What black ink do you recommend for old Rotring Rapidograph (#1 and 2) pens? They are primarily for drawing on suitable coated paper. Ages ago, before the www had even been conceived, ignorance of finer points of ink was hard to overcome. So I used whatever was available, both for ink and for my paper, and it fortunately worked adequately. I am returning to drawing and want to load them with more care. This ought to open new vistas. I have been sketching some with my daily driver Pelikan with the gold EF nib and Pelikan blue black, re-acquainting myself with drawing rather than writing.