Not your grandfather's comic book inking techniques..

Mike Mignola

Francis Valejo

Jason Shawn Alexander

Frank Miller (Klaus Jansen inks I believe)

What do they all have in common, aside from being considered modern, unconventional, or even avant-garde artists working in the comics field? 

None of them use the standard comic book techniques of hatching or feathering. In the fields of superhero and horror comics of the last few decades, these techniques have been a mainstay - it was basically mandatory for aspiring artists to master them, which requires amazing control over line thickness and exactly where both ends of a group of fine lines falls. Especially in the case of feathering, with tapering ends on the lines (rat-tail strokes as I've learned to call them) - with feathering you can't just come back in and clean up the edges of your groups with white - you need all the lines to taper at the same rate and end on the same curve. It's pretty much what makes inking so difficult, and also what makes it possible to get good subtle shading. 

But all of these guys have foresworn it. Instead they mainly seem to rely on well-designed, strongly graphic areas of black and white to create chiaroscuro (patterns of light and shadow that reveal form, usually very strongly contrasting). And where they want some gradient in between, instead of fine, closely packed lines all in a neat row like little soldiers, they make marks of various kinds. Sometimes rather randomly, like splattering, sometimes very controlled. Sometimes those marks are lines, sometimes they're more like dots or dabs. And many of these artists don't use traditional dip pens and brushes either, but have opted for markers instead. 

Mignola, according to his website, uses Staedtler pigment sketch pens for lines and Higgins Black Magic ink for large areas. Alexander does seem to use dip pens and brushes for the most part. With some it's hard to tell, but I'd say Simonson uses markers for his lines - they look too unvarying for dip pens.

Some of them occasionally do use groups of parallel lines for shading, but it rarely resembles traditional feathering or hatching. It's often much rougher, with no real finesse for the exact shape made by the groups of lines, and they rarely taper on the ends like feathering. It tends to feel a bit clunky in comparison, raw and modern, sort of like alternative rock compared to carefully orchestrated progressive rock of the 70's. Done with a blunter instrument, and not ashamed of it.

I just saw a Mignola interview in which he said you can't just try to enter comics with thus kind of style - he and everyone else who do it began the usual way - Bill Sienkiewicz started as a Neal Adams clone for instance. Then once you've paid your dues and proven yourself you can relax and start to do your own thing. I believe this serves to ensure that you know how to draw well - I can see people wanting to just ignore traditional technique and jump straight into the modern look without developing the skills these guys have.