OPUS 88 Demonstrator Fountain Pen - Mocha Mousse
A warm, coffee-toned pen with effortless writing comfort
The Opus 88 Demo Mocha Mousse is a full-sized fountain pen finished in a rich, coffee-inspired brown opaque acrylic. It provides a softer, more grounded aesthetic than the original clear demonstrators. Built around a high capacity eyedropper filling system with a shut-off valve, it is designed for long, uninterrupted writing.
What sets it apart
- High capacity eyedropper filling system for extended writing sessions
- Shut-off valve provides control and reduces risk of leakage during travel
- Warm mocha toned acrylic with a soft, coffee-inspired theme
- Large, ergonomic form designed for comfort during long writing
Feel in the hand
The Mocha Mousse feels calm, steady, and grounded. The warm brown tones create a sense of comfort and familiarity, similar to a well-made coffee on a quiet desk. It encourages slow, thoughtful writing while still offering the visual engagement of translucency in the grip section.
Who it’s for
- Writers who prefer warm, earthy colour palettes over brights
- Users who want high capacity pens for journaling or long writing sessions
- Fans of the original demonstrator model who still want an opaque version
- Those who enjoy coffee-toned, neutral desk setups
- Anyone who values comfort and ink capacity in a daily writer
Not for
- Users who prefer compact or pocket-sized pens
- Those who want cartridge or converter simplicity
- Writers seeking highly bold, high contrast finishes
Practical tips
- Open the shut-off valve slightly during writing to ensure consistent ink flow
- Close the valve when transporting to prevent leakage
- Fill slowly to avoid air pockets in the barrel
FAQs
Is the Demo Mocha Mousse transparent?
Just the grip section for a glimpse of the ink flow and the end cap.
How does the shut-off valve work?
It controls ink flow from the barrel to the nib. Open it slightly while writing and close it when not in use or during transport.
Do I need to add silicone grease on the grip threads to prevent leaks?
No, the design includes a thick o-ring already.
Is it suitable for beginners?
Yes, though like all eyedropper pens, it requires a little more care than cartridge systems.
Can it be used with document and shimmer inks?
Yes, but regular cleaning is recommended to maintain consistent flow.
How large is the pen?
It is an oversized fountain pen designed for comfort and long writing sessions.
What other nibs is it compatible with?
Other size #12 JoWo nib units and also the nib unit from the Pilot Parallel art pen.
What’s included
- Opus 88 Demo Mocha Mousse Fountain Pen
- Eyedropper
- Spare small o-ring for back of nib unit
- Instruction leaflet
- Free nib tuning from LarryPOST
Ink pairing suggestions
- Sepia inks for a cohesive coffee toned palette
- Chocolate browns for a deep, rich monochrome look
- Burnt sienna inks for warm, earthy continuity
- Deep navy for a classic, professional contrast
Build your practice
- Pilot Iroshizuku 50mL ink for volume
- Herbin inks, lots of browns
- Opus 88 replacement #12 nib unit
Specifications
- Brand: Opus 88
- Brand series: Demo
- Launch: 2018
- Origin: Taiwan
- Nib: Jowo #6, black stainless steel
- Nib sizes: EF, F, M, B, 1.5mm stub
- Filling system: Eye dropper
- Material: Acrylic, black clip
- Trim: Stainless steel
- Weight: approx. 27g (capped)
- Length: approx. 147mm (capped)
- Diametre: approx. 17mm
- Comparable size: Twsbi Diamond 580
A high capacity fountain pen with a warm, coffee toned aesthetic.
