+2 -- Our skin react differently to different fabrics. I don't find my 80/20 poly/cotton blend any hotter or less comfy than cotton in any way -- so I enjoy the benefits of blended fabric without the cost.

OTOH, even after tons of literature attesting to the seemingly endless advantages of merino wool -- I just can't get over the itch -- a low level but ever present itch just enough to be annoying.

"OTOH, even after tons of literature attesting to the seemingly endless advantages of merino wool -- I just can't get over the itch -- a low level but ever present itch just enough to be annoying."

Ben, have you tried the BPL merino. I've been like you all my life, incessant itch from wool (kinda embarrassing where I live), but found the BPL merino (I originally got it for my son but he never got it :0) to be itch free. Still, a clingy long sleeve black knit is not something I would chose to wear on a hot summer's day!

I hate polycotton blends!!

I do a lot of my hiking in central Florida where I live. Summer here is very hot and humid. Temperatures are hovering from mid 90's to mid 100's (F) this summer and with the high humidity, it feels much hotter than that. I've tried just about every fabric you can think of while hiking in this heat, and haven't noticed much of a difference. When it gets that hot, it's really hard for any fabric, natural or synthetic, to perform well. Nowadays, I will just hike with no shirt and some light shorts. Otherwise, the shirt I'm wearing will be stained white from the salt in my sweat after it dries. I'll usually have a long sleeve synthetic with me to wear after I set up camp to help with the bugs.

Now if you live somewhere where there is a chance temperatures could suddenly drop, I would go with synthetic. But in Florida, I don't have to worry about that.

-Sid

Don't forget about fabric weave/construction. A regular cotton T-shirt will restrict cooling and drying air movement more than a meshy type of nylon shirt. Ok, not "mesh," but I think you know what I mean.

My Champion C9 shirt is MUCH cooler than a cotton shirt, and dries quicker.

"Nowadays, I will just hike with no shirt "

I used to do this, but I just could no longer put up with the woman pointing and laughing, and the terrified look in children's eyes as they clung to their mothers' legs.....

Douglas- you made me laugh out loud and scare innocent standers-by!

Cotton prices soar after India bans export sale of the fiber

http://www.washingtonpost.com/business/cotton-prices-soar-after-india-bans-export-sale-of-the-fiber-other-commodities-are-mixed/2012/03/05/gIQAarkDtR_story.html

As if we needed more supporting information to move away from Cotton...

In the summer, where it's hot ALL DAY LONG... I am not talking about being in the mountains. I am talking about where it hits 90's and stays the same temperature until night, I don't see why cotton wouldn't be fine.
Cotton just sucks the most when it's something like 60 degrees and you get hot and sweaty while hiking, and then you get to the top of a ridge or mountain and stop for lunch and the wind starts blowing. It's more annoying that dangerous.