I've got enough black inks. Heart of darkness (bulletproof), black quink(old faithful), X feather, and a bunch of greys to round it out. I always wanted to try dark matter, mostly out of novelty. But I quickly realized that it's just a great black ink.I'm not the biggest fan of blacks, but the novelty of this made me buy it, and I'm glad I did.The history of this ink is that Nathan Tardiff (the man behind Noodlers) got a bottle of ink from someone, that was pretty certainly traced back to the ink used at Los Alamos, New Mexico between 1942 and 1945 (during the manhattan project, the ink used by the scientists working on the nuclear bomb.) He replicated it exactly, from the color to its exact waterproofness and flow characteristics. So here it is, the same ink used by the minds behind the atom bomb. The bottle is inscribed with "Now I am become death, the destroyer of worlds" - a quote from J. R. Oppenheimer, director of Los Alamos during the development of the bomb.With a pilot metro fine on the absolute WORST paper I've ever seen (some see-through printer paper I got from the grocery store that's basically kleenex) it feathers noticeably, but not terrible, and that paper is worse than anything you'd be likely to find, even out of a copier at work.On regular paper, it writes just fine, like any black should. A little more feathering than quink black (which itself is only a little worse than X feather) but better than heart of darkness. Dry times on most papers is great, under 5 seconds for the pilot on rhodia and instant on anything more absorbentNo smudging.The color is really, truly black, with none of the colored undertones of other blacks. When you rinse this ink it just goes black to grey. basically zero shading. Very professional.There's some decent water resistance, not quite as tough as heart of darkness or any real bulletproof ink, but it's actually quite reasonable. I used it all week in the field writing patient charts on kinda bad paper and getting rained on without issue.I think the real standout feature is the flow. This stuff is slippery and WET. It flows better than quink, which is an outstanding quality ink from a flow standpoint. My metro does have some proclivity for dryish writing, and this stuff turns it into a very wet writer. Same goes for my fine platinum balance. If you have a dry writing pen and just can't seem to like it, try dark matter, this stuff flows better than any other ink in my collection of 30+ inks.I'm not a huge fan of blacks or blues (I much prefer dark reds, browns and green for my professional work) but like heart of darkness in a noodlers charlie, I have a really strange love for this ink. I REALLY like wet writing inks, and this is the wettest black I've ever written with (Even though it doesn't matter as a black, I like the slight glint of the sun on wet ink as I write) add that to the history (this is a copy of the black ink used during the Manhatten project) and I am really happy I bought it.