Here’s the skinny: tech fabrics don’t make the grade. I’ve tried a bunch of them over the years and I always come back to my 100% cotton shirts. Cotton is cooler, that’s all there is to it. And I’m not alone. Several friends say the same thing.

Fishing shirts and pants made out of the tech fabric look really cool. I’m sure that’s why all the fishing guides have adopted this stuff as their virtual uniform. And I’m not questioning the textile engineers who design tech fabrics. I’m sure the technical fabrics really do wick away perspiration. But based on a simple experiment I did some time back, that’s precisely what makes technical fabric shirts so stifling and uncomfortable.

You can try the same experiment I did. Take two shirts of similar construction—tees, polos, short-sleeve or long-sleeve, you choose—that are made of different fabrics, one the polyester wicking stuff, the other 100% cotton. Dampen each shirt FROM THE INSIDE with one a spray bottle of water until you can see that it is damp, but don’t get it soaking wet. You’re simulating perspiration. Put each shirt on in turn and stand in front of a fairly powerful fan to simulate a breeze on the water. Tell me which shirt is cooler. If you’re like me, it will be the cotton shirt.

Here’s my theory of how it works. Cotton soaks up moisture and holds it. The moisture on the inside stays in contact with your skin. The moisture on the outside evaporates. Recall from high school physics that as water evaporates it cools. Recall also that water is a great conductor of heat (or cool, as the case may be). That cooler water on the outside of the shirt also cools the moisture next to your skin, thus cooling your skin. But what happens if the moisture is wicked AWAY from your skin? The water on the outside of the shirt is evaporating and getting cooler, but there isn’t any way for it to in turn cool the fabric next to your skin since there’s no moisture there. That’s why you feel warm and clammy in a tech shirt and cool, albeit a little damp, in a cotton shirt.

I know this is heresy to all the fishing guides whose uniforms consist of tech fabrics out the wazoo. Fine, if you think you have to look cool, then go ahead and suffer. When I’m fishing I don’t care what I look like, as long as I catch fish and stay cool doing it. There’s “cool,” then there’s cool.