Review: Kosumosu Iroshizuku ink by Pilot

Kosumosu, Nanami paper Crossfield journal and pilot custom heritage 912 fountain pen

I’ve been seeing pilot inks around a lot lately. But as a diehard Noodler’s ink fan, I’ve hesitated to look beyond that particular brand, because there are so many of the Noodler’s inks I still want to try and haven’t yet. Pilot ink’s are also what I would consider on the expensive side, at around $20 for a 50ML bottle.

The bottle itself however is GORGEOUS. It’s very aesthetically pleasing to look at.


When I choose an ink, I choose one from a color I don’t already have. Red, yellow, and pink have been on my wishlist for some time now. So when I saw Kosumosu and saw the ink samples on the Goulet pens website, I knew I’d found an ink that I was going to purchase.


Pink is not a color that I normally like, or go for. But I like having a full spectrum of ink colors at my disposal, so I knew that I was going to purchase a pink ink, even if it isn’t really a color I normally gravitate to. Just like I know I will one day purchase a yellow ink (Still on the search for one of those).

Kosumosu on Original Crown Mill Laid Paper

But knowing that I’m not drawn to pink as a color, meant that I really had to find a pink ink that I loved. I don’t just go around buying ink because I can, I have to love it. I need to want to use it. That means pink is an ink that I research first, because I don’t want to regret my purchase after the fact.

Regretting a purchase really, really sucks.


I DON’T regret purchasing Kosumosu.

It’s really one of the loveliest pink inks I’ve seen in quite some time. I would consider it soft and gentle, and a tiny bit closer to pastel, than to vibrant pink. Maybe closest to Salmon pink.

It dries quickly, but I’ve only used it with my Pilot Custom Heritage 912 pen with FA nib, because I’ve found that I love that combination best. And now that I’ve found a combination that I love, I seldom change it. Or if I do change it, it will be when I run out of the ink. Which isn’t going to happen for the foreseeable future.


As I said, the ink dries quickly, it doesn’t bleed or feather on Clairfontaine paper, or on Crown Mill Laid Paper. Nor does it bleed or feather on Rhodia paper, or Leuchtturm 1917 paper. I think this ink works perfectly with smooth fountain pen paper best.

I haven’t tried it on regular paper, and I didn’t really see the point, since I rarely use my fountain pens on regular paper. And if I did, I would only use fine or extra fine nibs, in order to limit the feathering and the bleeding that would be bound to happen with any ink.


Kosumosu is an ink that I’ve come to look forward to using with my flex nib. And for me, that’s saying a lot.

In fact, I feel as if my Pilot Custom Heritage pen works BETTER with this particular ink, than it did with some of the Noodler’s inks I’ve used in the past. Maybe it’s because Kosumosu has a slightly thinner consistency, I don’t really know. But whatever it is, it works, and I love it!


Looking forward to finding some more Pilot inks to purchase. Like maybe a gray next time.

Thank you for reading!




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