Hardcore Luxury®

Light Test

One of the ways people often estimate the density and wind resistance of a wool fabric is what is often called The Light Test.

Hold the wool between your eye and a light source, and see how much of the light comes thru.

A lot of people do this, and the test is somewhat instructive. But just lately something came up and I felt the need to add a page to the website to discuss.

A customer phoned to tell me he'd just received a new Lynx Pattern All-Around Jacket from us, and he was surprised by the results of his light test. He'd compared his new Lynx Pattern All-Around Jacket with some Drab WeatherWool he'd had for a while, and he was surprised that the new Lynx let significantly more light pass thru. This result also surprised me, and I'd previously seen the same thing.

I was surprised because we knew that the Lynx Pattern had the same weight as before, and it had also the same wind-resistance properties. So I didn't understand why it would allow more light to pass through. But I think I know the reason.

And this explanation is a little funny because it relies on people understanding the contextual differences in the way the words "light" and "dark" are used. There won't be a problem for people who are native speakers of English. But we have quite a few readers for whom English is a second language.

Compared to "dark" colors, "light" colors reflect more light waves. Our FullWeight Lynx Pattern and Black Fabrics are made from the same fiber, spun into Yarn with the same specs, and woven into Fabric with the same specs. But the light-testing our Black and Lynx Fabrics shows that Black Fabric will absorb far more light than will the Lynx.

Black is black because it absorbs all the different colors of light waves. That, I think, is actually the definition of black. Lynx has four different colors, all of which are lighter than black, and one of which is undyed, almost-white wool. Lynx is a lighter color because it reflects many different color light waves. And so when Black and Lynx are compared side-by-side in a light-absorption test, Black will absorb far more light than Lynx. This may lead people to conclude that the Black is a tighter weave, or that Black might stop more wind than Lynx. But it won't. I think the light test only tells you about light. Or maybe the light test is only indicative if you compare the same color.

The idea behind the light test is that the more fibers, the more light will be blocked. But I don't think "blocking" is all that is happening. Light colors reflect light waves. So I think the light waves bounce around within the light-colored fibers of light-colored fabric, and eventually find their way completely through the light color fabric ... not because they have encountered fewer fibers, but because the light fibers reflect the light waves and many light waves makes it all the way through the fiber. It is my guess that the light fabric looks light from the opposite side of the light source test is the same reason it looks light from the same side of the light source. Light colors reflect light waves.

With luck, somebody who reads this will understand better than me and help me clean this up ... or maybe tell me I'm all wrong!

23 February 2021 --- Ralph