shemagh/bandanna for high altitude?

A bandanna works. The only trick is the fastening method. I generally use a large safety pin.

The issue is that you can get a terrible sunburn if you have to cross a high altitude snowfield on a sunny day. It is extra bad because the radiation is coming up from the ground direction, not straight down from the sky. So, you tend to get a sunburn on the underside of your chin, the roof of your mouth, and the underside of your nose. Any sort of cloth is useful in blocking that.

I've also used a white silk balaclava, although it is not as multipurpose as the bandanna. Just suppose the wind whips that off your head. Now what are you going to use?

–B.G.–

Silk bandana is my go to multi use item. You can get them in a 42"x42" that would be large enough to use as a shemagh, but not near as heavy as a traditional cotton one. I've hardly ever needed to rig it shemagh stile, but I do stick it under my hat to shade the back of my neck quite often.

Also use as a pot holder, towel, prefilter, etc.

A bandanna is the cheap/easy route. No free lunch on making things stuffy– you will be covering your face. A shemagh is usually made of loosely woven cotton, so it will breathe well and it will cover your whole head and face.

I like a Buff. It serves as scarf, face mask, full head cover with a ball cap.

Any thoughts on the sun blocking properties of a black mosquito head net?

I also like my buff, and was just using it as a balaclava last week on a 100-mile trip to keep the sun off my neck and face. Very light, kept me warm at night, and can be worn in a myriad of ways depending on what you need it to do (sun protection, stop sweat from dripping down your face, etc.).

Interestingly, some people I passed thought I was Muslim because I was using it to shield my whole face from the sun.