The blue black. Sometimes I like to try all different brands of blue black inks just to see if they are all “water proved”. Most of them are, so far only Waterman’s Blue Black isn’t. Sheaffer Blue Black is more toward the grayish blue side which similar to some of the KWZ IG Blues.
Slightly longer drying time amount all the blue blacks, probably due to the B nib (later on I fount out it might be an OB instead of a B). Good saturation with low shading. It does show water resistant to certain level but isn’t as dry as some other Blue Blacks. It doesn’t bleed or feather on iPaper UCCU or PaperOne 70gm.
I would say it’s an interesting color but probably won’t meet the standard of the blue/black code for office use. Kinda sad.
CP value: 89/100, it’s cheap but just not dark enough.