tgreco
Sr Member
Sounds good on the pencil. I had forgotten over the years about the varying lead hardness (been a while since I've taken a fill-in-the-bubble; No. 2 pencil test!). On the model, it looks strongly as if they used both lead, and ink - the jet black lines were likely a very fine-tipped marker.
could also be that they used variable lead hardnesses
some soft leads are pitch black, and the harder ones look a bit more silvery