While not the most exciting topic, I get a lot of questions about the inks I use at work. I generally take the position that any ink is “work appropriate” as long as you have the confidence to pull it off (hello, Yama-Budo), but understandably, some work environments—and the paper they stock in the supply cabinet—are more tolerant of our craziness than others.
If I know that I will not have access to a stock of decent paper, and I’m in a situation where I don’t want to rock the boat color-wise, my go-to ink option is either Sailor Kiwa-Guro nano-black (a pigmented writing ink), or one of the various bottles of basic royal blue inks that I have lying around. Some might consider the Kiwa-Guro too pricey for a bottle of black ink, but if feathering and bleeding on cheap paper really bothers you, this is by far the best option. Noodler’s X-feather also probably won’t bleed or feather on cheapo paper, but from what I’ve heard, it takes forever to dry so I don’t consider this a viable option for work if you need to take multiple pages of notes in a short time-frame (i.e., you're flipping pages of your notebook or legal pad before they dry). Noodler’s inks and pigmented inks like Kiwa-Guro also require more maintenance, and you should pay attention to how often you flush out your pens or else you may get a clog.
I have four options for basic blue inks, which is ridiculous, but hey, this is my “job". They are, in no particular order of preference:
Waterman Serenity Blue (formerly “Florida Blue”). This ink is more or less the gold standard for “safe” blue inks, and has an almost cult-like following among vintage pen collectors because apparently no one has ever seen this ink stain a pen. The first bottled fountain pen ink that I ever purchased, Waterman blue holds a special place in my stockpile and I use it regularly. It works well on most papers, even in a wet stub nib.
Rohrer & Klingner Koenigsblau: I would call Koenigsblau a slightly brighter version of Waterman blue. It’s equally well-behaved on most papers, but probably a touch more likely to feather and bleed. Rohrer & Klingner inks work well in most of the pens in which I’ve used them, and are generally regarded as safe. I’m also liking Leipziger Schwartz (a greenish-black).
Writing sample of Koenigsblau and Waterman Serenity/Florida Blue. Note that each of these inks appears fairly washed-out when dry, at least on less absorbent paper like Clairefontaine or these Nock Co. dot-dash cards.
Iroshizuku Asa-Gao: Perhaps the ink I’ve recently enjoyed the most. The Asa-Gao dries with a dark sapphire-like tinge to it, not quite as nice as Bung-box Sapphire but close. I have only a 15ml “mini-Iroshizuku” bottle and will be picking up a full bottle as soon as that one runs out. Compare how bright the Asa-Gao remains when it dries, as opposed to the much more washed out Waterman and R&K.
Probably the most accurate comparison. The Asa-Gao is the brightest, the Koenigsblau second, and the Waterman third. The Koenigsblau shows better in this picture because I used a pen with a wetter nib.
Other blue inks that I’ll throw out there as good everyday options include: Aurora Blue (slightly more purple-violet); Sailor Nioi-Sumire (same); Bung-box Sapphire; and Sailor Souten (a sky blue). Your mileage may vary in terms of what's "acceptable" in your place of work (or you may just not care), but using one of these blues probably won't cause others to look twice (unless it's to ask where you bought the bottle).