I don't really understand it myself so I can't explain how it works,
what i can do is point you to several sources ive been studying myself for solid black ''methods''
The first that come to mind are pretty obvious: Mike Mignola (Hellboy), Frank Miller (Sin City) and Eduardo Risso (100 Bullets)
Then there's Sean Gordon Murphy like Angie said
Matteo Scalera
http://matteoscalera.deviantart.com/ has a more sketchy approach to hard blacks and might be what LeFred was talking about having texture in the blacks (sorry LeFred if that's not what you meant)
Then there's Becky Cloonan
http://beckycloonan.deviantart.com/ who somehow manages to make her hard blacks look soft, she doesn't emphasize the black as much as every one listed above, but she still has a lot of black in her works.
Finally, if your looking for hard blacks purely as shadows, Mahmud Asrar
http://mahmudasrar.deviantart.com/ is pretty good at that.
And if nothing else, trial and error always works. Try putting blacks at different places, see if it feels right, follow your gut.
I'm really passionate about solid blacks sorry