Barry, you're right about the thin blendeed fabrics. If your cotton/poly shirt is a thin fabric, no problem. If it gets soaked and you get cold, you can always change to a synthetic base layer, and the cotton/poly combination will dry fast. What's really scary is when people try to use heavy cotton for insulation, such as heavy sweatshirts or sweatpants or bluejeans. That can be a sure ticket to hypothermia.

My daughter absolutely insisted on wearing bluejeans for her first backpacking trip. You know, the teenager (13) insisting on a fashion statement! The trail went through waist-high grass, which was sopping wet, and after two hours she was on the verge of hypothermia (of course she didn't say anything, but fortunately I realized what was going on). I got the tent up really fast, got her soggy jeans off, bundled her in her sleeping bag (with my bag as a quilt on top) and pumped her full of hot cocoa. She wasn't quite to the stage where I needed to crawl in with her, but it was close! After that trip, she was quite willing to go to the local military surplus store for a pair of Air Force tropical weight pants (50/50 polyester/wool). That was in the mid 1980's, and I still have mine. The fabric wears like cast iron! I don't know if such bargains are still available, but they are worth investigating.

On the other hand, in the late 1940's and the 1950's, cotton and very itchy wool was about all we had. I spent hours each evening drying my jeans in front of the campfire.

I am extremely grateful for the breathable and wicking synthetics that are available now!