i just bought a new hemp necklace today it's really rough i already put it in some water to try and soften it up but it still feels a little on the rough side.
arlia is right but if you want quicker results : I find that if you soak it in hot water, apply hair conditioner, and then soak it again in cold water, it tends to soften up (I use to make and sell them)... BUT - there are different types of hemp string (its usually not 100% hemp) so it's not garenteed to work.
After i made my choker, it was really stiff and rough, but then i went on a day-long float trip and it really helped. So now you got an excuse to have some fun in a river before the summers over!
i usually let it soak over night in luke warm water with a little bit of sea salt to soften it up. i use it on all my necklaces.
I kind of enjoy the picky feeling of new hemp...sometimes I wish it would last longer! Especially on thick necklaces, it feels rather nice to me.