Delicate yet practical (Twsbi Blue-Black)

The notebook is Clairefontaine 90gsm. Text from Gödel, Escher, Bach by Douglas Hofstadter.
TWSBI Blue Black is a matte blue-black. It has an excellent flow and a slightly lubricated feeling. It is almost completely water resistant. It also works on cheaper paper without bleeding through too easily, even in a broad nib.
As part of TWSBI’s basic ink range, it is available in 70ml bottles, at a good price per ml, although the size means it is still an investment. I bought mine for £15.
When you open the weighty, chilly glass bottle of ink, you will notice the scent of iris1. The fresh ink is a vibrant dark blue, but it dries to its usual dusty colour. There is occasionally a slight inky smell while writing - if you have a sensitive nose, beware.

I am a fan of the bottle’s design. The frosted glass is a unique touch.
This ink is strongly water-resistant. Even if I run my writing under the tap, it only blushes with a hint of excess blue pigment. TWSBI do not label it an iron gall ink - they seem to be confident the formulation will not damage pens - but the colour darkening, and the water-resistance, are characteristic of iron gall. I wonder if the iris scent comes from some chemical added to make the iron gall component more ‘safe’.
I didn’t have trouble cleaning it out of my Pilots just by flushing, but I did find that I needed to pull out and wash the feed and section of my Lamy CP1. To be on the safe side, I’ll warn that this ink might be a little harder than normal to clean out2.
There is shading when writing, especially in a broader nib. It’s hard to capture exactly how it looks in a photo. Compared to a typical ink there is slightly more hue variation - from lighter grey-blue to darker blue-purple. Just enough to create the illusion of vibrancy and complexity while remaining unobtrusive.

Lamy CP1, B nib
This is a classy ink. Distinctive if you’re obsessed with colours and inks, blue-black to everyone else. The other properties such as water-resistance and performance on cheap paper make it an good option for everyday use. It may be in TWSBI’s basic ink lineup, but basic here means practical, versatile.

Pilot Prera, F nib
In use
At the moment, Twsbi Blue-Black is my favourite ink. There is something satisfying about the matte permanence of it. And I am not usually a fan of shading, but it is my favourite thing about this ink. I like to use it in my journal, filling up pages with the delicate colour that doesn’t look boring even next to bright accents.

Pilot gold F nib, alongside Diamine Aqua Lagoon and J. Herbin Ambre de Birmanie
Going by my current track record, 70ml of ink will last me about a decade. I say bring it on.

Lamy CP1 B nib, alongside Diamine Grey and an orange mix
-
Also known as the scent of boiling carrots and lipstick. I’ve never smelled either of those and only associate it with iris perfume. ↩︎
-
You may find a thread on FPN about how it dried up and jammed a pen shut. However, later in the thread, the poster shows a writing sample of it as a dark blue sheening ink. TWSBI Blue-Black doesn’t sheen! Either the bottle went bad or they’ve changed the formula since then. ↩︎