What is the best ink for work and documents?

A well-behaved blue-black or black with water resistance: professional on the page, fast-drying on office copy paper, and safe if a coffee ring or a rainstorm finds your notes. Pigment blacks (Platinum Carbon) and "bulletproof" formulas (Noodler’s Black) are the archival tier.

Avoid heavy sheeners and shimmers at work — they dry slowly on cheap paper and photocopy oddly. Save the fireworks for correspondence.