Sergio Martins, a master tailor at Boyds for 16 years, has massive amounts of it.

After all, a tailor's work is never done, and he's at the top of his game. About 90 percent of Boyds' clients for men's suits are fitted by Martins.

Tailoring, he explains, is an art form that can't be measured in the number of suits or dresses sold.

"It's an inner feeling," he said, "that you've done your best work, and a customer is going to look his best. You just know."

But his craft is dying, and others like Martins, 56, who spent years, if not decades, honing their craft in their native countries and taking it to the United States are disappearing.

There were as many as 65 tailors at Boyds in the late 1970s and early '80s. Today, there are 30.

"There's not many of us left," Martins said.

Martins is the antithesis to "fast fashion" - the retail industry's buzzword for high-volume apparel, typically made overseas by cheap labor.

Primark, of Dublin, Ireland, comes to mind. The fast-fashion retailer is on fire and recently moved into King of Prussia Mall. It sells a suit for as little as $70 and moves a million pairs of socks a day globally, thanks to 700 manufacturers in 36 countries.

Boyds, by contrast, lives in slow motion. It has the largest tailor shop among independent retail specialty stores in the United States, according to MR Magazine, which tracks the menswear industry.

On a recent Friday, Martins spent 11/2 hours adjusting the side seam of a $2,000 Scuderi cashmere jacket. He also spent much of the same day on a suit jacket that needed the collar lowered and seam centered, between fitting several customers for new suits.

He's why tailors are the heart and soul of Boyds, at 1818 Chestnut St. After a Nov. 30 fire gutted the luxury retailer's famed fifth-floor tailor shop, co-owner Jeff Glass vowed to rebuild it bigger and grander than before. Crews began the task last week.

"We're all about customization," Glass said in his makeshift office on the fourth floor, near space where the tailors were moved, which used to be the shop's big and tall section.

Glass said that after the fire, the running joke was that regular customers first asked about the shop's resident rock star, Martins, and whether he was OK. Then they'd ask about the building.

"He's fantastic," said Matthew Steinberg, 37, an assistant professor at the Graduate School of Education at the University of Pennsylvania, who was fitted for a black suit by Martins a month ago. "He's very responsive to what I want."

Steinberg arrived at Boyds on a recent Friday, just before snow began to fall, to pick up his suit. He tried it on one last time in front of a mirror for Martins, who gave his nod of approval.

As closing time of 6 p.m. neared, Martins tidied up his work station on the second floor that sits next to - what else? - fitting rooms. On his desk were his tools: a sewing machine, thimble, ruler, chalk, "a horse," or mini-ironing board, scissors, rolls of thread, a pair of glasses, and razor blades. A tape measure was draped around his neck.

Fast fashion isn't the only threat to Martins' craft. Another headwind is that just about every neighborhood dry cleaner these days offers "alterations."

Then, there's the generation gap. Young folks, he said, aren't taking up the trade in his native Portugal, as they did in the 1950s through 1970s, when tailoring was most popular.

That explains why 40 percent, or 12 of the 30 tailors at Boyds, hail from Portugal - the most of any country. There are three each from Italy, the Dominican Republic, and the United States.

"This takes time to learn," said Martins, who started when he was 13, making buttonholes. He joined Boyds in 1999. "You need to have patience, and the younger people want to do something else."

Martins can relate. His brother and sister were trained by their tailor parents just as he was, but neither now works in the profession.

While competitive forces are nipping at their cuffs, the tailors at Boyds pursue work quietly.

Only the low, soothing sound of music coming from a radio could be heard, as the fourth floor hummed with activity on a recent Friday.

Maria Melo, 59, a tailor and fitter from Portugal, sat in one corner. The devout Catholic had a photo of St. Pio of Pietrelcina - the Italian Franciscan priest - taped to her sewing machine, and a small figurine of Our Lady of Fatima, Portugal, perched on top.

Melo, who lives in Northeast Philadelphia, worked with the precision of a surgeon - marking trims with chalk on a pair of pants that were to be shortened.

"To make a clean job, I open up everything," she said, as she began removing the seam with a razor blade to take in the waist and crotch.

With a Portuguese accent, she said there was a sure way to spot a "true tailor."

It's one who "uses a thimble to protect the fingers. Like this," she said, giving a quick sewing demonstration.

Across the room, Italian Enrico Porcha, 69, a master tailor and fitter, was laboring on a $1,995 navy blue suit jacket that needed the collar lowered and sleeves shortened. Jackets and top coats are his favorites, because "they are for big events."

Porcha, who was trained in Italy, admitted that the more expensive the clothing, the bigger the challenge.

"You don't want to mess it up," he said. "The customer paid a lot of money for it. It has to be perfect."

A presser or finisher can make $30,000 to $40,000, with benefits, at Boyds; tailors can make $40,000 to $70,000; and master tailors and fitters, $70,000 to $100,000.

"They are going to make a lot of money because there's not a lot of them," Glass said of the dearth.

But the demand for them is also being limited by machinery that makes tailoring more efficient - such as the shop's $17,000 buttonhole machine, which does the work of eight tailors a day.

Glass' grandparents emigrated from Russia. He said he sees their drive in his tailors, and that's why he is investing more than $1 million to rebuild the fifth-floor tailor shop - to pay homage to their craft.

"It's what this country was built on and has to be preserved," Glass said. "People are not machines."