FORLOH’S Product Designer explains how the company built the most advanced down jacket on the market

Puffy jackets these days are as common on the streets of New York as in the Rockies wilderness. The odd and astounding evolution of this hardworking piece of equipment to mere fashion gives the impression that every puffy is equal.

Nothing could be less true.

Whereas almost every other insulated jacket is built to simply capture warmth, FORLOH’s ThermoNeutral Down Jacket and Vest are finely honed equipment that harness the body’s heat while still allowing moisture to escape. That’s key, because being dry means being warm.

“We’ve run the numbers. This is an insulation mid-layer that’s more weather-resistant than most outerwear and more breathable than many brands’ base layers,” says James Mohan.

FORLOH reached these benchmarks by completely reinventing how an insulated jacket is built. In development, they discovered that the seams that create the baffles in a standard down jacket construction are the cause of major problems: Not only do the needle holes for the stitching allow rain and snow to penetrate the jacket, but the thread also soaks up the water, conducting moisture to the down and causing it to get soggy and lose its insulative properties.

To address this, the product development team nixed typical sewn-thread seams for sonic welding, which bonds the inner and outer layers of Ripstop nylon together using heat. The process not only gets rid of moisture-absorbing thread, but it also eliminates needle holes that would otherwise compromise a garment’s weather-resistance. At the same time, the heat process creates a porosity at the molecular level that allows moisture to escape. The result, called Perf-Weld, yields an insulating garment that’s impervious to moisture from the outside but still allows sweat on the inside to vent.

Sonic welding is not completely new to market, but FORLOH developed and honed the process to reap all the high-tech benefits. The company experimented with the thickness of the weld, eventually settling on 5 millimeters as the sweet spot between durability and porosity for moisture transfer. And when lab testing showed that the existing wheels for sealing each weld created too large of pores in the fabric, FORLOH engineered its own to perfectly control the moisture management.

The other key to ThermoNeutral is the insulation. Down gets its insulating properties from its loft, i.e. the trapped air and buffer space between the feathers. The problem is that standard down is highly susceptible to water, which causes the feathers to glom together and lose their loft—and thus the insulating properties. So FORLOH partnered with DOWNLITE, which produces duck-down insulation cured with a hydrophobic treatment to repel water. Compared with untreated feathers, Activ-dri™ Down reduces moisture absorption by up to 60 percent. And in the rare instance it gets completely saturated, it dries 33 percent faster than standard down. “The key to keeping warm is keeping dry,” says Mohan. “That can be tricky with down, but we sidestepped those issues with this technology.”

With the combination of PerfWeld and Activ-dri, FORLOH’s insulation system appreciably improves the hunting experience. Unlike on most hunts, where a transition from glassing to high-speed chase usually means lost time layering and removing apparel, with ThermoNeutral Down you can move immediately without the risk of soaking your gear. And though it is designed as a mid-layer in a three-layer system, it’s also practical as a top layer in dryer climates, especially for aerobic efforts. Mohan says that the 650-power fill that FORLOH chose contributes to the versatility. “We could have gone with a higher fill power, but given the aim to have the jacket work both solo in high-exertion situations as well as in the system, this hit the sweet spot,” he explains.

“When (FORLOH founder) Andy (Techmanski) came to me with the list of ideas and performance parameters for these garments, I was like, ‘Can we do this? Probably not. But we’ll try.’ What we accomplished surprised even me,” says Mohan. “This is the only down jacket I’ve ever worn that I’ve been able to go as hard as I want to in and not end up soaked.”