Ah ah, an artirt never reveals his sec- wait. No that would be magicians. Heh. No okay so for my construction lines and detailing i use a Faber-Castiel (supernatural reference) HB pencil which i need to be so freaking careful with lest the lines darken irrerasably (word creation is fun!) and sharpen up to twice for consirtency. I know i erase all the pencil work but it stil helps for inking. Speaking of inking - which i strongly suspect was the topic of the question - i use an Artline200 0.4 Fineliner which is great! They seldom bleed but you need to have paper of a good thickness otherwise it is clearly visible on the other side. Utter rubbish for that thin, lined writing paper. They also require slow to moderate usage speed for long lines - say with a ruler - or work becomes inconsistent. But going over detailing lines is never something one rushes...im sorry for the tl-dr, i just assumed anyone who reads this will recognise the awesomeness of the inking pen and go buy one or want to know how to use one...um...