This post rounds out my review of the newest four inks to be commercially released by Blackstone Inks - a 4-pack of mixable "primary" colours.
Black is the least interesting of the lot - for the obvious reason that it's black. It doesn't have any "special" qualities such as waterproofness - it's designed to mix with the other inks in the range, rather than to serve as a stand-alone ink.
That said, this is a very "honest", well-performing ink. It's a "pure" black that washes out to produce a grey colour, and (depending on the pen) tends to dry as a "grey-black" rather than a straight black.
I wouldn't have bought this ink if it wasn't part of the package - I already have another 3 bottles of black, at least! - but it's actually pretty good in its own right. In a wet enough pen (my Pilot Metropolitan seems to qualify), and on a coated-surface paper like Rhodia, I managed to get an almost pure black patch of ink with "shiny" (not sheeny) finish.
Not bothering with the photo this time, just the scan: