provide windows. It always felt somewhat like what I call 'grungy fenestration.' ... Now, glass block is really becoming the height of chic design in certain interior spaces. It has finally become an exciting material to work with."