Synthetic coolMax (or similar non branded) is the perfect base layer. It can be washed/rinsed anywhere, can be put on wet and wil dry in place in 10 min. Flows sweat away from skin but holds it where it will evaporative cooling you. Very handy to have and perfect base layer for long days on the road. I also use runners type synthetic T shirts as they perform better than cotton for the same reason. Avoid cotton as a base layer.