If you're looking for a rich, dark black ink for your fountain pen, look no further than the Private Reserve formula of Velvet Black. You're not going to have the fraud-proofing qualities of a Noodler's Bulletproof black, but you will get a darker, more saturated black that flows well from the nib to the fibers of the paper.
I had a chance to try out the new Visconti Homo Sapiens Lava fountain pen with Velvet Black and had very satisfying results. The flow is excellent. No feathering, but there is a significant amount of bleed-through on the opposite side of the page of my Levenger Circa paper. Forget about using on a Moleskine. Pretty slow drying time at between 2 to 3 seconds.
I would recommend using Velvet Black with a fine or extra-fine nib on a heavier-than-normal paper quality. If you have your own experience with this Private Reserve color, please share and let me know what pen and paper combination you use with the ink. What works best for you?