Tucked away in the bowels of the Brooklyn Army Terminal is a 4,000-square-foot warehouse filled from wall to wall and floor to ceiling with garbage bags. They contain castoffs from New York’s fashion studios: mock-up pockets ripped from sample jeans, swatches in next season’s paisley print.

There is denim here in every wash, spandex in every hue. Dig through one bag and it is possible to find a little rug of carmine-colored fur and yards of gray pinstripe wool suiting. In another, embroidered patches from GapKids and spools of ribbon in velvet and lace.

Nearly 6,000 pounds of textile scraps arrive each week to be inspected, sorted and recycled by five staffers and many more volunteers at FabScrap, the nonprofit behind this operation. Since 2016, it has helped New York’s fashion studios recycle their design-room discards — the mutilated garments, dead-stock rolls and swatches that designers use to pick materials and assess prototypes.

So far, the organization has collected close to half a million pounds of fabric from the design studios of large retailers like Express, J. Crew and Marc Jacobs and independent clothiers in New York, New Jersey and Connecticut. Their discards have been shredded and recycled into stuffing and insulation or resold to fashion students, educators and artists.

“So much waste gets created in the design process,” said Jessica Schreiber, the executive director of FabScrap. “But it’s the tip of the iceberg.”

As climate change has accelerated, corporations of all kinds have become increasingly preoccupied with their sustainability cred. Four-fifths of consumers feel strongly that companies should implement programs to improve the environment, according to a recent Nielsen study.

Clothing companies in particular have faced pressure to change, from politicians, protesters at fashion shows and shoppers of all ages who want to reduce their carbon footprints. The fashion industry is often erroneously cited as the second-most polluting business in the world, but overproduction, chemical use, carbon emissions and waste are certainly issues it contends with.

Ms. Schreiber understood early the angst that waste was causing designers. In 2014, she was overseeing the Department of Sanitation’s refashionNYC program, which collects old clothing and textiles at farmers’ markets and in participating apartment buildings.

She received a string of similar calls from brands including J. Crew, Eileen Fisher, Express, Mara Hoffman and Marc Jacobs. The companies were sitting on piles of seasonal prints and swatches that couldn’t be donated but shouldn’t be thrown out.

“It really hit a nerve with people,” Ms. Schreiber said. Half of the designers had resorted to hoarding scraps under their desks as they tried — and failed — to find places to give them away. “There was a lot of guilt,” she said, and no clear path.

Spinning a Sustainable Yarn

For a designer, cutting down on waste isn’t as simple as recycling a few bags of fabric every week. It requires overhauling the brand’s business model: forgoing seasonal collections; eschewing — or being rejected by — traditional retailers that accept only large orders and standard packaging; selling directly to consumers; and getting design teams to think about the sustainability and supply chain of each material and garment.

Dana Davis, the vice president of sustainability at Mara Hoffman and an early FabScrap adopter, remembered feeling anxious about how the company could better deal with waste. “It just felt burdensome,” she said. But after a conversation with Ms. Hoffman, the designer, it became clear to them that change was necessary.

The company began shipping swimwear in compostable bags and made long-term commitments to the materials it purchased. To cut excess inventory, the brand moved away from the fashion cycle and the industry norm of placing orders on projection.

There are still challenges — like making sure consumers and retailers actually compost the bags — but other brands are getting on board with changes at the design, manufacturing and distributional levels.

It’s hard to pinpoint how much waste is created before a garment even reaches the consumer. Factory waste is not tracked by outside agencies. Supply chains are now so complex and reliant on remote contractors and subcontractors that the companies can’t account for all the materials.

Even if a brand wanted to find out how much fabric waste it created, “it would be very difficult for them to research that, because different factories might have different processes,” said Timo Rinassen, an assistant professor of sustainability at Parsons School of Design.

Wendy Waugh, the senior vice president of sustainability at Theory and a FabScrap client, knew that determining the brand’s total waste would be a challenge. The company works with many different fibers, which are sourced from all over the world. The company’s “Good Wool,” for instances, comes from a farm in Tasmania, and is scoured, spun and dyed at a mill in Italy before it is warehoused and sold around the world.

After a fiber is harvested and spun, it is sent to a factory where it is cut, dyed and trimmed. Reverse Resources, a software company that works with major apparel factories in Bangladesh and Sri Lanka, found that 20 percent of the fabric used in the cut-make-trim phase is ultimately thrown out.

Linda Greer, the founder of the Clean by Design program and a former toxicologist at the N.R.D.C., has advised many garment and dyeing factories in China. She said that brands frequently reject fabrics because they don’t match the desired shade exactly.

