Good glassblowers are patient and skilled, cautious and responsible. But above all, they need extensive experience in their trade, since handling fragile glass tubes is a delicate matter. A moment of distraction is enough to destroy hours of work. In the Czech town of Bruntál, Lucie Kunovská makes high-quality bulbs for HBO lamps – and as an extremely talented newcomer at that.
“Everything has to be exactly right down to a tenth of a millimeter and absolutely clean.”
Glassblower in Bruntál, Czech Republic
Because it is hard to find quartz glassblowers in the Czech Republic, OSRAM looked to its own staff at the Bruntál plant to train them for the production of HBO and HMI bulbs. Lucie, who has been with OSRAM since 2007, has proven to be particularly skilled. “After just a little over a year, Lucie is already delivering excellent results,” says production manager Jaroslav Furiš. “Although the regular training takes up to three years.”
Bruntál produces bulbs for high-pressure mercury lamps with an output of 1 KW to 25 KW. They are used in the entertainment sector and at sporting events, as high-output daylight sources in the film industry or in the production of LCD screens. In an eight-hour shift, Lucie manages seven bulbs. Very experienced colleagues produce 10 to 15 bulbs per shift.
In order to form a bulb for a gas discharge lamp, Lucie starts by aligning up to five short glass tubes along an axis. Using a burner, she melts them to form a single long tube. “There must not be any seams visible, and the glass may not contain any contaminants or enclosed bubbles,” Lucie says. She hangs the glass tube into a machine. Using graphite, she carefully inflates the center of the tube while operating a foot pedal to control a hydrogen flame that is over 2,000 degrees hot.
A shield protects Lucie from the flame, and a darkly tinted viewing panel fends off UV light and prevents eye injury. Still, it remains a hot job – especially since she has colleagues working beside her at nine other machines. “I don’t really mind the heat,” Lucie says. “I don’t sweat that easily.”
Once the quartz glass has been blown into the desired size and has cooled off, Lucie checks the quality of the bulb once more using a special measuring device. Everything has to be exactly right down to a tenth of a millimeter. The glass has to be stable, clean and non-glare,” Lucie says.
“I really enjoy glassblowing,” Lucie says. “But it’s not easy. Luckily, my more experienced colleagues are there to help me. That way, I learn something new every day. I hope I’ll have the 2.5 KW bulbs down soon, since my goal is the big 25 KW bulbs, of course!”