On Youtube I found this video how he sketched a Chicago scene during last year symposium, some overhead metro track.
So I tried out the same scene, and used a few of his tricks (as far as I can tell from the video of course). That is, putting the ink in a small jar, with some bandage gauze. And cutting the bamboo stick fresh.
To be honest, I tried these things before with mixed results, the ink never came out as grey as I wanted. So today I tried putting the bamboo in water first, so the wood is soaked. And voilà, at last I got the result I was looking for.
Not quite what Kiah Kiean can do with this technique, but a promising start.