Matsubokkuri - Storm Glass+ Obsidian | Glass Pen

Matsubokkuri Storm Glass+ Obsidian Glass Pen

Obsidian is volcanic glass — stone born from the same violent transformation of heat and material that shapes every Matsubokkuri pen at the torch. It's a fitting pairing. Inside this pen's hollow shaft, a shard of natural obsidian shares the space with a clear storm glass liquid, a 19th-century sailor's weather instrument repurposed here as ornament: as temperature and pressure shift, the liquid drifts between perfectly clear and dense with feather-shaped crystals, sometimes overnight, sometimes over the course of an afternoon at your desk. Tilt the pen and the obsidian tumbles past the crystals — on a still, clear day, the stone alone holds the eye.

Why Obsidian

Unlike the paler stones in the Storm Glass+ line — rose quartz, moonstone, citrine — obsidian is opaque and near-black, so it reads less as a gem and more as a fragment caught mid-formation inside the glass. It gives this particular pen a darker, more mineral presence on the desk than its Storm Glass+ siblings, and pairs well with darker inks: sumi-adjacent blacks, deep blue-blacks, or Matsubokkuri's own dip-and-write use with shimmer inks that catch light against the stone.

The Pen Itself

Every Storm Glass+ pen is shaped freehand over an oxygen torch by Kiyoshi Matsumura at Glass Studio Matsubokkuri in Suginami, Tokyo — no two are identical, and the obsidian's exact shape and position inside the shaft will vary from the one pictured. The hollow construction keeps the pen light for its size, and a collar built into the base of the nib stops it from rolling when set down mid-sentence.

Specifications

• Total length: approx. 175mm
• Shaft diameter: approx. 12mm
• Weight: approx. 21g
• Contents (non-toxic): water, ethanol, natural camphor, ammonium chloride, potassium nitrate, natural obsidian
• Nib width: Fine (F), Medium (M), or Broad (B)
• Handmade in Japan

Using and Caring for a Storm Glass Pen

Dip the nib fully before writing — the spiral-cut grooves hold enough ink for several lines per dip. Rinse under lukewarm water after use; avoid hot water or sudden temperature swings, which can stress the glass and, over time, affect how readily the storm glass crystallizes. Nib repair is available through Matsubokkuri for the life of the pen.

Frequently Asked Questions

Does the storm glass crystallize on a schedule?
No — it responds to the specific temperature and humidity of wherever the pen is kept, so the pattern is different pen to pen and day to day. Some owners find it clears in warm rooms and crystallizes overnight in cooler ones.

Is the obsidian real stone?
Yes, a genuine piece of natural obsidian is sealed inside during glassblowing, which is why size, shape, and placement vary slightly between individual pens.

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