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SITKA Team | Photos by Craig Francis & Matt McCormick | 1.18.2021

The Science Behind Nodak

Snow goose hunters know the best chance they have for a successful hunt in an open field is to disappear into it. For years they’ve relied on whites—including disposable painters suites or white PVC raingear—for concealment. Bulky, uncomfortable and non-breathable, these suits eventually fall apart or fail before the season’s over, ending up in a landfill before their time.

The performance and durability problems that are specific to snow goose hunting not only seemed solvable to us, it also felt like it was our responsibility to develop a best-in-class product that aligned with the ethics of hunters who don’t like to see anything go to waste. We needed to design something that offered concealment, comfort and long-lasting durability. Working directly with Gore enabled us to design something that’s not only built by waterfowl hunting experts, but based on advanced scientific knowledge of how birds see.

Jim Saubier, SITKA waterfowl Product Manager, teamed up with Gore engineers and vision experts to understand how birds see, specifically in regards to the UV light spectrum; the part of the spectrum the human eye can’t see.

The human eye has three cones that enable us to see three primary colors in the visible light spectrum. This happens within the range of 700 to 400 “nanometers” (measurements of wavelengths), from long wavelengths to short. If you think of a rainbow, from red (700) to violet (400), on the other side of violet—the part of the spectrum we can’t see—is the ultraviolet (UV) spectrum of light.

Scientists have known since the ‘70s that birds have a fourth cone in their eye and they see four primary colors: the three we see plus a fourth color in the UV spectrum. This fourth cone enables them to see the shorter UV wavelengths that range from 400-300 nanometers.

Gore Fabrics Application Engineer, Scot Tims, teamed up with Jim and vision experts to conduct research on the UV reflectance profile of the color white in order for snow goose hunters to not be seen as a threat. UV light is either absorbed or scatters from objects, with varying degrees of absorption and reflectivity depending on the material composition and surface structure of the object.

For example, you experience a high level of spectrally uniform reflectance from the ground when you’re in a snow field—which can reflect 90% of sunlight, including UV. Or you experience an overall lower level of reflectance when you look at a leafy canopy, which strongly reflects the color green and absorbs all of the other colors.

However, scientists theorize that a bird’s experience is somewhat different. Their ability to sense a fourth color in the UV range allows them to better discriminate the shape and orientation of objects. What to us looks like a purely white snowfield or a green canopy is different than what they see. Their environment has more contrasting features, which can aid them in navigating during flight and seeking food.

“Knowing the birds’ visual sensitivity to UV light,” says Scot, “we set out to develop a fabric that would be non-threatening to snow geese from a visual standpoint.”

Using a UV/visible spectrometer, the team first measured the reflectance of decoy paint—proven to be an effective snow-goose-hunting color—and a handful of snow goose feathers. The measurements showed that both materials had a significant reflectance level in the UV range that birds can see in, and specifically that snow geese identify as either more geese or snow patches.

Using decoy paint and snow goose feathers as benchmarks, they considered several fabric options until they found a white 3-layer Gore fabric to see if it reflected UV light at a similar level. The fabric reflectance measurement landed within both the wavelength range and level of both whites so they knew they nailed the color.

Then, because natural UV light can deteriorate the color white under long periods of exposure to sunlight—turning it more yellow over time and negatively affecting the UV reflectance profile—they subjected the Gore fabric to hours of simulated sunlight in an accelerated weathering chamber. The weathered fabric maintained its UV reflectance after the prolonged exposure. The team felt confident they had landed on a color that would offer the highest level of concealment performance of any whites on the market.

Since all of this testing took place in a lab, they needed to get prototypes out into the field. Aside from testing the color profile of the prototypes and getting positive feedback on the concealment performance, they also tested the durability and comfort of the bibs and jacket, putting them through days of real-life use in muddy, stubbled fields. The team paid special attention to common failure points like zippers that often succumb to mud and grit over time.

Being able to work directly with Gore, conduct original research and rigorously test our initial findings and prototypes—both in the lab and in the field—resulted in a groundbreaking whites system that has no equal.

“We’re really happy with the end result,” says Jim. “Game-changing non-disposable whites that are comfortable, dependable, and provide ultimate concealment in the field.”