“I’ve seen so many ‘weeping piles’ of miscolored fabric,” Ms. Greer said. “Sometimes they can touch it up. And sometimes they throw it away.”

Once a garment is complete, it can present another problem: excess inventory. In some cases those garments are incinerated, which prevents them from being resold at a discount, Mr. Rinassen said.

Last year, Burberry burned $37 million of clothing and cosmetics to maintain “brand value.” The previous year, H&M came under scrutiny after it was reported to have incinerated 60 tons of unsold merchandise.

Stephanie Benedetto founded Queen of Raw, an online marketplace for dead-stock fabrics and a FabScrap partner, after seeing how much manufactured material was sitting in warehouses ($120 billion worth, by her estimate). At that volume, she said, waste isn’t just environmentally irresponsible — it’s “a C.F.O. issue.”

Apparently, also, a marketing issue. Fashion companies have been quick to invest in environmentally friendly marketing. There have been capsule collections derived from natural fibers like orange pulp (Salvatore Ferragamo), pineapple leaves (H&M), grape skin (& Other Stories) and mushrooms (Stella McCartney), and a wide selection of recycled polyester made from fishing nets (Burberry) and beach-strewn plastic bottles (Adidas).

These usually amount to little more than P.R. gambits and short-term fixes.

Samantha MacBride, an assistant professor at Baruch College and a former waste management professional, said that the ideas big brands implement often reflect a lack of understanding about waste management.

The way to minimize trash, she said, isn’t by devising a green marketing strategy or using new technological fixes. “The key is to produce less,” she said.

Sorting Through Scraps

Standing on the FabScrap floor, it is impossible not to feel overwhelmed by the enormous pile of trash.

Ms. Schreiber noted that the bags in the facility were “almost irrelevant in the scheme of what is probably generated.” None of the overstocked garments languishing in company warehouses are here. Nor are the huge quantities of fabric that are tossed from the factory floor.

Beneath the heap, seven volunteers slowly and manually sorted by material every scrap that came in. They inspected and removed labels and rubbed the fabric between their fingers. It could not have been further from the mechanized processes at a recycling plant, which employ feats of engineering — eddy currents, magnets and near-infrared scanners — to identify and categorize various types of metals, plastic and paper.

There is no technology in use that can detect the differences between, say, spandex and wool. “The infrastructure is lacking,” Ms. Schreiber said. “Like the fact that the sorting still all happens by hand is bonkers.”

The recycling processes are similarly decades behind. Today, there are a number of companies, like Evrnu and WornAgain, that are just beginning to recycle fibers, a process that involves shredding and dissolving the fibers into a pulp that can be respun into a new fabric.

Ms. Schreiber said that if clothing scraps were treated “as a waste-commodity stream, not a nonprofit-managed material, we would be further along in the tech.”

In the back corner of the warehouse is one of FabScrap’s two shops, where it sells many of the larger pieces its employees and volunteers find among the scraps. On any given day, some fashion students stop by, shopping and drawing inspiration from the ends of dead-stock rolls that are cheaper here than at fabric stores in the city.

Jasmine Velazquez, a fashion student at F.I.T., studied some green leather that she wanted to use for an upcoming assignment. “I’d rather buy leather from here than support the industry like that. Sustainability should be more important to me because I am a student,” she said.

In June, FabScrap opened a second shop, on a block in the garment district teeming with secondhand shops, and just a stone’s throw from F.I.T.

Camille Tagle, the director of reuse and partnership at FabScrap and a former evening wear designer at Pamella Roland, pointed out some of the special fabrics that filled the shelves. There were rolls of baby blue suede and white cotton with geometric fil coupé accents. Above the shelves were nearly full cones of thread in colors that evoked a Pantone guide.

“If it doesn’t match by a fraction of a shade, it’s out,” she said.

One piece in particular, a shawl’s length of pink crinkle chiffon with sequined flowers, caught her eye. Each flower had at least three or four colors arranged in a different pattern. “It takes a lot of time,” Ms. Tagle said. “A designer had to communicate all of those details to the mill.”

A steady traffic of students and hobbyists came in to peruse the shelves and scour the scrap bins. Olivia Koval, who is pursuing an M.F.A. in textiles at Parsons, left the shop with a tote bag full of mutilated jeans and denim scraps. She planned to overdye and felt them together to make a larger fabric.

“For people to feel inspired by something that was headed for the trash is really important for me,” Ms. Tagle said.

Since opening six months ago, the Chelsea store has served 4,800 customers. Next year, FabScrap plans to set up operations on the West Coast.

In spite of what she has built, Ms. Schreiber is measured about FabScrap’s success. “This is such a small group of self-selecting companies, and this is a very niche part of their waste stream,” she said. “That’s what’s so frustrating.”