If you crave the bold, sharp contrast of a pitch-black ink, Noodler's Heart of Darkness and X-Feather are about as black as black gets. The two are equally dark, and which one you should get depends on whether you prefer faster drying times or better performance on absorbent paper. Heart of Darkness dries very quickly, but it can feather and bleed through on absorbent and lower-quality papers. X-Feather, on the other hand, performs well on even the most absorbent papers, but it is also one of the slowest-drying inks we’ve seen, especially on smooth, high-quality papers.

Both of these inks are part of Noodler’s “Bulletproof” line. They use a special cellulose-reactive formula that binds permanently with wood pulp and cotton fibers. This means that are slower-drying and less permanent on very smooth papers like Rhodia and Clairefontaine. They also don’t work well on non-cellulose-based papers like stone paper.