With chromium as a coloring agent off the table, the art glass manufacturer has found another way to make green glass

DAVID F. ASHTON - Bullseye Glass Companys Sarah Milliron shows some of their new green glass, made with an ancient process not using chromium - including a sheet of double-rolled opalescent Citronelle. With one major art glass manufacturer closed in Portland and being moved to Mexico, and with east coast glass makers' use of hexavalent chromium remaining unregulated, Brooklyn-neighborhood-based Bullseye Glass Company, a renowned art-glass maker, seemed unable to produce green-colored glass.

Until now.

Instead of skirting Oregon Department of Environmental Quality (DEQ) regulations, the firm found a new and different way to make green-colored art glass.

"Even with the highest technological response through our air filtering system, we still can't use hexavalent chromium, or chrome, the primary colorant for green glass," said Bullseye co-owner Lani McGregor.

"Because we can't use this relatively 'new' element, our chemist started looking for a solution by researching glassmaking in the Middle Ages – to see how they made green glasses without chrome," McGregor told THE BEE.

"Our chemist has some very old books in his collection," reported company co-owner Dan Schwoerer, as he admired a sheet of Bullseye's new green glass.

Through trial and error, Bullseye workers tried ancient formulas – using approved manufacturing elements and processes – and found success.

"Although this has been a very challenging year, the exciting part is that we're coming up with a whole palette of new green glasses, exclusive with Bullseye," McGregor smiled.

"So, as far as we know, we're the first to offer truly 'green', green art glass," Schwoerer added.

Cleaning Portland's air

Schwoerer talked about the progress the company has made to filter the air coming from the plant's glass-melting furnaces as he led THE BEE on a tour of the facility in late January.

"When the DEA announced air quality 'benchmarks' for hexavalent chromium – which is .08 ng/m³ – the background level is higher than that," Schwoerer remarked "In order to meet that 'benchmark' level here, we'd have to take all of the air in the city, and clean it, to get it below that level!"

With the company's $1 million air filtration "baghouse" systems up and running, their next challenge, Schwoerer said, was adding and calibrating an exhaust air leak detection system to warn if any of the filters were leaking elements. "It's a pretty cool device that monitors the air, after it's been through the filtration system, but it's not cheap – it costs about $25,000 to install and program.

"And, although it's required by the DEQ, they told us that they don't know of anyone that actually has one of these monitoring systems installed, and they havn't yet provided monitoring and alarm-setting practices," Schwoerer added.

Standing under the baghouse units, Schwoerer pointed out the probe inserted into the post-filtering air stream which counts particles moving past it via what's called the 'triboelectric effect'. When particles hit the probe, they give off electrons, causing measurable current flow.

Technically, this monitor isn't finalized, because it has yet to undergo certified calibration. "It will be 'source tested' as it measures grains per cubic foot," Schwoerer said. "The permanent rule requires us to be below .005 grains per cubic foot – a very small amount, because there are 7,000 grains to a pound."

Just then, loud-but-muffled "booms" resonated in baghouse area when a worker set a control to "purge" some of the 72 HEPA filter units, with a blast of air inside the sealed unit, causing the collected dust to be blown off and drop down into a sealed collection system.

"We're really starting to feel confident that the system is working well and consistently, and we aren't getting any surprises. We're glad we've been able to accomplish making glass using an artesan process, but it hasn't been without a substantial cost," Schwoerer said. "Beyond the equipment investment, our managers haven't had time off in the last eleven months, as we install and learn to operate the new systems."

McGregor chimed in, "Some people say it's great that we're up and running again, as if it all happened overnight. But, we have been working for a solid year now, and continuing the effort for likely another six months or a year, to get this entire new system fully functional."

In the end, the result will be worth it, the couple agreed – to be able to keep operating their business in the Brooklyn neighborhood, employing local people, and supplying customers locally and around the world with art glass.