Questiom about semen consistency when in contact with water

Hi all, I'll have to be pretty blunt with this post.

My partner came on my face in the shower yesterday and it dripped onto my chest and legs.

I immediately tried rinsing it off (seemed like an okay thing to do) but it immediately got harder and sticky, I had to sort of rub my face really hard so it would roll up and come off.

It also got onto my legs, as I mentioned, and it hardened on my leg hairs and for some reason it really hurt to wear pants. It felt as if the hairs were being tugged at.

1. Why does this happen? A chemical reaction? Was it because of the hot water temp? Is semen hydrophobic?

2. How can I efficiently clean off semen in the future?