It started with a garden cushion and a sandwich press.

In the early 1970s, three Seattle engineers and backpacking buddies were kicking around ideas to start a new company. Two had been recently laid off during the Boeing Bust while the other still worked for the Lazy B. They all had a common gripe: Sleeping in the backcountry was the pits.

In that era, a night out under the stars was cushioned, at best, by closed-cell foam sleeping pads or even pool floats. Those unwilling to pack such unwieldy creature comforts — closed-cell foam doesn’t compress much — made do with the ground.

The eureka moment struck when one of the unemployed engineers, Jim Lea, was gardening. As he leaned on a knee cushion, he noticed that the open-cell foam he compressed with his body weight released air then eventually puffed back up. Talking it over with Neil Anderson, the other unemployed engineer, the pair hypothesized that if open-cell foam could be encapsulated in airtight material, a valve could control the internal air pressure. One could compress the mattress into something packable, and have it self-inflate into a thermally insulated sleeping pad.

Anderson, Lea and John Burroughs, still employed at Boeing, created prototypes, using a sandwich press to wrap fabric around the foam pad. Burroughs coined the name “Therm-a-Rest.” The three patented the design in 1972 and went on to found Cascade Designs, the Seattle-based company that still makes most Therm-a-Rest products at its Sodo factory.

The homegrown invention, which celebrates its half-century this year, is now a worldwide staple that cushions the sleep for millions of campers. and Burroughs still serves on the board of Cascade Designs.

But even as the company and its marquee product have grown, Therm-a-Rest has largely kept its manufacturing in-house despite the trend for U.S. companies to send industrial production overseas. Between the engineering talent that courses through Seattle and the city’s proximity to ideal field testing grounds in the Cascades, Therm-a-Rest retains its local roots.

The rationale is simple, explained project manager Brandon Bowers on a factory tour in August.

“This unique equipment is your best place to prototype new ideas as well as monitor your current quality,” he said. “For the last 50 years, we’ve been taking those ideas and improving how to build them.”

Cascade Designs is spread between two squat Sodo warehouses totaling 110,000 square feet. The Yosemite building is home to administrative offices where a desktop pair of snowshoes isn’t a strange sight. But the magic happens across the shared loading dock in the Chamonix building: Machines whir and hum, factory workers press and cut, raw foam comes in, finished pads go out.

Bowers, who managed the Therm-a-Rest product line for nearly 17 years, can wax poetic about foam.

“Foam is like a huge loaf of bread,” he said, gesturing at a 200-pound hunk of squishy polyurethane, which Cascade Designs sources from suppliers in Kent or Vancouver, Washington.

Vertical integration in design and manufacturing is one of the company’s strengths, but Cascade Designs still depends on raw materials from elsewhere, and has had to substitute materials or delay product delivery in these recent, COVID-19-hampered years. “Supply chain issues have been equally painful for Therm-a-Rest as they have been for the rest of the world,” company spokesperson Karen Lamerick said via email.

Once a machine known as a computer numeric control cutter starts slicing into the foam, Bowers shifts metaphors. “Foam is like wood,” he said, noting that it can have different grains and that not every piece is uniform.

“This is still a complicated bugger to make, even though it only has five components,” he said.

On one side of the factory, an assembly line cranks out the Trail Scout, a classic entry-level model. The machine in charge of the main event — encasing a foam pad in fabric — still looks like a sandwich press, just human-size and heated to 330 degrees Fahrenheit. The factory can produce 350-400 Trail Scouts per day, feeding a product line that sells 30,000-40,000 units per year.

With the boom in outdoor recreation sparked by the pandemic, Therm-a-Rest saw double-digit growth over the last two years, though the sales curve is leveling out.

“Those who started camping during the pandemic will continue to, and hopefully progress in their new enjoyment of the outdoors,” Lamerick said.

Cascade Designs navigated the pandemic with minimal changes to its factory floor, as the physical configuration of the work already requires spacing, and has since resumed pre-pandemic operations. The company still requires proof of vaccination for new employees and employees who test positive for the coronavirus must notify their supervisor.

