Noodler's Borealis Black Fountain Pen Ink Bottle, 87ml.
True, this Borealis Black is very black. Bulletproof Black seems much less saturated by comparison. Borealis flows smooth and wet with a bit of bleedthrough visible. The downside to the ink is that it is not "bulletproof," or fraud-resistant. It can be removed with bleach, some carpet cleaners, and laundry detergents.