85% is awfully high wool content. Smartwools , which are pretty much the gold standard nowadays, are only about 70%. Hit the specs button on the link.

To get 85%, you pretty much have to go with ragg wool, which is abominable compared to the much more comfortable and much better wicking merino wool socks available. Ask him to rethink the 85% requirement.

Or else, just bring smartwools, because he probably doesn't realize how much nylon is in a high-grade "merino" sock.

BTW, I am comfortable in my merino socks until it hits at least the 80's.