Across the factory from the Trail Scout station, a contraption churns out the MondoKing 3D, a plush mattress that would satisfy even the titular character of “The Princess and the Pea.” Demand is strong for car camping comfort — Therm-a-Rest makes thousands per year and is still frequently out of stock.

“This little machine is unique to the world,” Bowers said. “If we needed another one, we’d have to build it.”

Tucked away in a back corner of Chamonix is Therm-a-Rest’s top secret operation.

“Foam is where we started and it’s still the most comfortable product you can sleep on,” Bowers said. “But around 2005, we started researching air pads for lightweight compactness.”

With growing interest in light and fast modes of backcountry travel like fastpacking, Therm-a-Rest introduced the NeoAir line — from the regular XLite, which balances warmth with weight, to the UberLite, which packs down to the size of a beer can and weighs just 8.8 ounces.

The NeoAir line has devoted followers among hardcore backcountry travelers. Dandelion Diluvio-Scott, an ultrarunning and trail running coach for Team RunRun who trains in the Cascades and Wyoming’s Wind River Range, swears by Therm-a-Rest for winter camping.

“I travel and camp in the backcountry year round and this includes overnights when the temperature dips to -20ºF,” she wrote via email. “In winter conditions it is critical to have a warm and reliable ground insulation system and the NeoAir XTherm MAX sleeping pad is my go-to choice when the mercury drops.”

No sandwich presses are involved in the NeoAir line: The manufacturing is all automated laser cutting controlled by a programmable digital interface.

Per Bowers, it’s “the most complicated and cutting-edge technology for air mattresses.”

No photos are allowed of the five machines, each of which costs six figures; the sleeping pad business has gotten competitive in the last 50 years, with Swiss brand Exped, Steamboat Springs, Colorado-based Big Agnes, Australian brand Sea to Summit, and New Hampshire-based Nemo all looking for a slice of the pie. Demand is so strong that Cascade Designs is adding two machines.

There’s no catalog for these bad boys, though. The machines making the NeoAir line are all built in-house by the company’s engineers. A metal label on the side of each machine states: “Manufactured by Cascade Designs.”

“We can’t get rid of the desire to innovate,” Bowers said.

Bowers joined Cascade Designs in 1998, fresh out of engineering school at the University of Washington. He liked camping and “didn’t want to work for Boeing.”

The UW, as well as Western Washington University, remain strong feeders into Cascade Designs. Other employees transfer from more conventional industry jobs.

“The No. 1 reason people are here for engineering is their passion for the outdoors,” Bowers said. “There’s a cachet working for an outdoor company.”

There’s also the appeal of conducting laboratory research under the same roof as the product’s designers and manufacturers.

Over on the assembly line, there are several old hands. Congenial working conditions seem to breed longevity: Cascade Designs boasts 28 assembly line workers, known as “production specialists,” who have worked there more than 25 years. (The starting hourly wage is $15.75.)

On the day of our August tour, the repair shop was busy, too, packed with punctured air mattresses. On a good day, the team repairs about 50 pads, which hang to dry after being submerged in a 230-gallon dunk tank to test for leaks.

“Punctures happen all the time,” said repair technician Liam Eagan. “And when there are valve or seam issues, that could be a manufacturing defect.”

Using adhesive cured by ultraviolet light, Cascade Designs commits to repairing any Therm-a-Rest product with fewer than 10 punctures. The company espouses a repair-first philosophy to keep products in the field as long as possible. Customers can even buy field-repair kits and it’s not uncommon for the repair shop to receive decades-old sleeping pads.

The repair shop is just a short stroll from both the factory floor and designers’ desks, allowing technicians to provide feedback if they notice recurring manufacturing defects.

That tight-knit culture continues to serve Therm-a-Rest well, allowing for agile moves like resuscitating production of a 3-year-old product that proved unexpectedly popular.

“We couldn’t have done it had we not invested in our own equipment and been hyperlocal with our manufacturing,” Bowers said.

“That part of our company has stayed the same.”

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