Ink Review - Pilot Iroshizuku kosumosu 

Today I’m reviewing Pilot Iroshizuku kosumosu ink.

Kosumosu is a light pink ink that translates to Cosmos from Japanese. It tends to lean slightly blue like “baby” pink inks, but it’s still very legible compared with some lighter pink inks. It’s exactly what you might think of when you look for a pink ink.

Kosumosu is a well-behaved ink that flowed very nicely through my pens and felt smooth to write with even though I noticed a small amount of feedback. I didn’t notice any skips or hard starts when I put the uncapped pen down to do swab tests, dry times and water resistance. I also didn’t see any feathering on the papers I wrote on. It has nice shading but I didn’t see any sheen with normal writing.

It dried very quickly in 10 seconds on the Clairefontaine Triomphe paper and didn’t smear after it was dry.

Available in attractive Pilot Iroshizuku 50ml glass bottles from The Writing Desk

  • Flow Rate: Good.
  • Lubrication: Smooth.
  • Nib Dry-out: Not noticed.
  • Start-up: Immediate.
  • Saturation: Not saturated
  • Shading Potential: Nice shading seen.
  • Show-Through: None seen on Clairefontaine Triomphe.
  • Spread / Feathering / Woolly Line: Not seen
  • Nib Creep / “Crud”: Not seen, even after a week in the pen.
  • Staining (pen): Not seen after several days - easy clean-up.
  • Staining (hands): It took two washes before my hands were clean.
  • Clogging: Not seen.
  • Water resistance: Not sold as waterproof but it is water resistant.

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