THE STUDIO WHERE THEY BRING STAINED-GLASS WINDOWS BACK TO LIFE IS AS QUIET AS A CHURCH. The fluorescent lights hum, but there is little talk. Most workers listen to the radio through headphones. Most of the tools are quiet, like the soldering irons that silently fuse the windows' lead joints.  The occasional conversations at Serpentino Stained & Leaded Glass Inc. in Needham wouldn't seem out of place in a library -- workers consulting colleagues on a difficult problem.


"We all help each other, because we all care about the art. That's very important. Nobody does this because they want to have a job . . . but because they love it," said Domenico Iriti of Needham, a partner in the business.


Joseph Serpentino, now 89, a native of Italy, founded the business in Needham in 1968. He made stained-glass windows and repaired them. Nowadays, the company concentrates on restoring them.


Serpentino's daughter, Maria, began running the business in 1976 while she was a student at Babson College. Her father retired in 1983.


In 1982, the company constructed a commercial building on Highland Circle, a small dead-end street off Highland Avenue in Needham near the Charles River. The building includes a 4,200-square-foot studio and a chimney for the kiln. Ten people are employed there, each a skilled worker.


A window begins with a piece of glass, either clear or colored. An artist paints an image on the piece, which is then fired in a kiln so the paint is sealed. The panes of glass are held together in the window by strips of lead.


Stained-glass windows are made to last -- artists and restorers tend to speak in terms of centuries -- but problems inevitably develop over time.


Portions of a window can deflect, a term used in the business meaning to bow, bend, or buckle, if the leading doesn't provide sufficient support or if heat builds up in an area that isn't properly vented. As glass expands because of temperature, the lead expands with it, but as glass contracts, the lead does not, which can leave gaps between the glass and the leading. Lead also eventually deteriorates.Ultimately, a piece of glass may crack or fall out. Stained glass can also get dirty. In some instances, the owners of the windows paint over them, ruining the intended effect.


Restorers remove the windows intact and bring them back to the studio. They document the windows with photographs and rubbings made on acid-free vellum with a rubbing stone (made of wax and crayon) or carbon paper.


The rubbing provides a sort of full-scale map of the window. Information is also recorded on the width and types of lead.


Then the windows are disassembled, and each piece of glass is cleaned. Cracked pieces are glued together using silicone, epoxy, or copper foil. The panes are put together again with leading -- using new lead, if necessary, or the original lead if possible.


The shop smells of linseed oil from the putty that is used on the leading to waterproof the windows and make them more rigid.


The painstaking process of restoring the windows takes months. At any one time, the company is working on six to eight projects.


It is currently working on a restoration project for Trinity Church in Boston, along with John Canning Painting and Conservation Studios of Cheshire, Conn., and Cummings Studios of North Adams.


Arthur Femenella, a stained-glass consultant and conservator who often refers projects to Serpentino, said that while there are probably a few hundred companies in the United States that work with stained glass, there are fewer than 20 that do the sort of high-quality restoration work Serpentino does.


"They're a very good studio," said Femenella, president of Femenella & Associates, of Annandale, N.J., who worked with Serpentino on a chapel at Princeton University, among other projects. "They're one of the few studios that is constantly trying to improve their work."


The company's past projects include the Hall of Flags at the Massachusetts State House in Boston. Between 1999 and 2002, Serpentino also restored many stained-glass windows at the Christian Science Plaza in Boston, including those in the Mother Church, the Mother Church extension, and the Mapparium.


"We were very pleased with their work. Their work was careful and thorough," said Alan Spence, capital project manager at The First Church of Christ, Scientist.


Iriti, originally from Bova Marina in the Calabria region of southern Italy, came to this country in 1982 and soon got hooked on the stained-glass business. He calls it "love at first sight."


Roberto Rosa was born in New York but spent much of his childhood on a farm in Sora, Italy, about an hour's drive east of Rome. He attended art school part time in Italy before returning to the United States in the mid-1980s.


To this day, Rosa finds it hard to stay away from the studio. For him, there are no dreaded Mondays."I just can't wait to go to work", he said.


Rosa was and remains attracted by the chance to combine art with artisanship.


"I just loved the fact that you're not only working with an art form, but it's also working with your hands, being a good craftsman," Rosa said.


Windows the company has restored include works by some of the greatest stained-glass artists, including John LaFarge (1835-1910) and Louis Comfort Tiffany (1848-1933).


Tom Barber, a Belmont resident who worked as a musician and in television before going into stained glass full-time about 18 years ago, pointed out that although some stained-glass pieces are great art, many are in inaccessible places, such as near the ceiling of a church. He gets to see them up close.


"You've got a piece of glass in your hands that you're the first person to see in 100 years or more," he said