First things first - this 12oz bottle is a beast! After 6 months of daily use for both Japanese calligraphy and experimental ink washes, I've barely made a dent. The carbon black pigment density is unreal.

What surprised me most was how it performs on different surfaces. On rice paper, it gives that classic matte sumi-e look I crave, but when I mixed it with gum arabic for a fountain pen project on bristol board? Crisp, smudge-proof lines that held up under light watercolor washes. Though fair warning - one reviewer's right about the potent traditional sumi aroma (I personally find it nostalgic).

The bottle design deserves its own praise. That controlled pour spout saved me from at least three potential ink disasters when my cat decided to 'help' with artwork. For manga artists - the way it layers under screentones without reactivating is magic.

Is it truly waterproof? In my stress tests: light watercolor glazing over fully dried ink = no problem. Heavy scrubbing? Some pigment lift. For the price, I'd say it delivers 90% of premium waterproof inks at twice the volume.

Pro tip: Dilute with distilled water in a separate container to prevent bacteria growth in the main bottle. My current mix (1:3 ink to water) creates the most delicate cherry blossom branch gradients.