tl;dr: as expected, this is a fabulous looking and performing ink. It’s wet, it exhibits moderate shading, has a pretty purple sheen in saturated areas, and is smooth.
I recently acquired a bottle of Pilot Iroshuzuku tsuki-yo ink (Amazon)(Goulet Pens) for a company off-site and thought I’d share my thoughts here.
At EllisLab, we work entirely remotely and only meet in person once a year, sometimes less frequently. So when we met in Nashville, TN last week for some planning, I thought I would spread my fountain pen addiction to my coworkers. It’s only fair since it was a coworker who put me on to fountain pens in the first place. I got Pilot Metropolitans for everyone, and wanted an ink that was similar to the company’s branding colors. Iroshuzuku tsuki-yo was about as close as one could get.
As you can see, it’s not particularly fast drying, but for a wet ink that’s not bad on Tomoe River paper. The drip test shows that water/coffee droplets will definitely impact your writing, though not completely erasing it.
The splatter is more impressive in person, but it really demonstrates how beautiful this ink is, and at various angles the sheen looks like metallic purple. I also have fun with my syringes.
The swab passes show the sheen on the edges as well, where the ink definitely pooled from my drippy q-tips.
A more serious water resistance test is shown here. I waited between 5–10 minutes for the ink to dry and then dipped the paper in a basin of water and held it there for a ten count. I wish I had the presence of mind to video it, as it was rather pretty to watch the ink form dozens of ribbons in the water as it was pulled from the page. This is not an ink for archival purposes or documents where true waterproofing is absolutely necessary, though you can see that even in this extreme example, the ink is not fully erased and is still quite legible.
I still like the color and properties of kon-peki slightly better, but I will have no qualms about keeping this ink in rotation in one of my pens at all times.