Watersoluble graphite pencil

I got a 2B and 6B watersoluble graphite pencil the other day. I didn't even know these existed. I really like them. You can't move the colour around the page much, and I was surprised just how much darker the 6B was. They look fairly similar when dry, and then when wet, the 6B leaps out of the page. I used my water brushpen that I use with watercolour pencils.

Bridge near Wanganui River, North Island, NZ