Sketching with water soluble pencil

Some months ago I watched a video in which David Bellamy charged about Welsh mountains and the Pembroke coast. His enthusiasm and ability to withstand the cold are entertaining and enviable respectively. On one location he sketched with a water soluble pencil, something I'd not used before, so decided to investigate. I bought a couple - 4B and 6B and teamed them with a Pentel water brush, which precludes the need for a separate pot of water. From the first stroke I was hooked and now use the technique as my preferred sketching method, it's quick and easy, producing both hard line and soft wash with ease, giving the drawing plenty of the wonderfully accidental atmosphere. I made a short video showing a memory sketch of the London skyline.

Below are a few examples of my water soluble pencil sketches.